Guidelines for Scientific Writing
Sharing the results of scientific activity with other scientists is an integral part of the scientific process. You can perform a brilliant experiment, yet if you cannot clearly explain your results and convince the reader of their importance, the experiment will go unnoticed. In a recent survey of employers of scientists, a lack of communication skills (in particular written communication skills) was the greatest deficiency found in their employees. Seventy percent of employers said that their employees were poor writers.
A scientific paper must fulfill two objectives. First, it must accurately describe the procedures that were followed and the results that were obtained. Second, it must place these results in perspective by relating them to the existing state of knowledge and by interpreting their significance for future study.
Scientific papers are written in a standard format with the following sections; abstract, introduction, materials and methods, results, and discussion. References and figures are usually included after the discussion. Each section contains specific information about the research being described. In the following document, a description of the information found in each section will be outlined, along with some common mistakes made by students. The best way to get a feel for how a scientific paper is organized is by looking at articles in primary journals. There are many such journals in the library.
All formal papers should be typed, double-spaced and checked for spelling and grammatical errors.
In the following pages specific details of what goes into each section of the paper will be described. In general there are six things that all scientific papers should do:
(1) Trace the scientific origins of the research problem.
(2) Summarize the state of knowledge on the subject.
(3) State the critical hypothesis being tested in the research project.
(4) Interpret the results of the study in relation to these hypotheses and to the general state of knowledge.
(5) Identify the scientific questions and procedural weaknesses that need to be addressed in the future.
(6) Be concise.
Title
Each piece of scientific work should include a concise but descriptive title. While it is important to be short and concise (essentially one sentence) you do not want to be vague or incorrect. The title should reflect exactly what you did in your study. This is also your first shot at grabbing the reader’s attention.
Example 1 - “Recombinant Human Antithrombin III” This doesn’t tell the reader much about the paper. Instead “Expression of Biologically Active Human Antithrombin III by Recombinant Baculovirus in Spodoptera frugiperda Cells” tells the reader what is in the paper.
Example 2 – “On the discovery of a useful new laboratory research method for isolating and purifying the lactose-degrading enzyme b-galactosidase from the economically important, yogurt-producing bacterial species Lactobacillus bulgaricus”. This needs streamlining!
Example 3 – “Studies on a snake”, again too brief. What snake, where, what kinds of studies? Instead “The Thermal Ecology of a Population of Timber Rattlesnakes (Crotalus horridus) on Brady’s Bluff, Wisconsin”.
Abstract
An abstract summarizes your paper or presentation in one concise paragraph (usually less than 250 words). The abstract should state the object of the study, methods employed, summarized results and primary conclusions. It is usually easiest to write the abstract after completing the other sections of the paper. A sample of a well-written abstract is included below.
Mass mortality and extinction in a high-elevation population of Rana mucosa.
David F. Bradford. Environmental Science and Engineering Program, School of Public Health, University of California, Los Angeles, California 90024 USA.
ABSTRACT: Rana mucosa is one of several high-elevation amphibians that have recently disappeared from seemingly pristine sites. The present study documents an event of mass mortality among larval and metamorphosed R. mucosa in a lake in Kings Canyon National Park, California, and the ultimate extinction of the population. In 1979 metamorphosed individuals declined from ca. 800 individuals in early summer to nearly zero in late summer. During this time many carcasses were collected, individuals showed symptoms of red-leg disease, and blood from an affected individual contained the bacterial pathogen characteristic of this disease, Aeromonas hydrophila. Also during the summer of 1979, nearly all of the approximately 1100 tadpoles began metamorphosis, but all metamorphosing individuals were consumed by Brewer's blackbirds (Euphagus cyanocephalus). This population of R. mucosa continued to exist until at least 1983, but was extinct by 1989. Recolonization of the site will probably never occur because streams connecting to extant populations of R. mucosa now contain introduced fishes.
