Modification of Germinal Constitution of Organisms 145 



whole field been gone over and summarized, and yet one sees 

 no progress, nor can progress be expected from this method 

 of attack. Only precise experimental procedure can in any 

 way aid in the solution of the problem, and all too often the 

 experiments to test these theories, especially the earlier ones, 

 admit of diverse interpretations, so that they are in the main 

 inconclusive. 



In this chapter are presented some of the data accumu- 

 lated in recent efforts to gain precise experimental knowl- 

 edge of how germinal changes are brought about. I shall, 

 therefore, present in two divisions the data and conclusions 

 bearing upon the two supposed methods of change, with 

 such brief discussion and correlation of the already over- 

 discussed and over-correlated literature as may be necessary. 



THE TRANSMISSION OF SOMATIC VARIATIONS 



It has been proved that variations do arise primarily in 

 the germinal substance, and appear secondarily in the soma ; 

 but can it be proved that modifications arising in the 

 soma are transmitted to and incorporated into the germinal 

 constitution and appear in subsequent generations? It is 

 apparent that properly planned and conducted experiments 

 are alone of service in the attempt to solve this question. 



It in no wise strengthens the position of the supporters 

 of the theory of the peripheral origin of variations to present 

 an extensive array of examples not expKcable excepting 

 through the use of this idea, and even though it "does 

 explain" and "may explain" a huge array, or even all of the 

 problems of evolution, it does not thereby become a proven 

 truth. Special creation equally well ex|.:>lains all the 

 phenomena, if certain assumptions be accepted as true. 

 However, not until this or any other form of transmis- 



