330 



ther by ligament, and forming a tube communicating from one ex- 

 tremity of the spine to the other. 



This species of intervertebral joint, which thus appears common to 

 the fish tribe, is not found to obtain in the whales, as their structure 

 in this, as in many other respects, is the same as that of quadrupeds, 

 but is more distinctly visible, from the vast size of the parts. In them 

 the intervertebral substance is arranged in concentric circles, con- 

 nected by transverse fibres, the external layers being very firm and 

 compact ; but the interior become successively softer, till in the centre 

 there is a soft pliant substance, more like jelly than an organized 

 body, corresponding in its use to the incompressible fluid in fish. 



In the bullock, sheep, deer, monkey, and man, the structure cor- 

 responds with that of the whale ; but in the hog and rabbit a cavity 

 was observed, with a smooth internal surface extending through half 

 the diameter of the vertebrae ; so that the structure in these animals 

 imitates that of fishes, though not for any obvious purpose. 



In the alligator the several joints are regularly articulated with 

 capsular ligaments, and are lubricated with synovia. In the snake 

 there is a regular ball and socket joint between every two vertebrae ; 

 so that the means employed for the motion of the back-bone in dif- 

 ferent animals, comprehends almost every species of joint. 



Mr. Home's paper has annexed to it an appendix, by Mr. William 

 Brande, giving an account of the chemical analysis of the fluid con- 

 tained in the intervertebral cavity of the Squalus maximus. 



Its specific gravity was found to be '1027. It was not coagulated 

 by heat. 



No precipitation was occasioned by infusion of galls, or of catechu; 

 nor was any change produced by alcohol. 



But oxymuriate of mercury, muriate of tin, nitrate of silver, and 

 acetate of lead, threw down copious precipitates. 



From the effect of these re-agents, it appears to Mr. Brande, that 

 the fluid contains neither gelatine nor albumen ; but when the fluid 

 was evaporated to half its bulk, pellicles began to form on the sur- 

 face, indicating the presence of a variety of animal matter, which the 

 author considers as mucus or mucilage, but which, under certain cir- 

 cumstances of evaporation, is capable of being converted into a mo- 

 dification of gelatine or albumen. 



On Platina and native Palladium from Brazil. By William Hyde 

 Wollaston, M.D. Sec. R.S. Read March 22, 1809. [Phil. Trans. 

 1809,;?. 189.] 



Until a portion of platina was lately discovered by M. Vauquelin, 

 in some silver ores from Estremadura, the whole of the platina known 

 in Europe was derived from the Spanish possessions in South Ame- 

 rica, and had very uniformly the same appearance, differing solely in 

 the magnitude of the grains. 



A third variety having lately been received from Brazil, the author 



