What, then, were the unspoken rules of etiquette in the moral economy of Drosophila exchange? Reciprocity was one: the privilege of receiving stocks entailed the obligation to reciprocate. Exchange was an ongoing, low-level potlatch. Charges were not usually made for stocks, though the Morgan group did ask recipients to return mailing tubes and pay postage. [1] However, it was the custom to pay a dollar or two for stocks used for teaching. Since supplying stocks for teaching was not a reciprocal interaction between active researchers, it was gradually removed from the moral economy into the cash nexus. For example, W.M. Barrows insisted on paying Muller for stocks: "We have been the recipients of so many favors," he explained, "that I would much prefer to buy these outright." [2] When the supply system was formalized in the 1930s, requests for stocks for classroom use were routinely referred to commercial biological supply houses. [3] Nothing better illustrates the moral basis of the reciprocity.

Disclosure was a second rule: recipients of stocks were expected to tell donors what experiments they planned to do and to keep them informed of what the results were, especially if the results came a little too close to the donors' own line of work. Patterson, for example, told Stern what he knew about the structure of translocation stocks that he was sending, and asked Stern to tell him if he turned up anything interesting. [4] When Beadle and Stern swapped suppressor stocks, they also told all they knew about them and how they would be used, just to make sure no one's toes would be trod upon. [5] It was this custom of disclosure that made exchanges of stocks such an effective system of informal communication. Every stock carried with it news of future plans and projects. Exchange also nourished trust and defused suspicions that were entirely natural and healthy among producers who, because they did share tools, were always potential rivals. Failures to disclose were taken as serious reasons to worry about borrowers' intentions.

A third and fundamental rule was that while problems might be owned (temporarily) by individuals, tools could never be: they were the property of the whole community. Well, not quite. The skill and hard work that went into constructing very special tools - such as reagent stocks for mapping, triploids and attached-X mutants, and translocations - did entitle those who did the work to a degree of personal ownership. It was customary to get permission from the inventors of these valuable and versatile tools before using them, but it was taken for granted that permission would not be refused. The idea was that everyone would benefit from sharing tools that could be applied to more problems than any individual alone could dream up or carry through. It was improper to get mutants from colleagues in order to do faster or better what they had already begun. The idea was to enlarge the usefulness of tools by imagining new things to do with them. On the other hand, it was customary to put no restrictions on what was done with borrowed stocks, so as not to prevent workers from following up on serendipitous leads. Loaned stocks were fair game, and it was up to recipients to know when they might be intruding too far upon donors' own preserve - hence the importance of disclosure and continuing communication. Avoiding unintentional competition required care and tact, for the danger was ever present.

Bridges seems to have regarded even his unpublished work as public knowledge and was usually glad if someone saved him the trouble of writing it up. "Sure, go ahead and say in any publication anything you know I have," he once wrote Stern. "It is always better to have something in [print] than ignored!?" Sturtevant, too, liked to disclaim private ownership: "Use the inversion data . . . in any way you wish," he told Stern. "I'm not planning any general account of the things yet awhile, and of course I don't have any copyright on them." [6] Even Muller did not mind relinquishing results that were produced incidentally to other work (not, however, results that he might someday want to publish himself). [7]

No trade secrets, no monopolies, no poaching, no ambushes - these were the practical rules for establishing trust and working harmony among the fly people.

The rules of the game were social conventions, of course, and those who were not drosophilists born and bred had to learn the rules either by living among drosophilists for a time or by making mistakes and being corrected - a kind of moral apprenticeship. Gert Bonnier made such a mistake, for example, when he used Bridges's high-nondisjunction stock without informing Bridges what he was doing, or telling Otto Mohr, from whom he got the stock. This lapse made his intentions suspect. Stern hesitated when Bonnier later asked him for stocks, and wrote Mohr first to ask if Bonnier could be trusted. Mohr assured him that Bonnier's transgression was "due to lack of acquaintance with the scientific practice (coûtume) and not to bad will." A little gentle education was all that was needed:

It is clear, however; that there were fine points of etiquette that might well be puzzling to outsiders. How, for example, did one know what were "special" tools, to which proprietary rights adhered? At some point, clearly, Bridges's nondisjunction stock was dispersed in so many laboratories that it ceased to be personal and was a free resource to everyone; but when was that point reached? It was as if patents or copyrights had no fixed time limits. Another ambiguous case involved stocks that an individual had constructed or assembled for a special project. They could be reserved for the duration of the project, but when one thing led serendipitously to another; when had one project ended and another begun? In 1933, for example, Patterson declined to send Milislav Demerec some elaborately constructed stocks with multiple deficiencies, because he thought it would be unfair to the graduate student who was working on them. (Besides, Patterson thought, since Demerec only needed deficiencies at known loci, he could easily make his own by X-raying.) [9] When Bridges was in Leningrad without his flies and called on Stern to provide his Russian hosts with stocks, he was careful to say that the list of Stern's "current material" would be for his eyes only and off limits. [10] In the Drosophila Information Service "personal" stocks were listed separately to make clear that they were not yet freely available.

