218 RED PARTICLES 



poise, which belongs to the same genus as the whale, that they 

 are smaller in those animals than in fish ; neither is their size 

 inversely as in the size of the animal, for they are as large in 

 an ox as in a mouse (xcvui). The difference in their size, 



(xcvm.) Among the mammalia, the harvest mouse, the smallest 

 British species, has corpuscles quite as large as those of the horse ; 

 and in the common mouse they are larger than in the ox or horse. 

 The corpuscles of the elephant are larger than those of any other 

 mammal ; the sloth has them next in size, and then comes the whale, 

 in which they are somewhat larger than in man, the capybara, and the 

 porpoise. The Napu musk-deer has the smallest corpuscles yet dis- 

 covered ; those of the Stanley musk-deer are about the same size ; 

 in the ibex (Capra Caucasica) they are rather larger, and in the goat 

 slightly larger still. The corpuscles of the goat were the smallest 

 known before my observations, referred to in Note cxvin*, p. 236. 



Although in mammals there is not much relation bet ween the size of 

 the corpuscles and that of the animal in different orders, there is such 

 a connexion in any one natural family. The corpuscles of the large 

 ruminants or rodents, for example, are larger than the corpuscles of 

 the smallest species. In the intermediate series there are several 

 slight exceptions, but no considerable one. Yet in different subdivisions 

 of one order the size of the corpuscles may differ so remarkably, that 

 the fact will probably be available as a help to classification. Thus the 

 ferae, if set down according to the size of their blood-corpuscles, would 

 stand as follows, seals, dogs, bears, weasels, cats, viverras ; and 

 one of the last may generally be distinguished, simply by the smaller 

 size of its corpuscles, from any species of the three first-named families. 

 Among genera of doubtful affinities, if regard were paid only to the size 

 of the blood-corpuscles, the hyaena would be arranged with the canidae, 

 basaris with the ursidae, and cercoleptes with the viverridae. The fox 

 has slightly smaller corpuscles than the dog. Though the smallest 

 corpuscles are found in the ruminants, some of the largest species of 

 this order have larger corpuscles than many carnivora, or than the 

 horse. The camel tribe are the only mammals with oval blood-discs, 

 like those of lower vertebrata in shape, but entirely agreeing in size and 

 structure* with the corpuscles of mammalia. The blood-corpuscles of 

 marsupial animals agree generally in form, size, and structure, with the 

 corpuscles of the corresponding placental animals. In the monotre- 

 mata, according to the observations of Dr. Davy, b Dr. Hobson and 

 Dr. Bedford, the corpuscles are similar, in all respects, to those of 

 man ; my measurements of the corpuscles of the echidna are to the 

 same effect. 



In birds and reptiles, with a few exceptions, the long diameter of the 

 oval blood-corpuscle is rather less than twice the short diameter. 

 These proportions used to be considered as universal; but the long 



a See Note en, pp. 222-3. c Tasmanian Journal, vol. i, p. 94, Van- 



b Proc. Royal Society, May 28, 1840. Diemen's Land, 1841. 



