Philosophical Tiansadions. 127 



of that species, but succeeded only in obtaining a male ; he 

 therefore tried to breed from the male quagga and a chestnut 

 mare, and the result was a female hybrid of decidedly mixed 

 origin ; vhe mare was afterwards bred from by a black Arabian 

 horse, and this latter produce exhibits in colour and mane a 

 striking resemblance to the quagga. It is curious enough that 

 features not belonging to the dam should be communicated 

 through her to the progeny of another male. 



Mr. Giles says, " I will now give the best account I can of 

 my sow and her produce." She was of Mr. Western's black and 

 white breed. Ten years ago she was bred from by a boar of 

 the wild breed, of a deep chestnut colour ; the pigs, (her first 

 litter,) were duly mixed, the colour of the boar being in some 

 of them very predominant. The sow was afterwards twice bred 

 from by Mr. Western's boars, and in both instances chestnut 

 marks were prevalent in the litter, which in other instances 

 had never presented any appearance of the kind. 



V. Tlie Croonian Lecture. Microscwpical Observations on the 

 folloiving Subjects : On the Brain a7id Nerves ; showing that the 

 Materials of ivhich they are composed exist in the Blood. On 

 tlie Discovery of Valves in the Branches of the Vas Breve, 

 lying bettveen the villous and muscular Coats of the Stomach. 

 On the Structure of the Spleen. By Sir Everard Home, 

 Bart. V. P. R. S. 



This lecture will be read with much interest by those who 

 are bold enough to fathom the depths of modern physiology, 

 and who put that confidence in Mr. Bauer's microscopical ob- 

 servations which we think they deserve. He examined the 

 optic nerve and found it to consist of many bundles of fine 

 fibres, formed of very minute globules united by a soluble trans- 

 parent jelly. " By the discovery of this transparent substance," 

 says Sir Everard, " we become acquainted with the nature of the 

 medullary structure of the nerves, and can form some idea of their 

 action, which till new I confess myself" to have been totally 

 imacquainted with. The nerves as well as the retina are com- 

 posed of this newly-discovered transparent substance which is 

 very elastic and soluljle in water, and globules of -gVu ^^^^ 

 ^oVo parts of an inch in diameter. Its transparency and solu- 

 bility account for its having remained concealed ; and were it 

 not coagulable, in which state it becomes opaque, its existence 

 might even now be considered as equivocal." The brain is 

 also, as Mr. Bauer's observations show, a conglomerate of 

 globules and soluble mucus, the former arranged into fibres and 

 bundles, held together by the latter. It is pervaded by blood- 

 vessels, but the arteries never anastomose, and the veins, which 

 are very small, are supplied with valves, and perform the 



