SEXUAL SELECTION 409 



It is a truth that loses none of its force by repetition that in labora- 

 tory observation of animals, the laboratory conditions do not always 

 accurately represent the conditions in nature, and that the deportment 

 of an animal in the laboratory may not be exactly the same as its deport- 

 ment in nature. The failure of some relatively high animals to breed 

 in captivity is a case in point, and this again calls attention to the 

 importance of a group of afferent impulses rather than a single impulse 

 in determining the response of animals. Some subtle influence of the 

 natural environment is lacking in the conditions obtaining in captivity, 

 and the normal deportment of the animals is modified in at least one 

 important detail. Other animals have a nervous system of sufficient 

 plasticity to adjust themselves to the changed conditions of the labora- 

 tory or zoological garden. But the laboratory experimenter is now, and 

 will be for some time to come, dependent upon the data of close and 

 accurate observers of animal life in the field for his basis of comparison. 

 And until the laboratory worker is certain that the deportment observed 

 in the laboratory corresponds to that in nature, his analysis is not bio- 

 logically accurate. 



It is probably true, as Professor Cockerell 9 suggests, that no man 

 will ever be able accurately to tell the complete story of Wallace's life 

 work, even on its biological side alone, using the word in its widest 

 sense. It is an evidence of the genius of Darwin and of Wallace that 

 each was able to get such a fundamental grasp of the phenomena of 

 nature as to afford problems for workers in other lines apparently far 

 removed from their own. The experimental physiologist has had rela- 

 tively little to say in -regard to evolution as yet, and is perhaps in no 

 position to settle dogmatically any particular problem now. But physi- 

 ology has a direct contribution of interest to the worker in certain phases 

 of a much wider problem. Specialties multiply, new and confusing 

 terminologies develop, and the point of view ever tends to become nar- 

 row. Biologists pursuing one specialty have more and more difficulty in 

 communicating to biologists in other lines of work, the particular results 

 in their own. And biologists are almost unintelligible to workers in 

 physics and chemistry. Yet science is a unit, and there can be no lasting 

 truth developed in one field unless it is in accord with truth in every 

 other field. The task of finding out what other workers have to offer 

 us is a huge and even insuperable one under present conditions. Some 

 hope of relief may be held out when the biologists get some of their 

 great generalizations reduced to simpler form, and consequently intelli- 

 gible to the scientific multitude. At present, the theory of evolution 

 seems to be the most promising common meeting place to which biol- 

 ogists in all lines of work may bring their contributions for the judg- 

 ment and criticism of their brother workers. 



9 Science, 1913, N. S., XXXVIII., p. 871. 



vol. lxxxiv. — 28. 



