REVIEW: — ILLUSTRATIONS OF INSTINCT. 
687 
that, by tracing the successive manifestations of the increasing fa- 
culties, we may understand the precise station which this faculty 
occupies in the ascending scale, and the means through which its 
operations are developed. We shall thus be taught that it is not 
so much an insulated faculty, of which the tissues and organs are 
no more than instruments, as an accumulation of powers combined 
together, and occupying a step in the course of a transition from 
the lowest to a higher condition of natural rank ; so that, its varia- 
tion or degree is due to the modification of these inferior powers 
which together form its constituent parts.” 
In accordance with this plan of procedure, our author commences 
his synthetic examination into the nature of instinct by men- 
tioning some of those endosmodic beings whose simple and sole 
design appears to be, 
“ to draw nutrition, propagate, and rot 
and then, taking one step up, passes on to a class in possession of 
organic sensibility or irritability, but still without instinctive feel- 
ings ; “ although it may happen that sympathetic and reflex motions 
may put on the appearance of something that resembles them.” 
“ There are no living beings in which this faculty of irritability 
or excitability exists alone; but there are families in which no 
other addition besides this is made to the principle that first came 
under our consideration. Creatures thus constituted possess the 
power of making selections of food, and of varying their functions 
according to extraneous circumstances or internal changes ; but it 
is only among the highest of these natural classes that any one 
can be said to display a preference. And in some even of these 
it is still simply through the influence of a reaction (such as by 
Dr. Marshall Hall has been termed a reflex action of the nerves) 
that any thing bearing resemblance to a bias of the will can be 
discerned.” 
“ The next stage of our inquiry will bring us to a still higher 
class; where we shall find not only the existence of wants, but 
consciousness of such a deficiency as the idea of a want implies : 
from which we shall be able to discern a rising impulse prompting 
to the search for a supply, as well to satisfy the craving of desire, 
as to palliate the pain of deficiency, or defend against danger. It 
is in this condition that an approach is made to the border of that 
which is properly understood by the term Instinct; and here, there- 
fore, we shall do well to pause, and consider the complication of 
circumstances included in that function or character.” 
“ The most complicated and most highly endowed of crea- 
tures are only constituted such by the addition of new tissues, or 
the modifications of those already existing, with their attending 
