

THE BLOOD. 159 



bably, the source of the fibrine in the plasma ; both the latter and 

 the tissues assimilating it to themselves (p. 86). 



2. The Blood-corpuscles. 



The blood of the lowest animals consists of a fluid merely, the 

 analogue of the liquor sanguinis already described. As we ascend 

 in the scale, we first find colorless corpuscles added to this por- 

 tion ; and, in the vertebrate animals, still a third element, also, the 

 colored corpuscles. 



A. The Colorless Corpuscles of the Blood. 



The colorless corpuscles of the blood (lymph-corpuscles Figs. 

 95 and 96) are the cytoid corpuscles already described (p. 145) as 

 existing in lymph, chyle, and exuda- 

 tions. They are far less numerous 

 than colored corpuscles (1 to 346, or 

 even 400 in adults 1 ), are more globu- 

 lar, though not perfectly spherical, 

 and are not elastic. They average 

 33^3 of an inch in diameter. They 

 have a granular cell-membrane, or 

 capsule, and either a single round or colorless wood-corpuscies. (Magnified 400 

 reniform nucleus, or several small nu- 

 clei heaped upon each .other. They are lighter than the red cor- 

 puscles, since they contain a larger amount of fat, and are also de- 

 ficient in the iron contained in the latter. The capsule is so viscid, 

 that they possess a well-marked tendency to conglomerate into larger 

 or smaller groups. Hence, while circulating in the capillary vessels, 

 they are seen rolling slowly along upon the internal surface, while 

 the red corpuscles move rapidly on in the central portion of the 

 blood-column. Their quantitative analysis has not been attempted. 



The cell-membrane, or capsule, is probably an albuminous sub- 

 stance. 



The contents of the cytoid corpuscles consist of an albuminous 

 solution, containing extremely fine granules in suspension, most of 

 which are formed, doubtless, of fat. A distinct molecular motion 

 is produced in them by the endosmotic action of water. 



1 Moleschott finds the proportion in children 2 to 12 years old, as 1 to 226 ; at 

 22 years, 1 to 330 ; 30 to 50 years, 1 to 346 ; 60 to 80 years, 1 to 381 ; women when 

 menstruating, 1 to 247 ; not menstruating, 1 to 389 ; in pregnancy, 1 to 281. 



