( 103 ) 



After this, I took the Brain of an Ox immediately after the head 

 was cut off, and forthwith proceeded to examine the corticle of the 

 Brain with all the care and attention I was able. In feveral exa- 

 minations of which, I thought I v^as allured that the vitreous and 

 very pellucid fubflance (which conftitutes the greateil; part of the 

 corticle), coniifted of nothing elfe than of exceffively flender ftreaks 

 or veffels clofely joined together; though at another time, I could 

 not fatisfy myfelf fo fully in that refpe(ft as I wiflied to have done. 

 With regard to the component parts of the corticle, I could not dif- 

 cern any difference from what I have before related of the 

 other fubjedls I examined, except that I did not here perceive lb 

 much fluid matter, as where the animals had been killed fome time. 

 The white, or medullary fubftance of the brain, I found to be of 

 the fame nature as I have defcribed in a Sheep. For, when I ob- 

 ferved the very white lines or ffreaks in the medullary part (from 

 whence the fpinal marrow takes its origin), I found the reafon of 

 its great whitenefs, to be a number of very tranfparent veffels ad- 

 joing to each other, which feemed to me,, formed for conveying 

 from the fubftance to noiu'iili and fupport the Ijjinal marrow, and in 

 part the nerves : the largell of thefe veffels dellined for conveying 

 fuch nourilhment, feemed to me, as nearly as I could judge by mv 

 eye, to be about the hundredth part of the thicknefs of a hair of 

 my beard, though at another time, I faw them much larger ; but 

 in this inllance, I think I happened on that part of the Brain where 

 thole tranfparent v-ellels v/ere the fmallell of all. 



In all thefe my obfervations, it mull be underllood, that I take 

 no notice of the multitudes of blood veffels difperfed throughout the 

 ]>rain, which, upon diffecling it, may be feen with the naked eye. 

 For tilefe are, as it were, entire rivers, when compared with the 

 fmall vellels I difcovered, and have been now defcribiiig, whicii 

 may be deemed as the fmallell brooks, channels, and ditches. 



I alio examined the corticle of the Brain in Sparrows, immedi- 

 ately after having killed them. In thefe, I not only obferved with. 



