The Blood Corpuscles

Corpuscles are contained in the blood of all Vertebrata. In Amphioxus they are all of one kind, colorless and nucleated. The genus Leptocephalus, among the Teleostei, is said to possess the same peculiarity; but, in all other known Vertebrata, the blood contains corpus cles of two kinds.

In Ichthyopsida and Sauropsida, both kinds are nucleated; but one set are colorless, and exhibit amaeboid movements, while the others are red, and do not display contractility. Except in the Marsipobranchii, which have round blood - corpuscles, the red corpuscles are oval. They attain a larger size in the perennibranchiate Amphibia than in any other Vertebrates.

In Mammalia, the blood - corpuscles are also of two kinds, colorless and red, the colorless possessing, and the red being devoid of nuclei. It is but very rarely that a nucleated corpuscle, with a red color especially developed about the nucleus, is seen in Mammalian blood; but such cases do occur; and, from this and other circumstances, it is probable that the Mammalian red corpuscle is a free - colored nucleus.

The colorless corpuscles of Mammalia are spheroidal, and exhibit amaeboid movements; the red corpuscles are flattened, usually circular, but sometimes oval (Camelidae) disks, devoid of contractility.