109 
1888-89.] Mr J, A. Thomson on Theory of Heredity. 
quoted as an illustration. Or, in the third place, apparent excep- 
tions to Weismann’s conclusion have been shown by him to he 
rather corroborations, by tracing them hack to an internal not 
external origin, and interpreting them as primary or secondary 
results of original germinal variations. 
Not only has this conclusion as to the non-inheritance of acquired 
characters run counter to the presuppositions of many naturalists, 
not to speak of the laity, hut if it is true, it literally takes the 
ground from under the feet of those who have based their theory 
of evolution upon the postulate that organisms could hand on as 
a legacy their individually acquired gains. Weismann’s theory, 
though accepted by authorities like Ray Lankester, has given rise 
to much criticism, part of which must he noticed. That the case 
is not yet surrendered may be seen from the very title of Professor 
Eimer’s recent important work, The Origin of Species , on the Basis 
of the Inheritance of acquired Characters , according to the Laws of 
Or game Growth. 
Criticism of Weismann. 
(1) Various naturalists have brought forward what appear to 
them to he examples of the genuine transmission of indi- 
vidually-acquired characters. Thus Detmer and Hoffmann 
among botanists, and Eimer among zoologists, may be quoted. 
The latter especially gives numerous examples to prove the 
untenability of 'Weismann’s position. To some of the 
instances urged against him, Weismann has replied ; hut as 
each case has to he carefully tried on its own merits, and 
as sufficient decisive experiments are still awanting, the 
matter lies beyond the sphere of the present paper. 
(2) Virchow has urged against Weismann what appear to him 
to be cases of the direct inheritance of climatic changes and 
pathological variations. But he appears to differ from 
Weismann in his definition of acquired characters, which 
for the latter do not include anything that can reasonably he 
traced hack to a germinal variation. Ziegler has discussed the 
whole question of the inheritance of pathological characters, 
and comes to a conclusion harmonious with that of Weis- 
mann, Nor are the slow results of acclimatisation good 
