520 WHITE BLOOD-CORPUSCLES. [SECT. 221. 



the number of the blood-globules, we may venture to draw some 

 general conclusions from Avhat we know of the amount of solid 

 constituents in them : that they are present in larger quantity 

 in the male than in the female sex ; further, that after repeated 

 venesections, and after prolonged abstinence, they decrease in 

 number ; and that in certain diseases, as chlorosis and ansemia, 

 they are much more scanty than usual. — The blood-globules, com- 

 pared with the other constituents of the blood, are heavier than 

 the serum and the plasma. In the serum, and in the defibrinated 

 blood, they form a red sediment on standing, while in the plasma 

 they do not generally sink below the surface of the fluid, on 

 account of its quick coagulation. This sinking of the blood-cells, 

 which takes place more slowly or more quickly, according to their 

 own density and to that of the fluid in which they are suspended, 

 may be promoted by their mutual cohesion, which is especially 

 observable in inflammatory blood : here, owing to the quick pre- 

 cipitation of the blood-cells, a part of the blood coagulates colour- 

 less ; but the same phenomenon also occurs in quite healthy blood, 

 and, indeed, may be observed very constantly in the small drops 

 which come from slight cuts of the skin, and frequently also in 

 the blood of venesection. In such cases, the blood -globules are 

 applied to each other by their flat surfaces, and form, as it were, 

 little columns or rouleaux, at the side of which other similar 

 rouleaux may be applied, so that very complicated branched 

 figures may result, or even a system of networks covering the 

 whole field of the microscope (fig. 211, c). 



Besides the coloured elements, a certain number of uncoloured 

 particles occur in the blood. These are of tw r o kinds : elementary 

 granules of a fatty nature, and real cells. The former, which 

 completely agree with the fat granules of the chyle (see § 220), 

 occur to a very variable extent, sometimes being entirely absent 

 or in very small numbers, sometimes in larger, or, it may be, in 

 enormous amount, so that they communicate to the serum a 

 whitish or even milk-white colour. From all that we know, these 

 must be present every time fat is introduced into the blood by the 

 chyle ; and, therefore, even in ordinary alimentation they must 

 enter the circulation in three to six hours, or longer, after the 

 taking of food ; yet, in many cases, they seem to disappear in the 

 pulmonary circulation ; at any rate Nasse (see Wagner's Handw. 

 i., p. 126) and others, have never observed them in the systemic 

 blood of healthy people, and this is a statement which I can con- 

 firm as regards my own blood. On the other hand, in herbivora 



