858 The American Naturalist. [October, 
of so many who have become his followers in America that a 
special school came into existence known as the Neo-Lamarck- 
ian and also as the American School. My own prejudices 
have inclined me to that school. Nevertheless, when I have 
divested myself of such prejudices as well as I could, I have 
been compelled to admit that the evidence of the heredity of 
acquired characters was rather weak. There was, indeed, evi- 
dence for, as well as against, but that against the doctrine of 
the transmissibility of acquired characters seems to be the most 
weighty. 
It is to be understood that the acquired characters consid- 
ered in this connection are such as have been developed dur- 
ing post-natal life as a result of endeavors of the animal 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 conse- 
quently the transition from the form not possessing the char- 
acter to one having it is rapid. The evidence adduced has not 
been conclusive, to say the least. There is, apparently,a germ 
of truth in the proposition that acquired characters are trans- 
mitted, but in a modified sense, and the case has been weak- 
ened rather than strengthened by the evidence offered. 
The evidence for inheritance of acquired characters was fre- 
quently given by Cope, and in his last published work—“ The 
Primary Factors of Organic Evolution ”—he marshalled the 
testimonies of many witnesses with his accustomed skill. He 
evoked “ evidence from embryology,” “evidence from paleon- 
tology,” “evidence from breeding ;” he considered the “ char- 
acters due to nutrition,” “characters due to exercise of func- 
tion,” “characters due to disease,” “ characters due to mutila- 
tion and injuries” and “ characters due to regional influence ; ” 
he inquired into “ the conditions of itheritance,” and he fought 
against the “objections to the doctrine of inheritance of ac- 
quired characters.” I have gone over all this evidence and 
yet I have not been convinced that the eontention has been 
sustained that character acquired during the external life of 
an animal are transmitted. Many cases are alleged to sustain 
_ the “inheritance of characters due to mutilation and injur- 
