SELECTION AND PREPARATION OF ORGANISMS 67 



to our understanding of general botanical principles. A process that can 

 be studied in sunflower or soybeans, however, leads to much broader 

 generalizations. Even in pure, fundamental, basic research, where prob- 

 lems are investigated only to increase knowledge, most of the problems 

 are "human problems." Any study of an unusual or unique organism 

 may be justified as satisfying curiosity, but the results often stand alone 

 as details and may never be incorporated into the general advance of 

 science. 



General comments on choice of organism 



These several features, then, are necessary or desirable in experimental 

 organisms. In the selection of an animal or plant for experimentation, 

 a period of reflection on these features may save complications later. Some 

 of these are considered without much thought, it is true; others are 

 commonly neglected. Once the various essential and desirable features 

 have been considered, there may still be a choice of organisms. In this 

 event the experimental biologist usually chooses the organism that is 

 the most convenient. 



In the selection of organisms for experiment, it is commonly possible 

 to consider the use of only part of an organism rather than the whole 

 organism. In the study of muscle contraction, it is better to dissect out 

 a muscle and throw away the rest of the frog because the rest of the 

 frog only adds to the complication. If we are interested in the photo- 

 synthesis of tomato plants, separate leaves or parts of leaves may be used 

 to avoid the necessity of maintaining all the other activities that nor- 

 mally go on at the same time as photosynthesis. 



The same general rules that govern the selection of species apply to 

 the selection of parts of organisms, although there is now the added 

 assumption that the removal of the part for study has not altered the 

 activity being studied. It usually seems, however, that the separation of 

 parts makes relatively little difference in the processes being measured. 

 Common sense, good judgment, and experience can he used to advantage 

 in deciding to use a part of an organism instead of the whole organism. 



Preparation of organisms for experiment 



This section includes a number of ideas important to the preparation 

 of biological materials for experiments. The list is intended as a set of 



