PRESIDENTIAL ADDKKSS. T)0 



cause of the modifications that actually take place? Weis- 

 mann's English followers deny this and say that such modifi 

 cations are due to the selection of accidental variations in the 

 germ, and so in all cases. If the term "acquired" is to be 

 any further refined away, then discussion is useless, for it is 

 not a mere dispute about a word that interests us, but the 

 fundamental question whether external conditions do or do not 

 permanently and progressively influence the development of 

 organic beings. 



THE AMERICAN ' ' SCHOOIv. ' ' 



Probably the strongest arguments that have been brought 

 forward upon the affirmative side of this question are those 

 derived from paleontology, and singularly enough, hitherto, so * 

 far as I am aware, this view of the question has been presented, 

 with the single exception of Kowalevsky, entirely by Ameri 

 cans. This work was not done under the stimulus of Weis- 

 mann's writings, because most of it was already accomplished 

 .before his essays appeared. 



As far back as 1866 Prof. Alpheus Hyatt read a paper "On 

 the Parallelism between the different stages of life in the 

 Individual and those of the entire Group of the Molluscan 

 order Tetrabranchiata, " * in which were foreshadowed the 

 views more definitely expressed in 1880 in his papers " Upon 

 the Effects of Gravity on the forms of shells and animals, ' ' f 

 and ' ' The Genesis of the Tertiary Species of Planorbis at 

 Steinheim." J In these papers Professor Hyatt showed the 

 moulding influence of what in this case happened to be an 



*Mem. Bost. Soc. Nat. Hist., Vol. I, p. 193. (Read Feb. 21, 1866). 

 fProc. A. A. A. S., 1880, p. 527. 



jMem. Bost. Soc. Nat. Hist., Fiftieth Anniversary, 1880. Second 

 Memoir. 



