196 



OF THE BLOOD ATTD CIKCULATIOff. 



puscles of the lower animals with those of man. In the mam- 

 malia they are in all essential -respects the same as in man, 

 round and discoidal ; for the most part, however, particularly 

 among the ruminants, decidedly smaller (fig. 209). In the 

 monkeys, again, they are very nearly of the same size.* In 

 birds, on the other hand, the blood-corpuscles are very differ- 

 ent, having an elongatedoval shape (fig. 210, A), and their broad 

 sides, instead of being depressed, are vaulted or raised (5). 

 They are on an average from 1-1 25th to 1-1 50th of a line in 

 length, and about half as broad. It is among the amphibia that 

 we meet with the largest blood-corpuscles. They are here, as 

 in birds, oval-shaped, but relatively somewhat broader ; and 

 their surface is rather depressed than vaulted. They are par- 

 ticularly large in the naked amphibia : in the Pro feus, for ex- 

 ample, they are from l-30th to l-50th of a line in the long 

 diameter, and are even distinguishable as little points by the 



Fig. 211. Blood-gl o^aies of the Proteus anguinus. In the glohule a* 

 the nucleus is seen, and m the glohule, d, which has heen treated with 

 water, it is still more apparent ; c is a lymph granule. 



* The blood-corpuscles of the monkeys are in no wise to he distin- 

 guished from those in man. In different human subjects, men, women, 

 children, negroes, no difference can be perceived. 



