538 
HEREDITARY INFLUENCE. 
might engender an elephant, the squirrel might be the pro- 
geny of a lioness, the tadpole of a tapir. The law, however, 
is constant. During thousands of years the offspring has 
continued to exhibit the structure, the instincts, and all the 
characteristics of the parents. Every day some one ex- 
claims — as if the fact surprised him — “ That boy is the very 
image of his father !” yet no one exclaims, ec How like that 
pug dog is to its parent \” Boys or pug dogs, all children 
resemble their parents. We do not allude to the fact out of 
any abstract predilection for truisms, but simply to marshal 
into due prominence an important truth, on which the whole 
discussion of heritage must rest. The truth is this ; Con- 
stancy in the transmission of structure and character from 
parent to offspring, is a law of nature. 
That this truth is not a truism we shall show by at once 
contradicting, or at least qualifying it. The very same ex- 
perience which guarantees the constancy, also teaches, and 
with almost equal emphasis, that this constancy is not abso- 
lute. Variations occur. Children sometimes do not resem- 
ble their parents ; which accounts for the exclamation of 
surprise when they do resemble them. Nay, the children 
are sometimes not only unlike their parents, they are, 
in important characteristics, unlike their species. We 
then call them deformities or monsters, because while their 
species is distinguished by having four legs, they them- 
selves have six or none ; while their species possesses a 
complex brain, they are brainless, or have imperfect brains ; 
while their species is known by its cloven hoofs, they have 
solid hoofs, and so on.* Dissemblances as great are ob- 
servable in moral characteristics. We see animals of ordinary 
aptitudes engender offspring sometimes remarkable for their 
fine qualities, and sometimes for their imbecility. The savage 
wolf brings forth occasionally a docile amiable cub ; the man 
of genius owns a blockhead for his son. In the same family 
we observe striking differences in stature, aspect, and disposi- 
tion. Brothers brought up together in the same nursery, 
and under the same tutor, will differ as much from each 
other as they differ from the first person they meet. From 
Cain and Abel down to the brothers Bonaparte, the striking 
opposition of characters in families has been a theme for 
rhetoric. Nor is this all. In cases where the consanguinity 
may be said to be so much nearer than that of ordinary bro- 
* “ Flaclisland rapporte que deux epoux bien constitutes mirent au inonde 
trois enfans sans avant-bras ni jambes ; d’autres dont parlc Schmucker 
n’eurent que des enfans munis de douze orteils et douze doigts.” (Burdach, 
c Traite de Physiologic,’ ii, 264. 
