ON THE BALANCE OF THE VITAL ECONOMY. 431 



of the most important and fundamental character; since, as elsewhere 

 shown, it enters largely into the composition of the muscles, nerves, and 

 glandular structures, whilst it also affords the chief material for the produc- 

 tion of the fibrin, and hsematoglobulin of the Blood. It appears, however, 

 to be itself entirely destitute of formative capacity ; for in no exudation 

 which is purely serous do we ever trace the slightest indication of organiza- 

 tion ; and its conversion into the various kinds of tissues, therefore, must be 

 entirely due to their own power of appropriating and transforming it. The 

 great function of the Albumen of the blood, then, is to supply the material 

 for these various transformations ; and we accordingly find that whatever 

 other changes the fluid may undergo, whether it loses it fibrin or its red cor- 

 puscles, or both, albumen is still present in abundance. Its ultimate source 

 is to be found in the food ; but the serous liquid which percolates the tissues 

 of the body may be regarded as a reserve store, to be drawn upon in case of 

 need, furnishing albumen to the blood when it might otherwise be deficient; 

 and thus perhaps it is, that abstinence or repeated losses of blood do not 

 produce the degree of depression in the proportion of albumen, which might 

 be expected from the very marked reduction they effect in that of the cor- 

 puscles. When an excess of Albuminous matter is ingested as food, the in- 

 jurious effects which might follow the too great augmentation of this con- 

 stituent of the Blood, appear to be averted by the readiness with which it 

 undergoes retrograde as well as progressive metamorphosis ; for, if not 

 speedily subjected to the latter change, it appears in the ceaseless inter- 

 change which takes place between the contents of the cells of which the body 

 is composed and the fluids, as the lymph and blood bathing their external 

 surfaces, to be affected by decomposing agencies, and to be eliminated from 

 the system by the excretory apparatus, under the form of urinary and biliary 

 matter. From various considerations it would appear the albuminous com- 

 pounds in their retrograde metamorphoses are capable of breaking up into 

 two groups of substances, of which one contains the whole of the nitrogen, 

 whilst the other is composed of carbon, hydrogen, and oxygen alone. The 

 former are ultimately eliminated from the body as urea or some analogous 

 compound ; the latter are either stored up in the form of fat or are dis- 

 charged after oxygenatiou in the form of carbonic acid and water. Of the 

 former series, we know that whilst Leucin (C 6 H, 3 NO 2 ), Tyrosin (CgH^NO^), 

 and Glycin (C 2 H 5 NO,), can be artificially formed by the action of alkalies 

 or acids upon albumen, or even appear during its spontaneous decomposi- 

 tion ; these same substances can a)so be obtained from various tissues of the 

 body, and are always most abundant in those organs in which interstitial 

 changes are most active, as in the spleen and liver. 1 From muscular tissue, 

 again, Inosinic Acid (C 10 H, 4 N 4 O U ), Creatin (C 4 H 9 N 3 O 2 ), and the urinary 

 constituent Creatiniu (C^.N.^!), can be directly obtained. The relation 

 of Inosinic Acid and of Allantoin (C 4 H 6 N 4 O 3 ), found in the urine of women 

 during gestation and in new-born children, to Uric Acid and Urea, which 

 are the ultimate products of the decomposition of the albuminous compounds, 

 is very intimate; whilst as regards Creatiu, the researches of Sarokow 2 in- 

 dicate that during active muscular exertion it is converted into Creatinin, 

 or at all events that, in muscles exhausted by action, a greatly increased 

 proportion of Creatiuin is generated; and it is well known that both of 

 them are convertible by chemical agents into Urea. 3 The evidence of the 



1 Glycin has not, indeed, beon obtained in the separate state, but it enters into 

 the composition of the glycocholic acid of the bile. The further decomposition of 

 leucin in the laboratory by fermentation and oxidizing agents, yields the volatile 

 fatty acids well known to occur in glandular organs and in the blood. 



a Virchow's Archiv, 1863, p. 544. 3 Fownes's Chemistry, 1861, p. 670. 



