C 105 ) 



fide by fide, would not equal -1-th part of the axis 



^2^640 °^ ^^^ S'^^^'^ °^ ^^"*^' ^^ follows that the axis of 

 fuch a grain is 2,040 times larger than the breadth 



105,600 of one of thofe fmall veffels. This number 2,04o 



,584,0 ' 



5,280 



' ' being multiplied into itfelf, to find the folid con- 



tents of a body whofe axis is 2,640, the refult is 

 ' ' more than eighteen thoufand millions : fo that 



2,640 1 • /~ 



a large gram of fand, as before-mentioned, must 



278,784,000 ][jg divided into fo many millions of parts before 



4,181,760,0 r ^u /- .. i- ■ . \i 



13 939 "00 ^^y °^^ tnele parts can pats into the cavity 



of thofe minute veflels. And the minute vellels, 



' ' ' which in part conftitute the vitreous fubftance of the 

 Brain, I take to be fo fmall, tliat no particle or 

 grain of large fand could pafs through them, unlets it were firft 

 divided into many millions of parts. > "-^l 



With regard to the Brain of a Sparrow, I found, by many ob- 

 fervations, that thofe parts which are called the medullary fubllance 

 do, for the moft part, confift of wonderfully minute fibres or vef- 

 fels : and in this part I met with as many fmall blood-velfels as I 

 have before mentioned to have feen in the corticle. The remainder 

 of the white fubllance in the Sparrow's Brain did not differ from 

 that in the Ox, Sheep, and Turkey, as I have before mentioned, 

 except that the tranfparent oily globules, which were enclofed by 

 fome of the veflels, were not fo large in the Ox. But in the Brain 

 of a Sparrow which had been killed twenty-four hours, I found 

 thofe oily globules, as far as my eye" could judge, to be of the fame 

 fize as in the brain of an Ox or other animal. From thefe laft ob- 

 fervations, and from my former ones, I began to confider whether 

 that great number of lucid globules (which may be confidered to 

 be of an oily fubllance) were not a fluid in the veflels, or perhaps 

 the veflTels themfelves, which, while the animal was living, con* 

 tinually conveyed a fubllance for the nutriment of the fpinal mar-i- 



voi.. n. , o 



