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^ the axis of a globule of blood to be as -1 ; the rcfult is, that if 

 4 a grain of fand \i;as divided into fixty-four niiUions of parts, not 

 T- one of thofe parts could enter the orilices of the fmallctl vef- 

 •1- lels in the Erain, and efpocially, if the fmall particles of the 

 ~ blood were not llexible ; but T think that the fniall particles 

 — of the blood arc equally tlexible with thofe globules \Nhich are 

 of full fize. I alfo found the corticlc of the Brain in the Sheep to 

 confift of a clear vitreous fubftancc, tlie fame as I have deferibed in 

 the Brain of a Turkey ; with this only difference, that I faw in this 

 fome thin white fireaks, which could not ealily be difcovered by the 

 naked eye, fome thinner than a hair of one's head : thefe ftreaks 

 I judged to be caufed by a greater collciflion than ufual, of thofe 

 large tranfjiarent globules \s hich caufe the medullary parts to appear 

 \Ahite. I abb obferved in the medullary parts fome dark ftreaks of 

 the colour of the corticle, which dark llreaks, I judged proceeded 

 only from this, that there were few or none of thofe pellucid glo- 

 bules in that part. 



After this, I examined the white or medullary parts of the 

 Brain, and principally thofe which are the beginning of the fpinal 

 marrow ; and here I think I faw, fometimes very clearly, what 1 

 had not been able to diftinguifli in the Brains of Turkeys, namely, 

 that thofe large and tranflucid (as they appeared to the fight) oily 

 globules, were in a manner furrounded, or lay in the midft of, an 

 inexpreffible nvmiber of wonderfully minute veflels or ftreaks in the 

 form of net- work, mixed with fome larger ones, which were in a 

 ftraight direction and A'cry tranfpai-ent, caufing the Brain where 

 they were collefted in any quantity, to appear uncommonly white 

 to the eye : thefe, by feveral obfervations, appeared to me to be 

 about the twenty-fifth part the thicknefs of an hair, and to be of a 

 dark colour. The remainder of the medullary fubftancc confifted 

 of the fame kind of parts, as I have faid I obferved in the Brains 

 of Turkeys. And yet I fometimes had my doubts, whether all I 

 deemed to be veflels were fo in reality. 



