CHEMICAL COMPOSITION. xxxix 



duct, he names fibrinogenous substance, the other fibrinoplastic substance. 

 In the coagulation of hydrocele-fluid, the former, or fibrinogen, is already 

 there, while the fibrinoplastin is supplied from the blood. It is not that 

 the latter converts albumen into fibrin, for, after a certain amount of fibrin 

 has been coagulated from the serous fluid, no further addition will generate 

 more, although abundance of albumen remains; and again, a given quantity 

 of fibrinoplastin will not coagulate with equal rapidity and intensity any 

 amount of fluid containing fibrinogen. In short, the fibrinoplastic sub- 

 stance seems not to operate as a ferment or by catalysis, but by combining 

 with the other necessary ingredient. Now Schmidt has shown that the 

 fibrinoplastic matter presents all the chemical characters of globulin, and is 

 in fact nothing else than that substance. Accordingly, he finds, as already 

 stated, that blood-crystals are highly fibrinoplastic. This globulin is not 

 restricted to the red corpuscles ; it exudes from them into the plasma in the 

 coagulation of the blood, and a residual portion remains in the serum when 

 the process is over ; globulin doubtless exists also in the pale corpuscles. 

 Nor is it confined to the blood. From chyle and lymph, from the aqueous 

 humour of the eye and watery extract of the cornea, from the vitreous 

 humour and crystalline lens, from connective tissue, and from saliva and 

 synovia, a substance may be obtained having the same re-actions and the 

 same fibrinoplastic power. Fibrinogen may be thrown down from hydrocele- 

 fluid by a mixture of alcohol and ether ; it very closely resembles globulin 

 in its chemical relations, only it is less soluble in acids and alkalies, and less 

 energetic in all its re-actions. Of course, it exists in blood-plasma, and in 

 the process of coagulation of the blood combines with globulin, transuded 

 from the corpuscles, to form the fibrin of the clot.* 



Serum. This is a thin and usually transparent liquid, of a pale yellowish 

 hue ; it is, however, sometimes turbid, or milky, and this turbidity may 

 depend upon different conditions, but most commonly on excess of fatty 

 molecules. The specific gravity of serum ranges from 1025 to 1 030, but is 

 most commonly between 1027 and 1028 (Nasse), and is more constant than 

 that of the blood. The solid contents of the serum are not more than 8 or 

 9 in 100 parts ; the proportion of water being, for males 90 '88, and for 

 females 91 '71. It is always more or less alkaline. When heated, it 

 coagulates, in consequence of the large quantity of albumen it contains ; 

 and after separation of the albumen, a thin saline liquid remains, some- 

 times named " serosity." The following ingredients are found in the 

 serum. 



Albumen. This principle is considered to be combined with soda as an 

 albuminate ; its quantity may be determined by precipitating it in the 

 solid form by means of heat or alcohol, washing with distilled water, 

 drying, and weighing the mass. Its proportion is about 80 in 1000 of 

 serum, or nearly 40 in 1000 of blood. 



Globulin. When serum is diluted with about ten times its bulk of 

 distilled water, and subjected to a stream of carbonic acid, the liquid 

 becomes turbid, and globulin is precipitated. It may also be obtained from 

 the diluted serum by the cautious addition of acetic acid, but the least 



* Schmidt, Alex., in Reichert & Du Bois Raymond's Archiv. fur Anat. n. Physiol., 

 1861 and 1862. For a lucid account of the progress and present state of this question, 

 founded on a confirmatory repetition of Buchanan's and of Schmidt's fundamental experi- 

 ments, see an article on "the Coagulation of the Blood," [by Dr. Michael Foster,] in the 

 Natural History Review for 1864, p. 157. 



