172 LIFE: ITS NATURE AND ORIGIN 



determinants in the gametes in such a way that the modifications 

 would be inherited," involved the action of hormones; the latter 

 were defined as special chemical compounds which take the place 

 of the imaginary gemmules in Darwin's theory of pangenesis and 

 of the "constitutional units" of Herbert Spencer. In stressing the 

 view that the theory of the hereditary transfer of somatic modifica- 

 tions is not in conflict with the theory of genie mutations, Cun- 

 ningham wrote: ". . . there are two kinds of variation in evolution, 

 one somatic and due to external stimuli, acting either directly on 

 passive tissue or indirectly through function, and the other 

 gameto-genic and due to changes in the chromosomes of the 

 gametes which are spontaneous and not in any way due to modi- 

 fications of the soma. Adaptations are due to somatogenic modi- 

 fications, non-adaptive diagnostic characters to gametogenic 

 mutations. It is a mistake to attempt to explain all the results of 

 evolution by a single principle." 



Professor W. H. Manwaring of Stanford University 14 stated: 

 "These studies suggest a Lamarckian rather than a Darwinian 

 world, or at least a world in which both Lamarckian and Darwin- 

 ian evolutionary mechanics are operative." (This refers to his 

 review). 



Henry Fairfield Osborn stated 15 in the third of a series of 

 addresses on the origin of species, that the theories of Buffon 

 (direct action of environment), Lamarck and Darwin, usually 

 regarded as contradictory, are really complementary, for they all 

 turn on the question of inheritance or transmission of individual 

 adaptation, which may furnish the key to evolution. "On the 

 affirmative side paleontology proves in the long run of geologic or 

 secular time that both Buffon and Lamarck, as well as Darwin, 

 were right in their main conceptions: organs starved by unfriendly 

 environment finally disappear; organs which do not pay their way 

 or are starved by disuse slowly drop out of the germ-plasm; vitally 

 essential organs are either absolutely stable or progressive. Why 

 not therefore concede the truth of the great conceptions of Buffon 

 and Lamarck, even if immediate inheritance by the germ is dis- 

 proved in the great majority of cases? Why not concede the still 

 greater conception of Darwin, misled as he was to time by the 

 marvelously rapid evolution of the germ-plasm witnessed in 

 artificial selections?" 



Professor Herbert S. Jennings 16 in speaking of the interaction of 

 cytoplasm and chromosomes in genetics and in development, points 



