FIBKIN, FAT, AND SUGAR OF BLOOD. 123 



checked by venesection. There is less fibrin in the blood of the camiv- 

 ora than in that of the herbivora. 



It has been asserted, as was mentioned before, that there is so wide a 

 difference between the fibrin of blood and muscular fibre, Fibrin is a his- 

 that we can no longer regard the latter as arising from the togeneticbody. 

 former, but must consider it merely as coagulated albumen ; and that, 

 since the action of acetic acid upon it shows its relation to gelatine, it is 

 probably more nearly related to the fibro-gelatinous than to the cellulo- 

 albuminous tissues. But, although the fact that fibrin contains more 

 oxygen than albumen seems to lend weight to such views, since oxida- 

 tion appertains to the retrograde rather than to the ascending metamor- 

 phosis, there are so many arguments in favor of the old doctrine, that 

 I think it may be regarded as thus far unshaken. Moreover, it is now 

 established beyond any doubt, that by nitrate of potash, and other salts, 

 fibrin may be transmuted into a substance analogous to albumen. 



The fats vary very much in quantity at different times. The amount 

 is usually stated at from 1.4 to 3.3 in 1000 of blood. After a meal the 

 plasma may be actually milky, through the fat globules y ariationsin 

 brought in by the chyle. We have already shown that the quantity of 

 starch will give origin to fat, and oily substances can be ob- at ' 

 tained from lactic acid itself. The nitrogenized bodies, during their de- 

 struction, likewise yield them, and it is a normal function of the liver to 

 effect the production of fat. 



The serum contains only an insignificant quantity of free fat ; but 

 there is a large proportion of saponified fat in it, as well as the lipoids 

 cholesterine and serolin. 



The view heretofore taken, that this class of substances is not histo- 

 genetic, but only respiratory, requires to be modified. There Uses of the fats 

 is reason to believe that the blood-cells themselves can not of blood - 

 be formed except in presence of oil, which is also necessary to enable ni- 

 trogenized bodies to assume the ferment action. The nuclei of cells con- 

 tain fats, as do also embryonic structures generally. Cholesterine, or 

 liver-fat, is not saponifiable. It appears as a product of disintegration, 

 increasing in quantity during acute diseases. The proportion of this sub- 

 stance increases after 40 years ; it also forms a principal ingredient in 

 biliary concretions. 



Among the special constituents of certain portions of the venous blood 

 not mentioned in the preceding tables, we ought not to over- 



,., . . T? ,*I-I-IT Liver-sugar. 



look sugar, which exists as a constant ingredient of the blood 

 contained in that part of the circulation intervening between the liver and . 

 the lungs. This, which is known as liver-sugar, may have originated in 

 the transmutation of cane-sugar, or from the metamorphosis of the mus- 

 cular tissues. It is to be remarked that the blood contains no gelatine. 