Checklist for the Title and Abstract
q Title is specific to project yet concise
q Abstract introduces topic
q Abstract mentions techniques used without going into experimental detail
q Abstract mentions most important results
q Abstract summarizes results
Introduction and References
The principal job of an introduction is to guide the reader from the broad area of your discipline to the particular topic you will be discussing. From a larger perspective on the problem, the introduction typically proceeds through several transitional sentences, leading the reader logically to the specific question you hope to answer with your experiment or topic you intend to discuss in your research paper.
An introduction also gives the reader the necessary background to understand why you are performing an experiment or writing the paper. In the introduction you should summarize the work done by other researchers in this area. For a paper in a typical class, most teachers would expect at least 3-5 relevant citations to appear in the introduction (see references). Remember, you should be careful to restrict background material to that which is directly pertinent to the problem at hand. In other words, you should always be able to justify why you included the material in the introduction to your paper.
In scientific papers, the most common type of reference comes from the primary literature, that is, from peer-reviewed scientific journals that summarize the results of original research. As a student, you are probably most familiar with information presented in text books, popular magazines, library reference materials or internet sources. With few exceptions, such sources are not normally used in scientific papers, and when they are, they are used sparingly and only as an adjunct to the primary literature. As such, in any writing assignments you are given you will most likely be required to include a minimal number of relevant references from the primary literature. Remember, popular magazines such as Natural History, National Geographic, Discover Magazine, Time, Newsweek, etc. are not considered primary literature!
In summary, the introduction section of a scientific paper should explain exactly what the objectives of the study are and why it is a worthwhile effort. To be most effective, the introduction should address the following questions:
(1) Why did the author undertake this study?
The best initial statement is often a description of an observation in nature, or a conclusion drawn from a survey of the literature, that stimulated the interest of the author.
(2) What is the existing state of knowledge of this topic?
The author should synthesize information from the literature into an account that traces the development of the problem and summarizes its current state. In particular, gaps or inadequacies of current knowledge should be identified.
(3) What is the author going to do?
He or she must indicate specific objectives or hypotheses that will be tested. These should be clearly spelled out and in the case of hypotheses, should be statements that are capable of being either supported or refuted by the planned work.
Finally, a common mistake in writing an introduction is to go into too much detail on what you did in your experiment, adding information that belongs in the materials and methods section or in the results section. Remember, the introduction is designed to explain the background that led you to perform an experiment or choose a topic for detailed discussion; it is not a summary of what you actually found or did!
The following is an example of an Introduction to a scientific paper:
Although the water economies of a number of species of amphibians have been studied, the majority of these investigations have been interspecific in nature (Smith et al., 1998). Such studies have often sought to elucidate adaptive differences among species (Schmid, 1965; Ralin and Rogers, 1972; Gillis, 1979). Although developmental stages of amphibians often occupy different habitats, corresponding changes in ecophysiological parameters have been relatively unstudied.
The red-spotted newt (Notophthalmus viridescens) has a more complex life cycle than many amphibians. Following a brief larval development, these organisms metamorphose and become terrestrial salamanders, the red-efts. After spending up to seven years in this habitat, these subadults go through a second metamorphosis to become aquatic adults (newts) that spend the remainder of their lives in water (Conant, 1975).
In view of the difference in habitats occupied by these two stages it was hypothesized that newts and salamanders should differ in terms of their water economy. Specifically, terrestrial efts should have lower rates of evaporative water loss and be more tolerant to dehydration than aquatic newts.
Literature Cited
When writing a research paper, it is essential that you acknowledge any works or ideas of others that have influenced your experiment, conclusions, or interpretation of the data. This is done by including a citation in the text and a reference at the end of the paper in the Literature Cited section that corresponds to that citation. The citation can be either a number or the author and year of publication, depending on requirements of the journal or your instructor. Whichever you use, remember to be consistent throughout the paper!
