240 
question. It is not the fore limbs that are 
retarded in man, but the hind limbs have 
become enlarged (compare the adult and 
the infant). There is not retardation of 
the jaws, but a special teleological adapta- 
tion. Man has for the most part at least 
discontinued the use of his teeth for war- 
fare, and as a result of diminished use the 
canines have become reduced and the dia- 
stemata of the dental series been obliterated. 
The brain has grown after birth and become 
enlarged, and as a consequence 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 became 
atrophied. The ecarinate rounded volu- 
minous ecalvarium is the result. 
It has been claimed that the young of 
higher species ‘are constantly accelerating 
their development.’ In many, however, de- 
velopment is retarded, inasmuch as infancy 
and juvenility are prolonged far beyond the 
periods observed in our simian relatives. 
Such examples as this give cause to be- 
lieve that the ‘law of acceleration and re- 
tardation’ has been at least unduly extend- 
ed. 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 mean- 
ing one gives the word. 
The transmission of acquired characters 
was one of the accepted and most cherished 
dogmas of Cope, and the belief in trans- 
missibility of such characters is an essential 
of the creed of so many who have become 
his followers in America that a special 
school came into existence known as the 
Neo-Lamarckian and also as the Amer- 
ican School. My own prejudices have in- 
clined me to that school. Nevertheless, 
when I have divested myself of such preju- 
dices as well as I could, I have been com- 
SCIENCE. 
[N.S. Vou. VI. No. 137. 
pelled to admit that the evidence of the 
heredity of acquired characters was rather 
weak. There was, indeed, evidence for, 
a well as against, but that against the doc- 
trine of the transmissibility of acquired 
characters seems to be the most weighty. 
It is to be understood that the acquired 
characters considered in this connection are 
such as have been developed during post- 
natal life asa result of endeavors of the ani- 
mal or of the influence of external agencies. 
The evidence presented has been mostly in 
support of the contention that the characters 
acquired have been directly inherited by 
offspring, and consequently the transition 
from the form not possessing the character 
to one having it israpid. The evidence ad- 
duced has not been conclusive, to say the 
least. There is, apparently, a germ of truth 
in the proposition that acquired characters 
are transmitted, but ina modified sense, and 
the case has been weakened rather than 
strengthened by the evidence offered. 
The evidence for inheritance of acquired 
characters was frequently given by Cope 
and in his last published work— The Pri- 
mary Factors of Organic Evolution,’—he 
marshalled the testimonies of many wit- 
nesses with his accustomed skill. He 
evoked ‘evidence from embryology,’ ‘ evi- 
dence from paleontology,’ ‘evidence from 
breeding ;’ he considered the ‘characters 
due to nutrition,’ ‘characters due to exer- 
cise of function,’ ‘characters due to dis- 
ease,’ ‘characters due to mutilation and 
injuries,’ and ‘characters due to regional 
influence’; he inquired into ‘the con- 
ditions of inheritance,’ and he fought 
against the ‘ objections to the doctrine of 
inheritance of acquired characters.’ I 
have gone over all this evidence and yet I 
have not been convinced that the conten- 
tion has been sustained that character ac- 
quired during the external life of an ani- 
mal are transmitted. Many cases are al- 
leged to sustain the ‘inheritance of charac- 
