94 



Whale. The Napu Mušk Deer has the most minute corpuscles ; 

 those of the Stanley Mušk Deer are nearly as small ; those of the 

 Ihex of Candia are larger ; and the next increase of size is in those 

 of the Goat. Before my obsei'vations, the corpuscles of the last- 

 named animal were the smallest known. 



Size ofthe corpuscles in relation to that ofthe animal. — The smallest 

 British mammal, the Harvest Mouse, has corpuscles quite as large 

 as those of the Horse ; in the Common Mouse they are larger than in 

 the Horse or Ox. But although there is no relation between the 

 size of the corpuscle and that of the animal in different orders, in the 

 šame order the larger species have generally larger corpuscles than 

 the smallest species. Thus, in the large Ruminants the corpuscles 

 are distinctly larger than in the smallest Ruminants, and the šame 

 fact is observahle of the Rodents. In these examples the gradation 

 in the size of the corpuscles may not exactly follow that of the ani- 

 mals, but none of the very small species have corpuscles so large as 

 those of the largest species. 



Size of the corpuscles in the šame animal at different periods of life. 

 — In very young embryos the corpuscles are much larger than in the 

 adult, and in such embryos each corpuscle has a nucleus, which dis- 

 appears at a later period of intra-uterine life, -vvhen the corpuscles 

 are yet larger than those of the mother. At a still later period they 

 become so uneąual in size that it is difiicult to say whether they be 

 larger or smaller in the foetus than in the adult. In a kid twelve 

 days old, bred betvveen an ibex and a goat, I found the corpuscles 

 larger and more variously sized than those of either of its parents. 



The thickness of the corpuscles is variable ; but it is commonly 

 somewhat more than a fourth of the diameter. 



Size of the corpuscles in different Orders. — The Monkeys have cor- 

 puscles pretty uniform in size, generally just perceptibly smaller 

 than those of Man ; in some of the Monkeys of the new world the 

 corpuscles are slightljf smaller than in the Monkeys of the old world, 

 and in the Lemurs somewhat smaller still. In the corpuscles of the 

 different subdivisions of the Feree there is such a \vell-marked diver- 

 sity of size, that the fact* might be used as a help to classification. 

 The families, set do\vn in the order of the size of their blood-discs, 

 stand as follows : Seals, Dogs, Bears, Weasels, Cats, Viverras. It 

 is commonly most easy to distinguisli a viverra, by the comparatively 

 small size of its blood-corpuscles, from a seal, dog or bear. Among 

 genera of doubtful afhnities, if regard vi^ere paid to the blood- 

 corpuscles, the Hysenaf \vould be arranged with the Canida, Basaris 

 with the Ursidcc, and Cercoleptes with the Viverrida. It is curious 

 that the Fox has slightly smaller corpuscles than the Dog. In the 



* It has recently been enlisted into the service of natūrai history by Mr. Jesse, 

 in his interesting AnecJotes of Dogs. 



t It is reuiarkable that the cxtent of the streaked muscular fibra of the gullet 

 of the Hyffina is the šame as in the Viverrida, which difFer in this respect from 

 the Canidie, and still more from the UrsidcB. See Proc. Zool. Soc., Sept. 10, 1839, 

 and June 11, 1842. It would be interesting to esamine the cesophageal muscular 

 sheath of the Kinkajou. 