If you choose to use numbers as citations, the references appear in the back of the paper in the order that the citations appear in the text. For example, here again is the Introduction section using numbers as citations followed by the Literature Cited section for this portion of the paper:
Although, the water economies of a number of species of amphibians have been studied, the majority of these investigations have been interspecific in nature (1). Such studies have often sought to elucidate adaptive differences among species (2,3,4). Although developmental stages of amphibians often occupy different habitats, corresponding changes in ecophysiological parameters have been relatively unstudied.
The red-spotted newt (Notophthalmus viridescens) has a more complex life cycle than many amphibians. Following a brief larval development, these organisms metamorphose and become terrestrial salamanders, the red-efts. After spending up to seven years in this habitat, these subadults go through a second metamorphosis to become aquatic adults (newts) that spend the remainder of their lives in water (5).
Literature Cited
(1) Smith, J.W., D. Pettus and D.W. Hoppe. 1998. One hundred years of amphibian water economy studies: what have we learned? American Zoologist 66:124-198.
(2) Schmid, W.D. 1965. Some aspects of the water economies of nine species of amphibians. Ecology 46:261-269.
(3) Ralin, D.B. and J.S. Rogers. 1972. Aspects of tolerance to desiccation in Acris crepitans and Pseudacris streckeri. Copeia 1972:519-525.
(4) Gillis, R. 1979. Adaptive differences in the water economies of two species of leopard frogs from eastern Colorado. Journal of Herpetology 13:445-450.
(5) Conant, R. 1975. A field guide to reptiles and amphibians of eastern and central North America. Houghton Mifflin Co., Boston.
If you choose to use author and date as citations, the references appear in the back of the paper in alphabetical order. If there are more than two authors use the first author and et al. (Latin for “and others”) in the citation. For an example, see the introduction above. The Literature Cited section for this portion of the paper would appear as follows:
Conant, R. 1975. A field guide to reptiles and amphibians of eastern and central North America. Houghton Mifflin Co., Boston.
Gillis, R. 1979. Adaptive differences in the water economies of two species of leopard frogs from eastern Colorado. Journal of Herpetology 13:445-450.
Ralin, D.B. and J.S. Rogers. 1972. Aspects of tolerance to desiccation in Acris crepitans and Pseudacris streckeri. Copeia 1972:519-525.
Schmid, W.D. 1965. Some aspects of the water economies of nine species of amphibians. Ecology 46:261-269.
Smith, J.W., D. Pettus and D.W. Hoppe. 1998. One hundred years of amphibian water economy studies: what have we learned? American Zoologist 66:124-198.
For some other examples of how to incorporate references, see the following:
"Jones (1985) found that these lizards..."
"Since fence lizards are not found in Wisconsin (Ballinger and Lynch 1992),it is reasonable to hypothesize that..."
"Fence lizards appear to feed almost exclusively on insects and other small arthropods (Jones et al. 1965)."
Remember, the Literature Cited section should contain only items specifically referred to in the text and that all citations contain the complete reference in this section.
Although each journal may use a slightly different style for preparing citations, all provide sufficient information for the reader to find the literature cited in the library. That is, they usually include the last name(s) of the author(s), their initials, year of publication, title of the article, name of the journal or book (sometimes in italics and sometimes not), volume of the journal and pages of the article.
You will also note that most journals use standardized abbreviations for the titles of the scientific journals cited (except if they contain only one word - i.e. Science, Evolution, Oecologia, etc.). The journal Ecology, however, includes the full title name for each reference, which may be especially helpful to students not familiar with some of these scientific publications. For that reason in this course you should use the full title for each reference as it appears in this journal.
Observe the way in which the following types of references are cited in the journal Ecology:
Journal Article
Gillis, R. 1979. Adaptive differences in the water economies of two species of leopard frogs from eastern Colorado. Journal of Herpetology 13:445-450.
Jones, B.A., and N. Sikand. 1985. Variation in acid tolerance of Connecticut wood frogs: genetic and maternal effects. Canadian Journal of Zoology 63:1647‑1651.
Smith, J.W., D. Pettus, and D.W. Hoppe. 1998. One hundred years of amphibian water economy studies: what have we learned? American Zoologist 66:124-198.
