THE NUMBER OF BLOOD-CELLS. 229 



differences which take place in the blood-corpuscles of the spleen, 

 the venous blood of this organ is found to differ from the arterial, 

 not only qualitatively, but also quantitatively, in reference to the 

 blood-cells. We learn from the investigations of Mayen, Hering, 

 and Nasse, that the arterial blood contains fewer blood-corpuscles 

 than the venous. Schmid found a much smaller number in the portal 

 blood than in that of the jugular veins ; I found a much larger 

 quantity in the blood of the hepatic veins than in that of the 

 portal vein, and even more than in that of the jugular veins, the 

 vena cava, and the splenic vein. 



In the blood of the hepatic veins of a horse which had been fed 

 four hours before death, I found 743 p.m. of moist blood-cells, 

 whilst there were only 592 in the blood of the external jugular 

 vein of the same animal, only 664 in that of the vena cava, 573 

 in that of the portal vein, and only 322 in that of the splenic 

 vein. 



My own experiments, as well as analogous physiological obser- 

 vations, concur in showing that scanty nutrition and prolonged 

 abstinence from all food diminish the number of the blood- 

 corpuscles. 



From what has been already said in reference to the func- 

 tion of the liver (see page 101), and the influence of fat on the 

 formation of cells (vol. i. page 266), we need not wonder that 

 Popp should have found an augmentation of the number of the 

 blood-corpuscles, and more especially of the colourless ones, after 

 the prolonged use of cod-liver oil. 



We should naturally expect that repeated venesections would 

 occasion a diminution in the number of blood- corpuscles ; and 

 Andral and Gavarret, Simon, Becquerel and Rodier, Zimmermann, 

 Popp and Nasse, have shown by direct experiments that this is 

 the case. Although the correctness of these views has been 

 proved by all the inquiries instituted on the subject, no average 

 proportion has as yet been established between the diminution of 

 the blood-corpuscles and the quantity of the blood abstracted, or 

 the number of times venesection has been performed. 



We cannot hope to discover a definite proportion between the 

 decrease of the blood-cells and the abstraction of blood, until we 

 can accurately determine the individual magnitudes of all the 

 coincident momenta. It is not difficult to perceive, that for the 

 present, no such determination can be arrived at ; for the inter- 

 cellular fluid will in one case (as for instance, from deficient nutri- 

 tion in already depressed and reduced organisms) be less rapidly 