Limited proprietary rights applied not only to constructed stocks but to found objects: for example, wild Drosophilas collected in the field. Since collecting took time and skill, the rules of reciprocity, disclosure, and public ownership applied. In the late 1930s, for example, Sturtevant and Patterson swapped hundreds of flies collected in different regions of the American West, dividing up species that were of particular interest to one or the other. Both parties, however, felt free to exploit unexpected windfalls. Sturtevant told Patterson not to mistake his request for D. pseudoobscura as "a 'keep out' sign," but there was no need: Patterson knew he was free to work on anything of interest that turned up in any stocks that Sturtevant sent him, and he expected Sturtevant to do the same with the Texas flies that he sent to Caltech. They agreed that after the two of them had had a crack at the new material, they would then make everything available for general use on the Drosophila exchange. [11] It was not always pleasant to be generous, as Maydelle Bishop reported to Muller: "It's like pulling eye teeth to get the flies from him [Patterson], although all he does is to . . . look for sex ratios. It broke his heart to send the pseudo-obscura group to Caltech. He can feel like a martyr indefinitely over that since one stock showed a high female to male ratio." [12]

Conflicts could not always be avoided by generosity and disclosure, however. Ambiguities were inherent in the nature of the tool and in the ways it was used. Drosophila problems were so closely related to one another and so likely to unfold in unexpected ways that even with the best intentions two groups could easily end up working on the same problem. The fundamental distinction between tool and problem, so simple in principle, was in practice often hard to make. Trick stocks could be applied to various problems, but they were also objects of study in themselves, and tool could easily and unexpectedly become object. Triploids, for example, could be used as tools to study dosage effects, but the problem of how they were formed by nondisjunction of homologous chromosomes was a problem in its own right. Similarly, mapping a section of chromosome was a routine preliminary to studying particular genes, but if mapping became an end in itself, then it was no longer a tool but an object of study. Drosophilists thus drifted unwittingly into competition. Moral ambiguities could be managed but never eliminated, and the rules of exchange were no substitute for personal tact and judgment. Every exchange of stocks was potentially a delicate probing of knowledge and intentions and an improvised negotiation of rights and interests.

For more Drosophila-related links, see the HMS Beagle Featured Essay "Extraordinary Little Beast."

The Interactive Fly - "a cyberspace guide to Drosophila genes and their roles in development." Sections include an introduction; What's New; Developmental Pathways Conserved in Evolution; Index of Genes (e.g., genes listed alphabetically, by biochemical function, by developmental function); Tissue and Organ Development; and Morphogenesis and Organogenesis of the Adult Fly. Hosted by the Society for Developmental Biology.

FlyView: A Drosophila Image Database - image database on Drosophila genetics and development, especially expression patterns of genes. The site is designed to be compatible with FlyBase. Sections include What Is FlyView?; Introduction to Drosophila; P Elements in Drosophila; a search page (with more than 2,100 pictures from enhancer-trap lines); a feedback page; links to other Drosophila pages and resources; and more.

Classic Papers in Genetics - links to, and notes on, some of the most important papers in genetics, including Mendel's 1865 "Experiments in Plant Hybridization"and T.H. Morgan's 1909 "What Are 'Factors' in Mendelian Explanations?" Other authors are William Bateson, Archibald Garrod, Walter Sutton, G.H. Hardy, Calvin Bridges, Herbert Muller, Oscar Riddle, and Sewall Wright. Papers are in PDF format; links are included for downloading the free Adobe Acrobat Reader software required to read and print them.

A 2D-PAGE Protein Database of Drosophila Melanogaster - selection of two-dimensional protein reference maps of the adult Drosophila melanogaster's major body parts, showing the variety and identity of proteins in the male or female head, thorax, or abdomen. Links are provided to literature references to the 2D-PAGE pattern of proteins during various stages of Drosophila melanogaster development; literature references to applications of 2D-PAGE in Drosophila melanogaster research; and a news page with updated information about the database.

Levin Lab Science Links - many Drosophila links, including FlyBase; Fly Labs; GIFTS; BDGP (Berkeley Drosophila Genome Project); the Encyclopeida of Drosophila; Flytrap - On-line P[GAL4] Enhancer Trap Database; P1 Library; Drosophila Resource Database; the Interactive Fly; and the Squashed Bug Zoo; plus links to NIH/NCBI resources; Four Corners Database; ZYGOTE; The Tree of Life; Protocols on the Web; the Genome Database; and much more.

Model Systems - in this HMS Beagle Cutting Edge dialogue, scientists, historians, and philosophers discuss the strengths and limitations of using Drosophila and other model organisms for developmental, genetic, and evolutionary studies.