i)V QUADRUPEDS. 
295 
Seeing, then, that the size of the brain in comparison with 
that of the body could not be taken as the test of intellectual en¬ 
dowments, Soemmerring proposed, between man and other ani¬ 
mals, a criterion which he considers to be much less deceptive 
than a comparison of the body with the brain; namely, that of the 
brain with its own nerves. His theory is, that, as far as mere 
animal existence is concerned, a small portion of the brain is suffi¬ 
cient to influence the nerves, and that, therefore, the surplus 
quantity beyond this small portion (a portion not determined) will 
be available for the purposes of intellectual operations; so that 
where the greatest surplus exists, there the highest intellectual 
capacity will be enjoyed. Man, for instance, whose bodily powers 
are only moderate, has the largest brain in proportion to the nerves, 
and to the demand made upon their agency as regards mere ani¬ 
mal life. After man come the simise, as a further illustration of 
his position, to which he says he was conducted by a most careful 
and accurate comparison of a great number of brains ; he remarks, 
that the largest horse’s brain in his possession weighed one pound 
seven ounces, and the smallest adult’s brain he ever met with ex¬ 
ceeded this weight by fourteen ounces and a quarter; yet the 
nerves on the base of the former w^ere of ten times greater magni¬ 
tude than were those on the base of the latter. ‘ It must not, 
however, be concluded,’ he observes, ‘ that man has smaller nerves 
than any other animal. In order that my ideas may be better 
understood, I shall state the following hj’pothetical case :—Suppose 
the ball of the eye to require six hundred nervous fibrils in one 
instance, and three hundred in another, though only half the size 
of the former; and farther, that the eye with six hundred fibrils 
possesses a brain of seven, and that with three hundred of only 
five drachms; to the latter we ought to ascribe the largest brain, 
and a more ample capacity of registering the impressions made on 
the organs of vision; for, allowing one drachm of brain to each 
hundred fibrils, the brain which is absolutely the least, will have a 
superfluous quantity of two drachms, while the larger has only 
one.’ That the eye which is supplied with a double quantity of 
fibrils may be a more complete organ of sense, may be readily ad¬ 
mitted ; but the remark is inapplicable to the point in question.” 
The author then proceeds to confute the statement of Soem¬ 
merring. He allows that man possesses a larger brain than any 
other animal, compared with its nerves, but denies that nerves of 
the same magnitude do require the same proportion of brain for 
the exercise of their respective functions; or that the same nerve 
in different animals demands an equal quantity ; or, farther, that 
the proportion of brain required by a large nerve is greater than 
that required by one of inferior size; and moreover, to say, that 
