Page:The Galaxy, Volume 6.djvu/53

1868.] 10 ounces and 5 grains. The subject, a female, though forty-two years of age, had an intellect which is described as "infantine." She could say a few words, such as "good," "child," "morning," with tolerable distinctness, but without connection or clear meaning, and was quite incapable of anything like conversation. Her habits were decent and cleanly; but she could not feed herself, at least, with any degree of method or precision. She was fond of carrying and nursing a doll. In a case described in a subsequent number of the same journal, by Professor Marshall, the weight of the entire brain was but 8 1-2 ounces. The subject was a boy twelve years of age. Nothing is said relative to the intelligence manifested.

Absolutely the normal human brain is larger than that of any other animal except that of the elephant and the whale. Relatively to the weight of the body it very greatly exceeds the proportion existing in either. Leuret found the mean proportional weight of the brain to the rest of the body, to be in fishes as 1 to 5,668. The range in these animals is, however, very great. In the bass as the average of 11 observations, the writer found it to be as 1 to 523; in the eel, 22 observations, as I to 1,429; and in the garfish, 9 observations, 1 to 8,915.

In reptiles of different orders, Leuret determined the average to be as 1 to 1,321. The writer found the proportion in frogs to be as 1 to 520; in lizards as 1 to 180; and in the rattlesnake as 1 to 1,825. The brain of an alligator over six feet in length, which the writer examined, weighed but a little over half an ounce.

Next in order come the birds, and here we find a very decided increase in the proportion. From many determinations made by Haller, Cuvier, Carus, and himself, Leuret gives the average as 1 to 212. In the tomtit he found it as 1 to 12; in the canary-bird as 1 to 14; in the pigeon as 1 to 91; in the duck as 1 to 241; in the chicken as 1 to 377; and in the goose as 1 to 3,600. These are very great differences, and, as Leuret remarks, bear no constant relation to the intelligence. It is worthy of notice that the brain is proportionately smaller in those birds which are domesticated, and which, therefore, have to make a less severe struggle for existence than the wild birds, and their bodies consequently are more encumbered with fat. From determinations made by the writer, it was ascertained that the brain of the canary-bird reared in the United States was in weight, compared to that of the body, as 1 to 10.5, and in the Arctic sparrow as 1 to 11. No observations on record show proportionally larger brains than these.

Among mammals we find a still greater increase in the weight of the brain as compared with that of the body. Leuret found it to range in the monkeys from 1 to 22, 24, and 25; in the dolphin it was as 1 to 36; in the cat as 1 to 94; in the rat as 1 to 130; in the fox as 1 to 205; in the dog as 1 to 305; in the sheep as 1 to 351; in the horse as 1 to 700; and in the ox as 1 to 750. The mean for the class of mammals, exclusive of man, was as 1 to 186. The observations of the writer accord very closely with those of Leuret. He found that in the prairie wolf the proportion between the brain and the body was as 1 to 220; in the wild-cat as 1 to 158; and in the rat as 1 to 132.

Now although there is no definite relation existing between the intelligence and the size of the brain in individual animals of any one class, yet when we compare the different classes with each other, we find the connection very well marked. Thus, taking the data collected by Leuret, it appears that in fishes the brain is but one 5,668th part of the body; in reptiles it is one 1,321st part; in