IOWA ACADEMY OF SCIENCES. 35 



that is, it mast have a survival value. But many paleoii- 

 tolotvical series show the origination and gradual increase 

 in a large number of individuals simultaneously of charac- 

 ters which in their first stages could have possessed no 

 utility, and only after many generations reached a suffi- 

 cient degree of development to have a survival value. 

 Such progressive (ulaptatlons are regarded by the Neo-Lam- 

 arckians as positively disproving "the all-sufficiency of 

 natural selection." 



We are now in position to appreciate a dilemma into 

 which we have fallen, which reminds us forcibly of the 

 inadequacy of our present knowledge of this subject. If, 

 as held by the Neo-Darwinians, acquired characters are 

 not transmissible, then such progressive adaptations as 

 those mentioned above cannot be explained. If, on the 

 other hand, as held by the Neo-Lamarckians, acquired 

 characters are transmissible, then the method of such 

 transmission remains to be explained. In the words of 

 Osborn, "If acquired variations are transmitted, there must 

 be therefore some unknown principle in heredity; if they are 

 not transmitted, there must be some unknown factor in 

 evolution." 



For several years biologists have been trying to find 

 some factor or factors of evolution that would bridge over 

 the apparent gap between Neo-Lamarckism and Neo-Dar- 

 winism. Three investigators, Morgan, Osborn and Bald- 

 win, have independently brought forward an idea which 

 seems at least in part to accomplish this result. Baldwin, 

 who has most fully elaborated this theory, has applied to 

 it the name of orthoplasy. Account is taken of the 

 undoubted fact that changes in the environment product 

 important modifications in individuals, although such 

 acquired characters are not assumed to be transmissible. 

 The acquirement of characters in this way enables the 

 individual to meet changes in the environment which 

 without them might be so unfavorable as to cause their 

 extermination. They thus live to produce offspring, 

 which, although they do not inherit the acquired charac- 

 ters, develop them independently under the infiuence of 



