Organic Evolution , Darwinism and the Genesis of Species. 21 
unchanged, the reproduction cells. Weismann’s theory has 
been opposed with considerable ingenuity and skill by 
Mivart, in his “ Recent Essays,” and by Spencer, in the 
Contemporary Review/for February, March, and May, of 
this year (1893). The question of its validity would appear 
to be one of fact. If acquired characters can be shown to 
be transmissible, the germ-plasm theory falls to the ground. 
The solution of “nature’s organic riddle,” as Mivart calls 
it, seems to me to be brought much nearer by the contri¬ 
butions of one or another of the newer schools of evolution. 
The neo-Lamarckian school—of which Spencer is a prom¬ 
inent representative — marches in the right direction. Too 
little importance was attached to the significance of individ¬ 
ual functiqn, and to the influence of environment and habit, by 
the earlier evolutionists. That these factors are now obtain¬ 
ing a proper recognition is unquestionably an important 
advance. 
Still more important are the conclusions of Niigleli, 
Eimer, Gray and Cope, which go to show that variation 
takes place along a few definite lines, and that the origin 
of species is to be sought in the development of the inter¬ 
nal condition of the species, which environment and selection 
influence, but do not control. Another most important 
contribution to the question will be found in the views 
recently expressed by Professor Geddes. This naturalist 
holds that hitherto all theories have started with the indi¬ 
vidual as a unit, making the origin and differentiation of 
the structures and functions of the individual the primary 
problem, giving a secondary place to the differentiation of 
reproduction and species — i. e. as regards processes. This, 
according to Geddes, is an artificial and unnatural view. 
He lays great stress on the species-maintaining process, 
holding that we must keep in mind the living continuity 
of the species, which he affirms is a continuous underlying 
chain of unicellular reproductive units to which the individ¬ 
ual differentiation is only subsidiary. But whatever value 
may be assigned to the various forms and modifications of 
