HEREDITY. 167 
sion of bodily characters a subject of more profound 
study, have general and national psychology been im- 
pelled to estimate the influence of heredityin the province 
of the mind, and demonstrate how, in the various races 
and families of nations, the molecular peculiarities of the 
brain, the tendency of character and intelligence of the 
individuals, and whole series of ideas, conform both in 
vigour and purport to the laws of heredity. 
It is manifest that the key to the phenomena of he- 
redity must be looked for in the process of reproduction. 
The molecular motions and disturbances, the incon- 
ceivably minute mechanical transfers which take place, 
do not, indeed, admit of observation. They are, however, 
no more “obscure” and “enigmatical,” as they are so 
readily termed, than the invisible, but not supernatural 
motions, on .the control and calculation of which the 
stately edifice of theoretic Chemistry and Physics se- 
curely rests, With the advance from asexual to sexual 
reproduction, and from the simple to the more perfect 
organisms, the difficulty of representation increases, but 
not that of abstract comprehension. Ifa low organism, 
a monad, divides itself; the divided individuals differ from 
the parent individual only in their inferior bulk, and the 
difference of their functions is, as to quality, nil. 
So, too, where gemmules and germs separate from a 
parent organism, the dower of the offspring is so large 
that identity in form and function of progenitor and 
progeny appears self-evident and natural. But the sexual 
reproduction of composite organisms is, as we have 
known since the old doctrine of the aura seminalis was 
.tefuted, also a separation of material portions of the pa- 
rental organisms. It is still a mechanical process which 
