PARTS OF THE ENCEPHALON. 237 



twenty-five ounces to as low as ten ounces, in a female, forty-two 

 years of age ; and eight and a half ounces in an idiot boy, twelve 

 years old ; this is the smallest idiot brain on record. The propor- 

 tionate weight of the brain to the body, in idiots, has been found as 

 low as 1 to 144. The weight of the brain varies in the races of man- 

 kind, chiefly, however, it would seem, in harmony with their stature ; 

 for the cubical capacity of the cranium, which is a fair indication of 

 the size of the brain, and in the European, on an average, measures 

 about 80 cubic inches, is, in the large-bodied negro, about 70 cubic 

 inches ; in the smaller Bush tribes, about 60 cubic inches ; and in the 

 Hindoos, also of diminutive stature, though of fine organization, it is 

 said to be as low as 47 cubic inches. 



The entire brain, or encephalon, is made up chiefly of two parts, 

 an anterior upper part, much larger, called the cerebrum or brain 

 proper, Fig. 12, a, and a smaller posterior and inferior part, called 

 the little brain or cerebellum, b. Besides these, there are certain con- 

 necting parts at the base, constituting the cerebral peduncles, the pans 

 Varolii, and the medulla oblongata. The cerebrum and cerebellum 

 are supported at their base, on certain stalk-like parts called pedun- 

 cles, from which a sort of main stalk, formed by the medulla oblongata, 

 is prolonged out of the cranium into the spinal canal, forming the spinal 

 cord. The' spinal cord, c, is a cylindrical mass of nervous substance, 

 which extends from the opening in the base of the skull, down to 

 about the lower part of the body of the first lumbar vertebra, where 

 it becomes pointed, c, and terminates in a slender membranous fila- 

 ment, which runs downwards, and is attached to the lower part of the 

 canal in the sacrum. The continuation of the spinal cord upwards 

 within the cranium, towards the peduncles of the cerebrum and cere- 

 bellum, is named the medulla oblongata, Fig. 60, m; it is of a pyra- 

 midal form, having its base turned upwards, and measures about one 

 inch and a quarter in length. Just above the medulla oblongata, in 

 front, is a broad transverse band of nervous substance, called, after 

 an old anatomist, the pons Varolii ; this extends laterally into the 

 cerebellum. Issuing from above the pons, are the stalks or peduncles 

 of the cerebrum ; these are continuous upwards with the cerebrum, 

 and downwards, through the pons, with the medulla oblongata and 

 cord. The cerebellum, Figs. 12 and 60, b, is also connected by 

 peduncles, with the back part of the cerebral peduncles, the pons and 

 the medulla ; thus its inferior peduncles attach it to the medulla, its 

 middle peduncles are formed by the lateral extensions of the pons, 

 and its superior peduncles join it to the back of the cerebral peduncles. 



Supposing the entire brain or encephalon to weigh fifty ounces, the 

 cerebrum would weigh about forty-four ounces, the cerebellum five 

 ounces, the pons and medulla oblongata one ounce. The propor- 

 tion between the cerebellum and the cerebrum is therefore about 1 to 

 8.8. In early life, the cerebellum is much less 1 developed in propor- 

 tion to the cerebrum, the ratio between the two being then as 1 to 13 

 or 15. The cerebellum acquires its maximum weight between twenty- 

 five and forty years of age ; its rate of increase, after fourteen, is pro- 

 portionately greater in the female. In idiots' brains, owing to the 



