THE BLOOD. 151 



albumen and fibrine of the chyle may have existed in the lymph, 

 or have been absorbed directly from the bloodvessels, it is not yet 

 necessary to controvert the conclusion of Bernard, that the fat alone 

 of the food is directly absorbed by the lacteals to form the chyle. 



The uses of the chyle need not be enlarged upon after the pre- 

 ceding remarks upon lymph. Its abundance of fat, however, ren- 

 ders it more prolific than the latter in the development of the cytoid 

 corpuscles, which are to constitute an important element of the 

 blood ; and its other elements also are developed in it, as prepara- 

 tory to their admission into the latter fluid. 



III. THE BLOOD. 



The histological relations of the blood are all-important, since 

 the elements for the development of the tissues, and for the forma- 

 tion of the fluids, except chyle, are derived from it. 



Blood is distinguished from all other animal fluids by its bright 

 cherry-red color, which, however, undergoes certain variations in 

 circumstances anon to be specified. It is a thick, slightly trans- 

 lucent fluid, with an alkaline reaction. Its specific gravity is from 

 1045 to 1075 averaging 1055 ; being less in women than in men, 

 in children than in adults, and in pregnant women than in those 

 not so. 



Normal blood solidifies or coagulates after its withdrawal from 

 the vessels, a change depending on its fibrine, and whose properties 

 have been specified on page 90. This process includes three pe- 

 riods : 1. The blood becomes viscid and gelatinous in from two to 

 four minutes after its withdrawal. 2. After seven to fourteen 

 minutes it has become a consistent jelly. 3. The fibrine contracts 

 and pours out from its fibrillated network a thin, colorless, or pale 

 yellow fluid, the serum, which rises to the surface. This increases 

 in quantity in proportion as the other part, the clot, contracts, its 

 contraction continuing for a time varying from twelve to forty 

 hours. The particulars respecting the fibrillation of the fibrine in 

 the clot have been stated on page 92, and the microscopical appear- 

 ances have been represented by Fig. 43. The clot consists of the 

 fibrine of the blood, together with the blood-corpuscles, both red 

 and colorless; and its lower part is of a darker, and the upper part 

 of a brighter red than the original blood. Arterial blood coagu- 

 lates more rapidly than venous; and the blood of women more 

 rapidly and less firmly than that of men. 



