470 PRIMARY FACTORS OF ORGANIC EVOLUTION. 



American Association for the Advancement of Science, 

 and by Prof. H. F. Osborn in 1891 in the Cartwright 

 lecture before the New York College of Physicians. 



It is evident that evolutionists are reaching greater 

 harmony of opinion on the question of inheritance. 

 In fact, the discussion is sometimes a logomachy de- 

 pendent on the significance which one attaches to 

 the term "acquired characters." Thus Von Rath 1 re- 

 marks : "There is nothing in the way of the opinion 

 that by the continued working of such external in- 

 fluences and stimuli the molecular structure of the 

 germ-plasma also experiences a change which can lead 

 to a transmission of transformations. Above all, it 

 ought not to be forgotten in this case that the somatic 

 cells are in no way the first to be modified by the stim- 

 ulus, and that then by some sort of unexplained pro- 

 cess (pangenesis or intracellular pangenesis), this 

 stimulus is transmitted gradually by these cells to the 

 plasma of the germ-cells. The influence on the germ- 

 plasm is rather a direct one, and if by continued in- 

 fluence a transformation of the structure of this plasm 

 takes place and transmission occurs, we have then 

 simply a transmission of blastogenic, and by no means 

 of somatogenic characters, and therein is not the 

 slightest admission of the transmission of acquired 

 characters.' 5 



This paragraph contains an admission of the doc- 

 trine of diplogenesis, and does not regard the phe- 

 nomena as including a transmission of acquired char- 

 acters. Nevertheless the stimuli traverse the soma in 

 order to reach the germ-plasma. Such an energy is 

 evidently then not of blastogenic origin, although it is 



IBerichte dcr naturforschenden Gcsellschaft zu Freiburg in Baden, Bd.VI., 

 Heft 3 . 