Article in an Edited Volume
Pianka, E.R. 1975. Niche relations of desert lizards. Pages 292‑314 in M. Cody and J. Diamond, editors. Ecology and evolution of communities. Belknap Press, Cambridge, Massachusetts, USA.
Book
Conant, R. 1975. A field guide to reptiles and amphibians of eastern and central North America. Houghton Mifflin Co., Boston.
Smith, R.L. 1990. Ecology and field biology. Harper and Row Publishers, New York, New York, USA.
Internet References
In the text either use a number citation (1), or the author year (Smith, 1997). If there is no obvious author for the web site then use the company or institution instead (Perkin Elmer Inc., 1997). In the reference section give the entire URL as in the following example:
Perkin Elmer Inc., 1997. www2.perkin-elmer.com:80/pc/770024/770024.html
Quotations
Do not use extensive quotations. The only reasons for using the exact words of another author are (1) because it is this exact wording that is the focus of the discussion, or (2) because the wording carries the intended meaning in so striking a fashion that it cannot be easily paraphrased.
REMEMBER, you must always acknowledge the source of any ideas, facts, figures, etc. taken from others in the body of your paper. Also, using the exact words of another author without enclosing them in quotation marks is plagiarism, which is a violation of copyright laws as well as of University Policy - Don't even think about doing it!!!
Checklist for Literature Cited
q Required number of references in each category
q Each reference is relevant to the topic
q Correct citation style (e.g. author and year)
q Correct style for listing references (e.g. the journal Ecology)
q All references cited included in the Literature Cited section
q Only references actually cited included in the Literature Cited section
q Authorship of all ideas, facts, etc. properly acknowledged
q Quotations avoided
Writing Scientific Names
The cornerstone of the Binomial System of Nomenclature proposed by the Swedish botanist Carl Linnaeus in 1756 is the species, which consists of two Latin words. The first word (always capitalized) is the genus while the second word (not capitalized) is the species epithet. Although usually an adjective that agrees in number and gender with the genus it modifies, the species epithet may honor a biologist that discovered the species or did extensive work in the area. For example, Bufo viridis is the green toad (where viridis is the Latin word for “green” ). Rana blairi, on the other hand, is a frog named in honor of the famous herpetologist W.F. Blair.
A further important point is that since scientific names use a foreign language (Latin), they must appear in italics (or be underlined when writing them). To fail to italicize or underline is not only a grammatical error, it introduces a problem for the reader, since the one of the reasons for developing a system of scientific nomenclature was so that scientists from all around the world could recognize organism names without ambiguity. Note, however, that all other taxa – Domain, Phylum, Class, Order, Family, etc. are not italicized or underlined (although they must be capitalized as proper names). Although they may seem easier to use, common names vary from one place and language to another, which reduces their utility in scientific writing. For example, within the United States alone mountain lions have also called panthers, pumas, catamounts and painters, but to scientists all over the world, there is only one animal with the binomial Felis concolor!
Another important point is that the genus name can stand alone since different species within a genus often share very similar characteristics. For example, there are four species of the parasite Plasmodium that cause malaria in humans. The species epithet, on the other hand, can never be used alone, and it is meaningless without connection to a genus because there are often several genera that have the same species term. Consider Tilia americana, Fraxinus americana and Ulmus americana. All are scientific names, all have the same specific epithet, but all are classified in different genera. Although it is common to hear some people refer to the genus and species of an organism, this is redundant since the species name includes the genus as well as the specific epithet. Remember: the genus is Homo; the species is Homo sapiens!
A few additional points: The word species is both the singular and plural form of the word (e.g. one species or two species). Once an author has written the full species name in a scientific paper, article, text book, etc. the genus may be abbreviated by using its first letter. For example, the first time you refer to the green toad, use Bufo viridis but thereafter (except if you are beginning a sentence with the species) you can refer to the species as B. viridis.
