1894.] | Neo-Lamarckism and Neo-Darwinism. 677 
‘somatogenic’ characters cannot be transmitted, or rather, that 
those who assert that they can be transmitted, must furnish 
the requisite proofs.” That is: changes in the soma-plasm 
are not transmitted; acquired characters are changes in the 
soma-plasm; therefore, acquired characters eannot be trans- 
mitted! Or, to use Weismann’s shorter phrase, “Since the 
characters * * * are hereditary, the term [‘acquired’] 
cannot be rightly applied to them!” Surely, Neo-Darwinism 
is impregnable! 
Weismannism has unquestionably done much to elucidate 
some of the most intricate questions of biology, and it has 
weeded the old hypotheses of much that was ill-considered 
and false. It has challenged beliefs which have been too easily 
accepted. Its value to the science of heredity upon its biolog- 
ical side is admitted, and its explanation of the meaning of 
sex is one of the best of all contributions to the philosophy of 
organic nature. It has suffered, perhaps, from too ardent 
champions, and its great weakness lies in its stubborn refusal 
to accept an important class of phenomena associated with 
acquired characters, a sufficient explanation of which, it seems 
to me, could be assumed without great violence to the 
hypothesis. 
Most Neo-Lamarckians accept much of Weismann’s teach- 
ings. But, while there are comparatively few who believe 
that mutilations are directly transmissible, there is a general 
and strong conviction that many truly acquired characters are 
hereditary, and there seems to be demonstrable evidence of 
it; and while sex variation is fully accepted, it logically 
follows, if acquired characters are hereditary, that much 
variation is due directly to external causes. Perhaps the 
habit of thought of most Darwinians and Neo-Lamarckians 
is something as follows: 
All forms of life are mutable. Variation affords the mate- 
rial from which progress is derived. Variation is due to 
sexual union, changed conditions of life, panmixia or the ces- 
sation of natural selection, and probably somewhat to direct 
use and disuse. There is an intense struggle for existence. 
All forms or variations useful to the species tend to m en e 
