1896.] Lost Characteristics. 11 



Tachygenesis 1 in allusion to the general character of the phe- 

 nomena. 



In a late paper, 2 the writer reviewed Prof. Cope's and Haeck- 

 el's views of this law, and contrasted them with his own, and it 

 seems advisable to give these remarks again in this connection. 



Professor Cope has given the fullest explanation of this law, 

 but has joined it with retardation. Thus, from his point of 

 view, if I rightly understand him, inexact parallelism in de- 

 velopment or failure to reproduce any hereditary characteristics 

 is due to a tendency which appears in organisms and works in 

 parallel lines with acceleration, the law being in his concep- 

 tion of a double nature. Thus he says, on page 142 of his 

 " Origin of the Fittest," " The acceleration in the assumption 

 of a character progressing more rapidly than the same in 

 another character, must soon produce, in a type whose stages 

 were once the exact parallel of a permanent lower form, the 

 condition of inexact parallelism. As all the more comprehen- 

 sive groups present this relation to each other, we are com- 

 pelled to believe that acceleration has been the principle of 

 their successive evolution during the long ages of geologic 

 time. Each type has, however, its day of supremacy and per- 

 fection of organism, and a retrogression in these respects has 

 succeeded. This has, no doubt, followed a law the reverse of 

 acceleration, which has been called retardation. By the in- 

 creasing slowness of the growth of the individuals of a genus, 

 and later and later assumption of the characters of the latter, 

 they would be successively lost. To what power shall we 

 ascribe this acceleration by which the first beginnings of 

 structure have accumulated to themselves through the long 

 geologic ages, complication and power, till from the germ that 

 was sea rcely born into a sand lance, a human being climbed the 

 complete scale, and stood easily the chief of the whole." And 

 again, on page 182 of the same work : "Acceleration signifies 

 addition to the number of those repetitions during the period 



'"Phylosenv of an Acquired Characteristic." Proc. Am. Phil. Soc Philadel- 

 phia, XXXII, Xo. 143. 



2 " Bioplastology and the Related Branches of Biologic Research." Proc. Bost. 



So.-. Nat' Hi-:.. XXVI, p. 77-81. 