Although not common, sometimes the name or abbreviation of the biologist (called the authority) who gave the organism the name follows the species name. For example, Ulmus americana L. tells us that Linnaeus (L.) named the American elm and Circotettix rabula Rehn & Hebard indicates the authors who first described this grasshopper
Finally, although the scientific name is usually a binomial, occasionally separate subspecies are recognized, making the scientific name a trinomial. For example, the subspecies of the fence lizard (Sceloporus undulatus) that inhabits rocky areas of eastern Colorado is Sceloporus undulatus erythrocheilus (the red-chinned lizard) while that found on the high plains Colorado and Nebraska is the northern prairie lizard (Sceloporus undulatus garmani).
Botanists sometimes recognize similar divisions but call them varieties instead of subspecies. So, although the peach and nectarine are both the species Prunus persica., the peach is Prunus persica var. persica while the nectarine is Prunus persica var. nucipersica. Note that the designator for variety (var.) is not italicized or underlined.
Checklist for Writing Scientific Names
q First word in species name is capitalized, second word is lower case.
q Scientific name is either italicized or underlined
Materials and Methods
This is often the most difficult section for students because of some of the rules and conventions followed in scientific writing. In writing a materials and methods section, you need to describe what you did in such a way that a fellow scientist can follow and duplicate your experiment.
- Use the third person and past tense.
- Describe what you did.
- Give enough information to tell the reader how you did the experiment but not so much as if you were writing a cookbook or lab manual.
- In field studies it is important include the locations and times that data were collected.
- Avoid the use of slang or jargon.
Good Example:
- Twenty-five µl of each sample were loaded onto a 10% polyacrylamide gel and subjected to electrophoresis for one hour at 120V.
(Note that the number 25 is spelled out because it begins a sentence and the abbreviation for microliters is used; everything is in third person and past tense.)
Bad Examples:
- Take 25 µl of each sample and load them on a 10% polyacrylamide gel.
(Do not tell the reader what to do, tell them what you did)
- Next I would take 25 µl of each sample and load them on a 10% gel.
(Avoid the first person; write in third person and past tense)
- 1. Load 25 µl of each sample on a 10% polyacrylamide gel.
- 2. Run the gel at 100 V for 30 minutes
- 3. Transfer the gel to nitrocellulose for one hour at 70V.
(Don’t make lists; describe what you did in a sentence)
- 25 µl of each of the 3 samples were then loaded on a 10% polyacrylamide gel.
(Don’t start sentences with numbers or abbreviations; also spell out numbers less than 10)
- Then we ran the proteins on a gel. (Slang)
One of the most difficult things in writing a Materials and Methods section is deciding how much detail to give the reader. Too much detail can make this section excessively long. You should try to be concise, but complete.
- Twenty five µl of each sample was drawn up and loaded onto the top of a 10% polyacrylamide gel. Buffer was then added to the upper and lower chambers and the electrodes were connected. The samples were then subjected to electrophoresis for one hour at 120V.
(Factually correct, but three times the length necessary)
- Samples were subjected to electrophoresis on a gel.
(Too little detail)
Checklist for Materials and Methods
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Results
The Results section of a paper presents a verbal description of the results of your experiment or investigation along with a summary of representative data in tables and figures. It is not merely a collection of tables and figures without explanatory text. If tables and figures are used, you should provide the reader with an interpretation of what a table or figure illustrates.
There are several keys to writing a good results section. These include:
(1) Present the results in an orderly sequence, using an outline as a guide for writing and following the sequence of the Methods section upon which the results are based.
(2) If tables and figures will be used to summarize your data, then construct these first (at least in draft form) and use them as a basis for writing the Results sections. Make sure that they are numbered and in the same sequence as they will be used in the text.
(3) Use good topic sentences for your paragraphs (a reader should be able to gather the main points by reading just the first sentence of each paragraph).
(4) Avoid redundancy and only present representative data from the tables and figures. Do not repeat, but summarize the information in tables and figures
(5) Avoid full sentence citation of tables and figures.
