88 THE PHYSIOLOGY OF THE COMMON CRAYFISH. 
do we mean by ‘being aware” and “knowing”? 
Certainly it cannot be meant that the crayfish says to 
himself, as we do, ‘‘ This is dangerous,” ‘‘ That is nice ;” 
for the crayfish, being devoid of language, has nothing to 
say either to himself or any one else. And if the cray- 
fish has not language enough to construct a proposition, 
itis obviously out of the question that his actions should 
be guided by a logical reasoning process, such as that 
by which a man would justify similar actions. The 
crayfish assuredly does not first frame the syllogism, 
“‘Dangerous things are to-be avoided; that hand is 
dangerous ; therefore it is to be avoided; ” and then act 
upon the conclusion thus logically drawn. 
But it may be said that children, before they acquire 
the use of language, and we ourselves, long after we are 
familiar with conscious reasoning, perform a great variety 
of perfectly rational acts unconsciously. A child grasps 
at a sweetmeat, or cowers before a threatening gesture, 
before it can speak ; and any one of us would start back 
from a chasm opening at our feet, or stoop to pick up a 
jewel from the ground, “ without thinking about it.” 
And, no doubt, if the crayfish has any mind at all, his 
mental operations must more or less resemble those which 
the human mind performs without giving them a spoken 
or unspoken verbal embodiment. 
If we analyse these, we shall find that, in many cases, 
distinctly felt sensations are followed by a distinct desire 
to perform some act, which act is accordingly performed ; 
