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 heredity in 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. 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 aura seminalis was 

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

 rental organisms. It is still a mechanical process which 