BAD: Results of the water quality analysis are shown in table 1.
GOOD: Nitrogen concentrations in the stream increased during 1999 (Table 1).
(6) Avoid repeating methods in the results section.
(7) Avoid discussion of results. In other words, present the facts but save interpretation of the significance of the results for the Discussion section.
(8) Use results of statistical tests as background material to support more general statements.
(9) Raw data are not usually included in scientific papers; however, your instructor may ask you to include these data in an appendix to your paper.
Figures and Tables
Although text is the preferred option of presenting data in scientific papers, figures or tables should be used if presentation of data in the text would be lengthy or ambiguous. Regardless of the format you use, do not present the data in more than one way within a paper (e.g., in a table and a figure). Condense data as much as possible, presenting means, ranges, and standard deviations rather than individual data points. Present only essential data, which should be guided by your objectives and outline.
Figures
Figures include graphs, maps, photos and technical diagrams. Presentation of data in graphs is generally more desirable than tables because they aid the reader in visualizing trends in the data. There are many different types of graphs, but the most common graphs used in scientific writing are scatter plots (Fig. 1), line graphs (Fig. 2) and vertical bar graphs (Fig. 3). Regardless of the type of graph you use, all contain similar elements.
(1) Axes. A graph consists of a horizontal axis and a vertical axis. Typically, values of the independent variable (the cause or what you manipulated) are plotted on the horizontal axis and values of the dependent variable (the effect or the outcome you measured) are plotted on the vertical axis.
(2) Labels. Both axes should be clearly and briefly labeled. Labels should include variables and units of measure.
(3) Tick marks. The axes should be evenly incremented. Tick marks should be placed on the axes and inside the line. They should include the range of data and should be kept to a minimum to avoid cluttering the figure.
(4) Figure legend. There should be a figure legend below the graph that briefly describes the information in the figure. It should be clear, concise, and informative. The figure legend should be understandable without reference to the text and answer, if appropriate, the questions “what”, “where”, “when” and “why”. Figures are numbered in order of reference in the text.
Table 1. A comparison of weight gains (g) in white rats fed on low-fat and high-fat diets for two months.
Low-Fat Diet High-Fat Diet
Sex t
N Mean Gain N Mean Gain
Males 12 2.4 11 2.9 1.42
Females 14 3.1 15 5.7 3.01*
*(P<0.05)
Tables
In contrast to figures, tables allow precise numerical presentation of data. As with figures, they should be concise and organized such that relations and trends in the data are evident without reference to the text. All tables contain similar elements.
(1) Title. Tables are numbered (Arabic numerals are generally used) in order of reference in the text. The title briefly describes the information presented in the table and is presented at the top of the table.
(2) Column and row headings. Column headings identify variables or data in each column below the heading. They contain variable names and units of measurements. Row headings identify entries in the rows to the right of the heading. Note that only the initial letter of words or phrases in column and row heading is capitalized.
(3) Body. The body contains the data presented in the table. Data should be presented so that similar elements read down (i.e., in columns). When presenting numbers, give only significant figures; within columns, align the decimal points of the numbers, the hyphens of ranges (e.g., 25-67) and plus/minus signs, place a zero before the decimal point of numbers less than 1 (e.g., 0.1, not .1) and enter numbers in a column under the column heading.
(4) Horizontal lines. Horizontal lines separate the table title from the column headings, the column headings from the subheadings, the column headings from the body, and the body from the footnotes. Do not use vertical lines in tables.
(5) Footnotes. Footnotes contain explanatory information.
Checklist for Results
q Figure legends below figure, figure axes are properly labeled.
q Table title above title, columns and rows are properly labeled.
q Results are displayed graphically and also explained in text.
q Use past tense .
q Data is analyzed, no raw data is presented.
