OP THE FLUIDS. . 81 



During the washing and squeezing of the clot, both the free 

 colouring matter, and particles that remain entire, and that 

 contain white globules in their centres, are carried away by 

 the water at the same time. 



The blood, then, contains three principal materials, the se- 

 rum, the white globules, and the colouring matter that en- 

 velops them: the two last united in the fluid blood, and form- 

 ing the colouring particles, separate, in a great measure, soon 

 after the blood is drawn from the vessels. These materials 

 are in very different proportions, according to the various cir- 

 cumstances of age, sex, constitution, disease, &c. &e. : in the 

 adult and healthy man, the dried, colouring particles consti- 

 tute a little more than an eighth of the total weight of the 

 blood. 



75. The serum has a pale, yellowish green colour; it has 

 the taste, smell, and feel of blood; it is alkaline; it coagulates 

 at about 69. C. It then resembles the white of a cooked egg, 

 and contains in its vacunse, a substance that has been taken for 

 gelatine, and which appears to be mucus. The constituent 

 parts of the serum are, water, albumen, soda, and salts of soda. 

 According to M. Brand, we may consider the serum, which is 

 a liquid, and almost pure albumen, as an albuminate of soda 

 with an excess of base. The coagulation appears to depend 

 upon the neutralization of the souda necessary to its fluidity; 

 alcohol and most of the acids, produce this coagulation by re- 

 moving the soda; and by the action of the galvanic pile as well 

 as by that of heat, the soda transforms a small portion of the 

 albumen into mucus, while the remainder coagulates. The 

 albumen and the serum itself, still present some peculiarities 

 worthy of remark; it is that coagulated albumen, presents glo- 

 bules under the microscope, and that the serum, preserved in 

 a liquid state, in a proof glass for a few days, gradually pro- 

 duces globules, that are deposited at the bottom, and which ex- 

 perience a singular movement of ascent and descent, on heat- 

 ing the glass by holding it in the hand; we must also observe, 

 that coagulated albumen, has the closest analogy with fibrine, 

 from which, perhaps, it does not in any way differ. 

 76. The cruor of the blood, or the colouring matter obtain- 



