320 BIOLOGICAL LECTURES. 



e. Hyatt on Acquired Characters. 



Professor Hyatt was the first to demonstrate a wonderfully 

 complete parallelism between the ontogenetic and the phylo- 

 genetic series, and he has presented the paleontological argu- 

 ment in terms that seem, to many at least, to be beyond 

 controversy. With all respect to Professor Hyatt's monu- 

 mental work, I must say that I find nothing in the evidence 

 that compels one to take his view of acquired characters. 



" We have been unable " [says Professor Hyatt] " to find any char- 

 acters which were not inheritable in some series. The behavior 

 of all characteristics which have been introduced into any series of 

 species shows them to be subject to the law of acceleration, in what- 

 ever way they have originated, whether primarily as adaptive char- 

 acters, according to our hypothesis, or by natural selection and 

 through the combination of the sexual variations, as supposed by 

 Weismann." 1 



This is a very sweeping statement, at least in implication. 

 I can hardly believe that the author would have us understand 

 that acquired characters are just as readily and invariably trans- 

 mitted as congenital characters ; and yet, if that is not the 

 argument, there is no argument there. Nothing is more cer- 

 tain than that, in living forms accessible to direct experimental 

 test, acquired characters are not invariably, if at all, trans- 

 missible. Demonstrations have been sought for, but so far 

 without avail. Unless the Arietidcz are a wholly exceptional 

 group, we must conclude from the above statement that all the 

 characters found were of congenital origin, and that no acquired 

 characters were recognized. It is easier to believe that such 

 characters were overlooked than to believe a miracle. 



The lazv of acceleration established by Professor Hyatt is 

 complemental to the biogenetic law formulated by Fr. Mliller 

 and Haeckel, and both laws rest on the theory of germ 

 continuity, as formulated by Weismann. Logically, neither of 

 these laws implies the transmission of acquired characters. 

 That is an assumption which has never been reconciled with 

 the fundamental law of the genetic continuity of germs. The 



1 " Genesis of the Arietidae,"p. 43, Mem. Mus. Comp. Zool., Cambridge, 1889. 



