| measure of intelligence in an animal. 
906 
stance, there is always found, in the cerebellum, 
a third intermediate yellow substance. All the 
medulla of the cerebellum is also united in the 
middle by a thick cord. Experience teaches 
that, in the structure of the brain, irregularities 
are far more uncommon than in other parts of 
the human body. It is worthy of observation, 
that every part of the brain is exactly symmetri- 
cal with the part opposite. Hven those which 
lie in the middle, and are apparently single (the 
spinal marrow, for instance) consist, in fact, of 
two symmetrical portions. 
The total weight of the human brain is esti- 
mated at two or three pounds. It is larger and 
heavier in proportion to the youth of the subject; 
and in old age it becomes specifically lighter. In 
delirious affections, it is sometimes harder and 
sometimes less solid and softer. 
The proportion which the size of the brain 
bears to that of the entire body, varies greatly 
for different mammalia. Hven in the same in- 
dividual it will change with the degree of fat- 
ness, or with the age of the animal. As these 
circumstances cannot be supposed to affect the 
powers of the mind very materially, we may na- 
turaily inquire how the relative size of the brain, 
and of the entire body, can be assumed as the 
To enable 
the student to form his own conclusions on this 
subject, we annex the following table, showing 
the proportion that the size of the whole body 
bears to that of the brain in several animals :— 
The Squirrel monkey (Callithriz sciureus) as 22 to 1 
Capuchin monkey (Cebus eS Saye 
Striated monkey (Jacchus vulgaris) ... 28... 1 
Field mouse (Arvicola vulgaris) rol aa 
| Man, according as he is 
young or old as 22, 25, 30 and 36... 1 
| The Mole (Talpa Europea) as 35... 1 
| Coaita monkey (Ateles paniscus) . ... 41... 1 
Mouse (Mus musculus) 43... 1 
Varied monkey (Cercopithecus mona) .. -44...1 
Gibbon (Hylobates lar) ; 48 ... 1 
Collared Mangabey monkey 
(Cercopithecus Aithiops) . 50 GIS) lace! 
Rat (Mus decumanus) . co LOheee ol 
Ruffed Lemur (Lemur Macaco) . 84... 1 
Porpoise (Delphinus phocena) 50 BB cos I 
Great bat (Vespertilio Noctula) 5 OB cao Il 
Dolphin (Deiphinus 
delphis) as 25, 36, 66, and 102... 1 
Cia baboon (Papio Maimon) as 104... 1 
Barbary ape (dnuus magotus) -- 105... 1 
Ferret (Mustela furo) . SEARS loko ream | 
Rabbit (Lepus cuniculus) as 140, and 152... 1 
Cat (Felis catus) as 82, 94, and 156... 1 
Hedgehog (Erinaceus Burepeeus) as 168 ... 1 
Fox (Canis vulpes) 5 FAVS) cag I 
Calf (Bos taurus junior) Boo Pall) Gao 
Hare (Lepus timidus) 556 PPAS} So Il 
Wolf (Canis lupus) .. 230... 1 
Panther (Felis pardus) So OFT ode! 
_ Ass (Equus asinus) -- 254... 1 
Bear (Ursus arctos) . : 3 B80 740%). Goo I 
Beaver (Castor fiber) 290 ... 1 
Sheep (Ovis ariés) as 192, and 351 ... 1 
Marten ( Viverra martes) as 365 ... 1 
Dog (Canis familiaris) 
as 47, 50, 57, 154, 161 and 365... 1 
BRAIN. 
Horse (Equus caballus) as 400 to 1 
Domestic hog (Sus scropha) Ue o5 1 
Elephant (Elephas Indicus) . 000... 1 
Wild boar. (Sus scropha) 672... 1 
Ox (Bos taurus) : 860 ... 1 
From the above table it would appear that the 
brain is proportionably largest in the smaller ani- 
mals. Man is surpassed in this respect only by 
a small number of mammalia, and these are lean 
and meagre. ‘The rodentia generally possess the 
largest proportional brain, and the pachydermata 
the smallest. It is very difficult, if not impos- 
sible, to arrive at these results with any great 
degree of accuracy, because the weight of the 
brain generally remains the same, while that of 
the body will vary considerably according as an 
animal is lean or fat. 
The proportion which the cerebrum bears to 
the cerebellum is, in 
The Squirrel monkey (Cali 
sciureus) 3 as 14 to 
Man : 568 : 
The ox (Bos taurus) : 
Dog (Canis familiaris) 
Wild boar (Sus scropha) . 
Horse (quus caballus) 
Cat (Felis catus) 
Hare (Lepus timidus) 
Sheep (Ovis aries) 
1 
1 
] 
1 
Soul 
all 
] 
] 
1 
Mouse (Mus musculus) 1 
bo Or DANA D OC 
“It is @ common opinion,” observes Dr. Her- 
bert Mayo, “ that the front of the brain is the 
seat of the intellectual faculties ; yet in monkeys 
and in man the back part of the brain is that 
which has the largest relative size. The sheep, 
on the other hand, has an ample front to its 
brain, a large intellectual region, according to 
the phrenological theory, while its instinct of 
attachment to its young has a poor locality in 
its moderate posterior cerebral lobe. Has no- 
thing then been discovered to mark an essential 
superiority in the brain of man? ‘The question 
must, I believe, be answered in the negative. No 
physical condition, distinguishing the human 
brain from that of animals, and therefore fitting 
it to co-operate with a rational soul, has as yet 
been ascertained, or even plausibly conjectured 
to exist.” Physiologists have been led, in all 
ages, by that marked superiority of mental power 
which man possesses above the other animals, to 
seek in the structure of their brains for some 
corresponding difference. It was long supposed 
that man has the largest brain in comparison to 
his body; but the above tables show that he is 
surpassed by several quadrumana, and by the 
mouse. 
There is another point of comparison which 
seems to approach nearer to their actual com- 
parative intelligence, which was first proposed 
by Sommering. By comparing the quantity of 
the brain with that of the nerves arising from it, 
we ascertain more accurately the degree in which 
its purer intelligence excels its mere animal na- 
ture. “ Let us divide the brain into two parts ; 
= 
Neen a  reee eee eneeeel 
