1897,] A Chapter in the History of Science. 857 
Now, in the light of various cases observed, where members of the 
same species or brood are found at adult age to differ in the number of 
immature characters they possess, we may conclude that man originated 
in the following way : that is, by a delay or retardation of growth of the 
body and fore limbs as compared with the head ; retardation of the jaws 
compared with the brain case, and retardation in the protrusion of the 
canine teeth. 
There is a good reason for thinking that fallacy is involved 
in this argument, and that quite a different interpretation 
should be put on the evolution of charasters in question. It 
is not the fore limbs that are retarded in man, but the hind 
limbs have become enlarged (compare the adult and the in- 
fant). There is not retardation, of the jaws, but a special tele- 
ological adaptation. Man has, for the most part, at least, dis- 
continued the use of his teeth for war-fare, and, as a result of 
diminished use, the canines have become reduced and the 
diastemata of the dental series obliterated. The brain has 
grown after birth and become enlarged, and, as a conse- 
quence, the brain case has extended forward—the reverse of 
what occurs in the apes. Concomitantly with the diminished 
use of the teeth and jaws, the masseter and temporal muscles 
have become reduced, and the sagittal and lambdoidal ridges 
have consequently become atrophied. The ecarinate rounded 
voluminous calvarium is the result. 
It has been claimed that the young of higher species “are 
constantly accelerating their development.” In man, how- 
ever, development is retarded, inasmuch as infancy and ju- 
venility are prolonged far beyond the periods observed in our 
simian relatives. 
Such examples as this give cause to believe that the “law 
of acceleration and retardation” has been at least unduly ex- 
tended. Acceleration and retardation are, however, to a large 
extent, terms which express facts of evolution; whether the 
word law is applicable may depend on the meaning one gives 
the word. 
The transmission of acquired characters was one of the ac- 
cepted and most cherished dogmas of Cope, and the belief in 
transmissibility of such characters is an essential of the ereed 
