xl THE BLOOD. 



excess of acid will re-dissolve the precipitate. This globulin is probably 

 the casein of the serum described by various authorities. 



Fatly Compounds. It has been already stated that the red corpuscles and 

 the fibrin yield a certain quantity of fat ; but a portion of the fat of the 

 blood remains in the serum, partly dissolved, and partly diffused in. the 

 liquid. It may be separated by gently agitating the serum with about a 

 third of its bulk of ether, or by evaporating the serum and digesting the dry 

 residue in ether, or in boiling alcohol. The turbid milky aspect which 

 serum often exhibits, is in most cases due to a redundance of fat, and may 

 accordingly be removed by agitation with ether. 



The fatty matters of the blood are of various kinds, viz., cholesferin, serolin, and 

 the ordinary saponifiable fats of the body (margarates and oleates) ; also, according to 

 Berzelius and Lecanu, a phosphuretted fat, similar to that found in the brain. Berze- 

 lius, indeed, is disposed to think that the blood contains every variety of fat that is 

 found in other parts of the body. Lecanu could not obtain the phosphuretted fat 

 from either the serum or the fibrin, and Berzelius therefore supposes that it is asso- 

 ciated with the red corpuscles ; he also states that the fat extracted from the fibrin is 

 different from ordinary fat. The usual quantity of fat of all kinds in 1000 parts of 

 blood is stated by Lecanu to be 515, by Simon 2 - 3, and by Nasse 2*0. 



Extractive Matters. When the serum has been freed from albuminous 

 matter by coagulation, and from fat by ether, and is evaporated to dryness, 

 a yellowish or brown mass remains, consisting of organic matters mixed with 

 salts ; the former belonging principally to the ill-defined class of substances 

 denominated "extractive matters." These have now been more carefully 

 sifted, and have yielded several definite and recognisable bodies, generated 

 in the natural process of decomposition of the tissues, or residual matters of 

 nutrition formed in the blood itself, and on their way to be excreted by the 

 kidneys. Several of the substances to be next mentioned belong to this 

 class, and as they are obviously excrementitial and transitory ingredients, 

 they are not allowed to gather in any notable quantity in the healthy state 

 of the economy. 



Creatin and Creatinin. Products of the natural " wear " of the muscles, 

 or derived from fleshy food. These compounds, which are found in muscular 

 substance and in the urine, together with hypoxanthin (also named sarkiri), 

 obtainable from the same sources, have been stated to exist in excessively 

 small quantities in the blood. 



Urea. This substance, which accumulates in the blood of animals after 

 extirpation of the kidneys or ligature of the renal arteries, as well as in 

 certain diseases, has been found in very minute quantity in the healthy 

 blood of the ox and of the calf, by Marchand and Simon, and in that of 

 roan, by Lehmann, Garrod, and others. It is, however, in such excessively 

 small quantity, that its estimation is attended with great difficulty. 



Uric Acid has been shown to exist in healthy blood by Dr. Garrod, and 

 in that of persons suffering from gout it is in such considerable quantity as 

 to be readily detected. In health its proportion is extremely small. 



Hippuric Acid is found in the blood of herbivora, and according to some 

 observers in that of man. There is, however, much doubt upon this point. 



Leucin and Tyrosin, which exist in almost all secretions and excretions, 

 probably are present in minute quantity in the blood ; but as yet they have 

 only been detected in it in disease of the liver. 



Sugar has been found in the blood of dogs, oxen, and cats, also in that 



