So THE BLOOD. 



other hand, the addition of an excess of water to the blood 

 is quickly followed by its more copious excretion in sweat 

 and urine. And these means for adjusting the proportion 

 of the water find their purpose in maintaining certain im- 

 portant physical conditions in the blood ; such as its proper 

 viscidity, and the degree of its adhesion to the vessels 

 through which it ought to flow with the least possible 

 resistance from friction. On this also depends, in great 

 measure, the activity of absorption by the blood-vessels, 

 into which no fluids will quickly penetrate, but such as are 

 of less density than the blood. Again, the quantity of 

 water in the blood determines chiefly its volume, and 

 thereby the fulness and tension of the vessels and the 

 quantity of fluid that will exude from them to keep the 

 tissues moist. Finally, the water is the general solvent of 

 all the other materials of the liquor sanguinis. 



It is remarkable, that the proportion of water in the 

 blood may be sometimes increased even during its abstrac- 

 tion from an artery or vein. Thus Dr. Zimmerman in 

 bleeding dogs, found the last drawn portion of blood 

 contain 12 or 13 parts more of water in lOOO than the 

 blood first drawn; and Polli noticed a corresponding 

 diminution in the specific gravity of the human blood 

 during venesection, and suggested the only probable ex- 

 planation of the fact, namely, that during bleeding, the 

 blood-vessels absorb very quickly a part of the serous 

 fluid with which all the tissues are moistened. 



The albumen may vary, consistently with health, from 60 

 to 70 parts in the IOOO of blood. The form in which it 

 exists in the blood is not yet certain. It may be that of 

 simple solution as pure albumen : but it is, more probably, 

 in combination with soda, as an albuminate of soda ; for, 

 if serum be much diluted with water, and then neutralized 

 with acetic acid, pure albumen is deposited. Another 

 view entertained by Enderlin is that the albumen is dis- 

 solved in the solution of the neutral phosphate of sodium. 



