IN VARIOUS PHYSIOLOGICAL CONDITIONS. 261 



does not coagulate, is because each individual drop forms a dis- 

 tinct coagulum, and that consequently the sum of the drops must 

 always constitute a tolerably fluid mass ; but when examined under 

 the microscope, menstrual blood does not exhibit any coagulated 

 substance near or among the corpuscles. On the other hand, 

 E. H. Weber found coagulated blood upon the mucous membrane 

 of the uterus of a young girl, who had killed herself during the 

 period of menstruation. 



.During digestion, the blood becomes richer in solid constituents, 

 this increase extending with tolerable uniformity to the blood-cells 

 and the plasma. The former gain in solid constituents, while they 

 experience a relative loss of hsematin (F. C. Schmid). The fibrin 

 of the intercellular fluid is scarcely perceptibly increased, but it 

 coagulates more slowly, and therefore more readily forms a crust 

 upon the clot. Lastly, it is richer in fat than the fibrin obtained 

 from the blood of fasting animals ; the serum is denser, sometimes 

 even exhibiting a milky turbidity from fat-globules and colourless 

 blood-cells. It also presents a tolerably uniform proportional 

 augmentation of fat, albumen, extractive substances, and salts. 



Prolonged fasting and extensive losses of blood or of the oilier juices 

 exert an action on the constitution of the blood precisely analogous 

 to that of those substances which interfere with digestion or resorp- 

 tion and the formation of blood ; as, for instance, many metallic 

 salts, and especially preparations of lead, acids, &c. In these con- 

 ditions, the number of the corpuscles diminishes in various degrees, 

 while the plasma becomes more watery, (that is to say, poorer in 

 albumen and other organic constituents,) but richer in salts. The 

 blood has nearly the same constitution as in anaemic conditions. 



In order to determine the influence exerted on the constitution 

 of the blood by the abstraction of that fluid, numerous experiments 

 have been made by Nasse on healthy animals, and by Becquerel 

 and Rodier, Zimmermann, and others, on persons in disease. The 

 results obtained showed that the specific heat, as well as the specific 

 weight of the blood, was diminished; in colour, the blood was 

 more brightly red; it coagulated more rapidly, but there was a 

 less thorough expression of the serum, which exhibited a reddish 

 or whitish turbidity. The red corpuscles, which were much dimi- 

 nished in number, showed a greater tendency to cohere. The 

 colourless cells were increased in number (Nasse, Remak), and the 

 quantity of water was considerably augmented ; and at each vene- 

 section the blood became poorer in cells than in the solid consti- 

 tuents of the serum. The quantity of the fibrin was scarcely 



