USES OF THE SEVERAL CONSTITUENTS OF THE BLOOD. 529 



and a little Phosphate and Oxide of Iron. Of these, the chief part are dissolved in the 

 Serum ; but the Earthy Phosphates, which are insoluble by themselves, are probably com- 

 bined with the Protein e-compounds ( 113); and the iron is contained, chiefly or entirely, 

 in the red corpuscles. It is difficult to speak with certainty, from the examination of the 

 ashes of the blood, as to the state of the Saline constituents of the circulating fluid. Thus 

 the Serum has an alkaline reaction ; and this has been supposed to be due to the presence 

 of alkaline Carbonates. Moreover the presence of the Lactates of potass and soda has been 

 usually asserted. On the other hand, the recent analyses of Enderlin, which have been con- 

 firmed by Liebig, would indicate that the alkaline reaction is entirely due to the presence of 

 the tribasic Phosphate of soda ; and that no alkaline carbonates or lactates exist in the blood. 

 This discrepancy seems partly due to the mode of analysis employed; for it has been lately 

 pointed out by Dr. G. O. Kecs,* that although the ashes of the entire mass of blood do not 

 effervesce on the addition of an acid, effervescence takes place when acid is added to the 

 ashes of the serum, showing the existence in it, either of alkaline Carbonates, or of Lactates, 

 which have been reduced to the state of Carbonates by incineration. It appears that, when 

 the entire mass of blood is incinerated, enough phosphoric acid is produced from the phos- 

 phorized fats, to neutralize the alkaline carbonates, and thus to prevent their presence from 

 being recognized. There can be no doubt, however, that the tribasic Phosphate of Soda 

 exists as such in the blood, and contributes to its alkaline reaction ; and it appears to confer 

 upon the liquid a special power of absorbing Carbonic Acid. 



e. Some very interesting observations upon the state of the blood soon after a meal, have 

 been recently made by Drs. Buchanan and R. D. Thompson. They are confirmatory of the 

 belief generally entertained, that the milky appearance, sometimes presented by the Serum, 

 is due to the admixture of Chyle. When a full meal containing oily matter is taken after 

 a long fast, and a small quantity of blood is drawn previously to the meal and at intervals 

 subsequently, the Serum, though quite limpid in the blood first drawn, shows an incipient 

 turbidity about half an hour afterwards^ this turbidity increases for about six hours subse- 

 quently, after which it usually begins to disappear. The period at which the discoloration 

 is the greatest, however, and the length of time during which it continues, vary according 

 to the kind and quality of the food, and the state of the digestive functions. Neither starch, 

 nor sugar, nor proteine-compounds, alone or combined, occasion this opacity in the chyle ; 

 but it seems entirely dependent upon an admixture of oleaginous matter with the food. 

 There are few ordinary meals, however, from which such matter is altogether excluded. 

 When such milky serum is examined with the Microscope, the opacity is found to be due 

 to the presence of an immense number of exceedingly minute granules, resembling in ap- 

 pearance those which form the " molecular base" of the chyle. They seem to be composed 

 of two chemically-distinct substances; for when the milky serum is agitated with ether, a 

 part is dissolved, whilst another portion remains suspended ; and this latter is soluble in 

 caustic potass. The former, therefore, appears to be identical with the "molecular base" of 

 the Chyle, and to be of an oily or fatty nature ; whilst the latter belongs to the proteine- 

 compounds. The Crassamentum of such blood often exhibits a pellucid fibrinous crust, 

 sometimes interspersed with white dots ; and this seems to consist of an imperfectly-assi- 

 milated proteine-compound, analogous to that found in the serum. The quantity of this varies 

 according to the amount of the proteine-compounds present in thefood.f It is evident from 

 these experiments, that the assimilating process is by no means completed, at the time of 

 the passage of the Chyle into the Blood ; and it would seem that the return of the trans- 

 parency of the serum is due to the gradual removal of the superfluous fatty matter through 

 the respiratory process, whilst the proteine-compound, of which part of the granules are 

 composed, is gradually reduced to a state of perfect solution. 



/. The occasional presence of Sugar, even in healthy blood, when a large quantity of 

 saccharine matter exists in the food, appears to be now well established. But it seems to 

 be commonly transformed, either into lactic acid, or into fatty matter, previously to its recep- 

 tion into the circulating current. This last transformation is partly effected through the 

 agency of the Bile ; as will be shown hereafter ( 835). 



698. It cannot be doubted that, upon the due admixture in the Blood of all 

 these elements, the regular performance of its actions is dependent. In regard 

 to its physical properties merely, it is easily shown that a slight alteration may 

 produce the most injurious consequences; for a certain degree of viscidity has 

 been found (by the experiments of Poisseuille) to favour the passage of fluid 

 through capillary tubes; and thus, if the viscidity of the blood be diminished 

 by a loss of part of its fibrine, stagnation of the current, and extravasation of a 



* On the Analysis of the Blood and Urine, p. 30. 

 f Medical Gazette, Oct. 10, 1845. 

 45 



