TRANSFORMISM 227 



environment. The latter must therefore react on the 

 germ-plasm, but the environment formed by the 

 bodily tissues which surround the germ-cells may also 

 so react : thus the germ-cells may be affected by such 

 bodily changes as differences in the supply of nutritive 

 matter, for instance. The offspring may deviate from 

 the parental structure as the result of structural modi- 

 fications acquired by the parent during its own lifetime, 

 and, even if the filial deviation were not of the same 

 nature as the parental modification, its inheritance would 

 be an adequate cause of some degree of transmutation. 



It is, however, certainly difficult to prove that 

 organisms transmit to their progeny the same kinds of 

 deviation from the specific structure that they them- 

 selves acquire as the result of the action of the envi- 

 ronment. Even if they did transmit such acquired 

 deviations, it does not seem clear that this kind of 

 inheritance alone would be a sufficient cause of the 

 diversity of forms of life that we do actually observe 

 in nature. Change of morphology would indeed occur, 

 but we should expect to find insensible gradations of 

 form and not individualised species. Let us suppose 

 that Lamarckian inheritance acts for a considerable 

 time on two or three originally distinct species in- 

 habiting an isolated tract of land, and let us suppose 

 that we investigate the variations occurring among all 

 the organisms which are accessible to our observation 

 with respect to some one variable character. 



The diagram A represents what would seem to be 

 the result of this process of transmutation. The 

 numbers along the horizontal line are proportional 

 to their distance from o, the origin, and represent the 

 magnitude of the variation considered ; and the 

 height of the vertical lines represents the number of 

 organisms exhibiting each degree of variation. We 



