HEREDITY. 167 



transmission of bodily characters a subject of more pro- 

 found study, have general and national psychology been 

 impelled to estimate the influence of heredity in the 

 province of the mind, and demonstrate how, in the vari- 

 ous races and families of nations, the molecular peculiari- 

 ties 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 hered- 

 ity must be looked for in the. process of reproduction. 

 The molecular motions and disturbances, the inconceiv- 

 ably 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. If a 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 aiira seminalis was 

 refuted, also a separation of material portions of the pa- 

 rental organisms. It is still a mechanical process which 



