254 



OF THE BLOOD: 



186. Under the vague term Extractive, have been included many different 

 substances which normally present themselves in only very small quantity, 

 and which are consequently difficult of detection ; but which are extremely 

 important in a physiological point of view, as the chief "factors" (to use the 

 appropriate designation of Prof. Lehmann) in the metamorphosis of animal 

 tissue, both progressive and retrograde. Amongst the latter, Urea, Creatin, 

 and Creatinin ; Uric, Hippuric, and Lactic Acids; Leucin, Ty rosin, and 

 Hypoxauthin (or Sarkiu), may be particularly mentioned. Besides the 

 foregoing, the extractive of blood generally seems to contain Sugar, or an 

 amyloid substance (Pavy), that is waiting for elimination by the respiratory 

 process, this substance being found most abundantly, however, in the blood 

 of the hepatic vein, vena cava, and pulmonary artery. As might be ex- 

 pected, the proportion of sugar in the blood is greatly affected by the diet 

 of the animal. Plosz and Tiegel 1 have described a saccharifying ferment 

 in the blood, and Hutson Ford 2 maintains that alcohol derived from the 

 decomposition of sugar is normally present. The very small amount in 

 which the Blood-constituents of this class normally present themselves, is 

 readily accounted for by the fact, that they are only enroute between the tissues 

 and the excretory organs which are destined for their elimination ; so that as 

 long as the disintegrating processes taking place in the former are balanced 

 (as they should be) by the activity of the latter, these substances are with- 

 drawn from the blood-current as fast as they are introduced into it, and no 

 sensible accumulation will occur. It can scarcely be doubted that the more 

 attentive study of this part of the blood, prosecuted upon large quantities 

 at once, will be attended with the discovery of many facts that would throw 

 great light upon the Chemistry of the histogeuetic operations, and of the 

 retrograde metamorphoses of the effete materials of the tissues. 



187. No list of the Inorganic Constituents of the Blood which has yet 

 been given expresses the precise mode in which they are grouped together. 

 The proportion which the Carbonates bear to the Phosphates, however, 

 seems to be small in human blood, as is shown by the following table, 

 founded on the analysis of Verdeil, 3 of the percentage composition of the 

 ash of the blood, after deducting the carbon still contained in it : 



In Carnivorous animals the Phosphates, in Herbivorous the Carbonates, 

 are in excess, which is obviously related to the difference of their diet. The 

 proportion of Sodium Chloride in both classes exhibits a remarkable con- 

 stancy. The normal presence of various metals in the blood has been alter- 

 nait'ly admitted and denied. Iron is unquestionably always present, and 

 amounts to 0.42 percent, of the haemoglobin present. 1 ' Millon 7 found in 100 

 parts of the insoluble residue of the ash of blood 1 to o parts of silicium, 1 



1 Pfiiiger's Arohiv, 1873, p. 391. 



2 New York Mod. Journal, vol. xv, 1872, p. 561. 



3 Ann. der Chom. und Plmrm., Bd. Ixix, p. 89. 



4 Man, forty-five years old, suffering from weak digestion. 



5 Woman, twenty-two years old, sanguineous temperament. 



' Bee Fudakow>ki, Oentralblatt f. d. Medicin Wiss., 1866, p. 705. 



7 Annul, dc Chim. ot dc Phys., *6r. iii, t. xxiii, p. 372. 



