703 SPECIAL HISTOLOGY. 



doubted, that in every individual the number of blood-cells is subject to 

 numerous, even daily changes, according to the conditions of supply and 

 waste, with Avhich we have still to be made accurately acquainted. The 

 volume of the blood-cells is estimated by Harting, regarding them as 

 short cylinders, as that of a cell of 0*0763 cubic millimeters; and the 

 iveAght, taking their specific gravity as equal to that of water, and ab- 

 stracting their central depression, at 1-13,114,000 milligramme. If, with 

 Schmidt, the blood is taken to contain 50 per cent, of corpuscles, and 

 the whole quantity of blood be estimated at 10 kilogrammes, we have a 

 total of 65 billions 570,000 millions. According to Schmidt, the spe- 

 cific gravity of the blood-corpuscles in men, is 1*0885-1'0889, and in 

 women 1*0880-1 '0886 — numbers wdiich must stand and fall with his 

 statements respecting the quantity of blood-corpuscles. Compared with 

 the other constituents of the blood, the corpuscles are heavier than the 

 serum and the ijJasma. In the former, and in defibrinated blood, they 

 form, upon standing, a red sediment, whilst in the plasma, owing to its 

 rapid coagulation, they do not usually subside below the level of the 

 fluid. This subsidence of the blood-cells, which, according to their own 

 density and that of the fluid in which they are suspended, may be slow 

 or rapid, is favored by their mutual cohesion, wdiich is observed especially 

 in inflammatory blood, in wdiich, from the rapid subsidence of the blood- 

 cells, part of the blood coagulates into a colorless mass ; but it also takes 

 place in perfectly healthy blood, and, in fact, constantly in little drops 

 obtained by trifling injuries of the skin, and frequently also in the blood 

 taken by venesection. The blood-globules in these instances apply 

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

 columns or rouleaux, to the sides of which others may be again applied, 

 so that very complicated branched figures, and even networks are in this 

 way produced, covering the entire field of view (Fig. 291, c). 



Besides the colored, the blood also contains a certain number of 

 colorless elements, of two kinds — elementary granules of a fatty nature, 

 and true cells. The former, which correspond entirely with those of the 

 chyle {vide § 221), occur in very varying number, sometimes very scantily 

 or not at all, sometimes in greater or even in vast numbers, so as to 

 give the serum a whitish or even milk-white color. From all that we 

 know, these must exist Avhen fat is introduced into the blood through 

 the chyle ; thus also in common alimentation, 3-6 hours and longer 

 after the taking of food, although in many cases they seem to disap- 

 pear in the course of the pulmonary circulation ; at all events Nasse 

 {vide Nasse, " Wagn. Handw. d. Phys.," I., p. 126) and others have 

 never found them in the systemic blood of healthy persons, a fact which 

 I can confirm as regards my own blood. In herbivorous Animals, on 

 the contrary, in the Goose, and in sucking Animals, the occurrence of 

 these molecules appears to be constant ; in pregnant women, also, and 

 after the free use of milk or alcoholic drinks, and also in famishing 



