278 PHILOSOPHY OF ZOOLOGY. 
By degrees, they are directed to express the wants or the 
enjoyments of the other active powers. In all the indi- 
viduals of a species, the same sounds are uttered in expres- 
sing the same feelings. But among individuals belonging 
to different species, the greatest diversity prevails in the 
sounds of their natural language, as may be observed in 
the dissimilar cries of the lamb, the foal, and the calf. 
In many cases, this language appears exclusively to be 
a bond cf union between the young animals and. their pa- 
rents, by which the former. can express their wants, and 
guide the motions of the latter in supplying them. In 
proof of the truth of this remark, we need only observe, 
that this language of infancy is gradually neglected, as the 
protection of the parent ceases to be necessary ; and other 
sounds are employed, in the independence of maturity, to 
express the same feelings, and others belonging to their 
new condition. Thus, the cries of ducklings, when under 
the guidance of their mother, are-different from those which 
they utter when able to provide for themselves ; and when 
roaming about in the corn-yard, or swimming on the pond. 
That these established sounds, are equally natural with 
those uttered in infancy, is demonstrated by this cireum- 
stance, that ducklings hatched under a hen, and brought 
up remote from any other individuals of their own species, 
utter the sounds common to their kind. 
Some animals are destitute of any language at birth, 
and do not utter sounds until they have arrived at maturi- 
ty. In those cases, which occur among oviparous animals, 
there is no connection between the parent and the offspring, 
the latter having no wants but those which its own instincts 
can supply. Sounds, therefore, or cries, would be uttered in 
vain. But in approaching maturity, when it is necessary 
that an interchange of feeling should take place with others 
of its kind, a language is provided suited to the occasion. 
