5S2 WEIGHT OF BRAIX AND CORD. 



compared -n-itli that of the medulla oblongata at its base or broadest part, is 

 about 7 to 1 , while in many quadrupeds it is as 3 to 1 or even as 2 to 1, 



WEIGHT OF THE SPINAL CORD. 



Divested of its membranes and nerves, the spinal cord in the human subject 

 weighs from 1 oz. to l| oz., and therefore its proportion to the encephalon is 

 about 1 to 33. Meckel states it as 1 to 40. 



The dispro^iortion between the brain and the spinal cord becomes less and less 

 in the descending scale of vertebrata. until at length, in cold-blooded animals, 

 the spinal cord becomes heavier than the brain. Thus, in the mouse, the weight 

 of the l^rain. in proportion to that of the spinal cord, is as 4 to 1 ; in the pigeon, 

 as 3?j to 1 : in the newt only as | to 1 : and in the lamprey, as ^^ to 1 . 



In comparison v.-ith the size of the body, the spinal cord in ma,n may be stated 

 in general terms to be much smaller than it is in animals. In regard to the 

 cold-blooded animals, to birds, and to small mammalia, this has been actually 

 demonstrated. but not in reference to the larger mammalia. 



R. Wagner states as follows, the proportion of the weight of the spinal maiTOW 

 taken as 1 to the encephalon and its pai-ts — 



(U to the nerve roots 



//. to the medulla and pons 



<■, to the cerebellum 



(I, to the cerebrum 



r, to the encephalon 



SPECIFIC GRAVITY OF THE ENCEPHALON. 



The specific gi-avity of the different parts of encephalon has of late at- 

 tracted some attention from its having been observed that it varies to some 

 extent in different kinds of disease. From the researches of Bucknill, Sankey, 

 Aitken. and Peacock, it appears that the average specific gravity of the whole 

 encephalon is about 1030, that of the gi'ey matter 1034, and that of the white 

 1040; There are also considerable differneces in the specific gravity of some 

 of the internal parts. (William Aitken, " The Science and Practice of Medicine," 

 18G5. vol. ii. p. 2i'u> : J. C. Bucknill. in " The Lancet."' 1852 : Sankey, in the 

 " Brit, and For. Med. Chir Review,"' 1853 : Thos. B. Peacock, in the Trans, of 

 the Pathol. Soc. of London. 18G1-2.) 



