SELECTION AND PREPARATION OF ORGANISMS 63 



without success to detect some activity in broken-up cells of sunflower, 

 the ordinary geranium, and a few other plants. We now know that even 

 the best of modern technique for some reason fails to provide active 

 chloroplasts from these species. If Willstatter and Stoll had happened to 

 try spinach, the whole course of research in cell metabohsm might have 

 been changed drastically. 



Now, what does this prove? Nothing, of course. A few isolated, spec- 

 tacular examples need not be convincing, and indeed, they were chosen 

 partly because they are exceptional. It might be said that none of these 

 investigators could forsee the value of a particular organism, nor the 

 great effect it would have on future science. This is true, but Drosophila 

 and Chlorella were chosen for a set of very good common-sense reasons. 

 Several other available organisms had obvious disadvantages by com- 

 parison. The choice of experimental organisms is an important one, and 

 a number of considerations are well worth weighing. 



In addition to the strict scientific aspects of choosing the organism 

 which will best answer the question, there is no harm in remembering 

 the feelings of the general public. Experiments on animals are very 

 necessary, but they may seem cruel to the layman who has had little 

 experience or training and who does not understand experimental re- 

 search. Sometimes a careful choice of experimental animals can make 

 the layman feel better, without in any way damaging the experiment. 

 Occasionally a group of do-gooders becomes fanatical about the use of 

 animals in research. Picturing the biological scientist as a cruel, in- 

 humane monster without a conscience, they even apply pressure to legis- 

 lative bodies urging the passage of laws which would in fact stifle medical 

 research, but these same persons are as willing as anyone else to accept 

 modern medicine's ability to keep them alive longer. Fortunately, the 

 fanatics are a minority. Several organizations such as some Humane 

 Societies and the Animal Welfare League, having biologists among their 

 memberships, have reasonable and worthy aims. Actually, modern biolo- 

 gists have an appreciation of animal life that the fanatics can never 

 achieve. They never condone needless cruelty. For personal reasons, as 

 well as for the reason that it makes experimental results more reliable, 

 the biologist treats his animals extremely well. We can ignore the 

 fanatics, but a studied antagonism is neither necessary nor profitable. 

 Within the limits imposed by the research problem itself, it is often pos- 

 sible to select a generally acceptable animal. 



The following paragraphs describe some of the criteria which must 

 be remembered in choosing experimental organisms. The list is divided 



