3 o 2 Problems of Organic Adaptation 



the intimate and minute adaptations found in organs, tissues, 

 and cells, and we shall consider first, inherited adaptations, 

 and later, acquired ones. 



Our object is not to catalogue and describe the multi- 

 tudes of adaptations which have been observed among 

 animals and plants, but rather to find an explanation of their 

 origin. However, since some recent writers have adopted 

 the method of explaining adaptations by explaining them 

 away and have solved the problem of their origin by deny- 

 ing their existence, it seems advisable to review some of the 

 more striking fitnesses that are found among living things 

 and especially among animals. 



Let us begin by freely admitting that under the influence 

 of the doctrine of supernatural design there has been a 

 marked tendency to exaggerate the frequency and the per- 

 fection of organic adaptations. Many naturalists have seen 

 adaptations where they do not exist and have invented 

 environmental conditions to fit these fanciful adaptations, 

 and when the usefulness of any structure or function could 

 not be made probable even by these means, it was always 

 possible to assume that this was due merely to our ignorance 

 of the real functions of the part in question or the real 

 needs of the organism. Sometimes the purely mechanistic 

 results of necessary physical, chemical, and biological con- 

 ditions have been regarded as special adaptations, and in 

 general, the attitude of those who are looking everywhere 

 for adaptations has not been very critical. 



But when we are assured by some modern critics that all 

 adaptations can be explained away in this manner, is it not 

 evident that extravagant and uncritical opinion has swung 

 to the other extreme? Adaptations may not be universal, 

 they may not be perfect, but that they are very numerous 

 and frequently so delicately adjusted to needs as to excite 



