CORrUSCLES. 23 



Pale, white or colourless Corpuscles (figs, 10 and 13). — These 

 are comparatively few in number, of a rounded and slightly flattened 

 figure, rather larger in man and mammalia 

 than the red disks, and varpng much less than Fig- 13. 



the latter in size and aspect in different animals. 

 In man (during health) the proportion of the ^^ /5^ 



white corpuscles to the red is about 2 or 3 to ^ ^^ 



1000. This proportion is diminished by fasting r^ 



and increased after a meal, especially of albu- vf!/ 



minous food. Their number compared with the 



red corpuscles is said to be greater in venous Fig. 13. — Pale Coupus- 

 than arterial blood, and much greater jn the cles of Hcman Blood ; 

 blood of the splenic and hepatic veins than in magnified about 5uo 

 venous blood generally. They are destitute ^^iameters. 

 of colour and specifically lighter than the red Tlie upper two as seen 

 corpuscles. In nature \hey are in many re- ^° ^^'^ ordinary manner of 

 spects Bimilav to the embryonic cells already ^'STcii™ '.7S: 

 described (p. 8), and they possess m a high acetic acid, which brings 

 degree the capability of undergoing amosboid into view the single or 

 movement ; sending out processes (fig. 10, composite nucleus. 

 (/, 2)) into which their granules enter and re- 

 tracting them again, and even occasionally performing extensive 

 locomotion. The pale corpuscles possess one, two, or, commonly, three 

 nuclei, which are frequently obscured by the granular character' of the 

 protoplasm, but may be brought into view by dilute acids (fig. 13). Minute, 

 round, clear spaces may often be seen in the protoplasm (fig. 10) ; 

 they are entirely free from granules, although probably filled with 

 fluid, and have been named vacuoh's. They are also met vnth in the 

 embryonic as well as in other proto])lasmic cells. The colourless blood- 

 corpuscles are commonly distinguished into two kinds, according as 

 the protoplasm composing them is finely granular throughout "(fig. 

 10, J"?), or contains a greater or less number of coarser granules, 

 strongly refracting the light (//). "VMiether in the latter case the 

 granules have been formed from fluid matter within the corpuscle, 

 or whether they have not rather been taken in from the surround- 

 ing fluid, by the same process as an amceba takes in its food, is at 

 present uncertain : it is however an interesting fact that the pale 

 blood-corpuscles are peculiarly apt to take into their interior minute 

 solid particles that have been introduced into the blood ; this pro- 

 perty has served as a means of detecting escaped white corpuscles 

 in tissues which are wholly extravascular, the cornea for example 

 (Cohnheim). 



Albuminous granules, and molecules of a fatty nature occur in the 

 blood in varying numbers ; sometimes very scantily, or not at all, but 

 the latter sometimes very abundantly so as to give the serum a turbid, 

 milky appearance. These are probably derived directly from the chyle, 

 and they are especially seen in the blood of herbivora, in sucking 

 animals, and in pregnant women. 



Granular masses occasionally occur in drawn blood, even when 

 taken from a healthy person, but more especially in cachectic states of 

 the system, which on minute examination are seen to be composed of 

 excessively fine, colourless, discoid particles. The latter under favour- 

 able conditions develope into vibrating filaments which break away 