Discussion
The discussion portion of the paper has fewer restrictions than other sections of a science paper. It is the section of the paper in which you interpret your data and draw conclusions regarding your hypothesis. In some respects, this is the most difficult section of the paper to write. You should not repeat the results section, but rather place your data in a broader context (i.e. why should anyone care about what you found?). Some key things that should always be included in the discussion are:
(1) An analysis of whether the hypothesis was supported by the results of your experiments. Your key findings should be emphasized first.
(2) A comparison of your results and your interpretation to the results and interpretations previously obtained by others. Integrate your data with what has been written previously in the appropriate literature. Does your data agree with current models or refute them? How have your experiments added to our knowledge of this phenomenon/organism/system?
(3) If your hypothesis was refuted, you must provide an explanation. You should also provide explanations of any unexpected results and describe any problems encountered during the experiment
(4) If you had problems during the experiment or if you are not satisfied with your results, tell how the methods could be altered to provide more definitive results
(5) Describe future experiments suggested by your results. You may wish to speculate on the broad meaning of your results to the field of biology.
An Example of a Discussion (from a paper by Rick Gillis & William Breuer)
Although these results were gained under laboratory conditions, they still establish physiological limits in terms of EWL for efts and newts. The ability of red-efts to tolerate dehydration better than newts might be adaptive in view of the problem of water loss confronting terrestrial amphibians and indeed, the ability to tolerate dehydration is probably the most wide-spread physiological adaptation to a terrestrial existence in amphibians as a group (Chew, 1961). (The hypothesis was that terrestrial efts should have lower rates of evaporative water loss (EWL) and be more tolerant to dehydration than aquatic newts. This paragraph fulfills objective number 1 from the above list.)
With respect to previous findings, it is interesting to note that the CAP of red-efts is similar to that of some other terrestrial urodeles (Ray, 1958) while tolerance to dehydration in newts parallels findings of Littleford et al. (1947) and Houck and Bellis (1972) for some of the more aquatic species of salamanders. (This paragraph integrates the experiment with the existing literature, fulfilling objective 2 from the above list.)
The observation that red-efts had higher rates of EWL than newts did not support the second hypothesis. (Unexpected results, hypothesis was refuted, fulfills objective number 3)
The explanation for these findings may rest with differences in body size. (Provides explanation of unexpected results, part of objective number 3)
As Table 1 shows, efts were on average considerably smaller than newts. Since rate of EWL in amphibians has been shown to be inversely proportional to surface area (Schmid, 1965), smaller animals should lose water from their skin more rapidly than larger ones. That the slopes of the regressions of rate of EWL on body mass in efts and newts differ significantly (-0.382 and -0.664 respectively) suggests, however, that these two forms respond differently in the test chamber. In efts, a small increase in mass leads to a greater reduction in rate of water loss than the same increment produces in newts. Such a reduction in EWL might help to offset the water conservation problems experienced by these small, recently metamorphosed juveniles.
The most probable explanation for the lower mass-specific rate of EWL in efts is that mass alone is not as good a predictor of surface area as it is in newts. Newts, although generally cylindrical, have large dorsolaterally compressed tails consistent with their aquatic mode of locomotion. Efts are more streamlined and possess tails that are cylindrical (and tapering) in cross section.
Although measurements were not actually made, it seems likely therefore that in specimens of equal mass, efts will have a lower surface area than newts and realize a concomitant reduction in rate of EWL. In light of these findings, it might be instructive if surface areas could somehow be measured so that newts and efts with similar values could be compared. With such a procedure, a researcher might determine if there were any differences in the abilities of the skins of these two forms to retard evaporative water loss. (Proposing future experiments and alterations in methods to provide more definitive results, fulfills objectives 4 and 5 from the above list)
*** NOTE: COMMENTS IN BOLD ARE FOR EXPLANATORY PURPOSES AND SHOULD NOT BE INCLUDED IN YOUR PAPER.
Checklist for the Discussion
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q Stated if hypothesis was supported or refuted q Compared results to previous observations using appropriate literature q Explained unexpected results or provided an alternative hypothesis if hypothesis was refuted. q Described or suggested future experiments. q Clear and logical flow of ideas.
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