182 OF THE BLOOD. 



from the blood of the hepatic vein, and both of these differ from the blood of the 

 jugular. So, again, the blood of the splenic vein differs from all the preceding ; 

 and so must the blood of the renal vein, although this latter difference has not 

 yet been demonstrated by direct analysis. The most important and best esta- 

 blished of these diversities will now be enumerated. In speaking of the compo- 

 sition of the blood of the Vena Portse, it must be remembered that this consists 

 of two very distinct factors, namely, the blood of the gastric and mesenteric veins, 

 and the blood of the splenic vein; the former having been altered by the intro- 

 duction of solid and liquid alimentary matters, and the latter by its circulation 

 through the spleen. These, therefore, ought to be separately studied ; and this 

 has been done by M. Jules Be'clard. 1 The characters of the blood returning by 

 the Gastric and Mesenteric veins from the walls of the alimentary canal, are' of 

 course affected by the stage of the digestive process, and by the nature and amount 

 of the absorbable matters. As compared with the ordinary venous blood, the 

 total quantity of its solid constituents is lowered during the early part of the 

 digestive process, by the dilution it suffers through the imbibition of liquid; and 

 this diminution is especially remarkable in the corpuscles, the relative proportion 

 of albumen being increased by the introduction of new albuminous matter from 

 the food. Towards the conclusion of the digestive process, however, the blood 

 of the mesenteric veins gradually comes to present the ordinary proportions of 

 these two components; and in an animal that has been subjected to long absti- 

 nence, it does not differ from that of the venous system in general. The quan- 

 tity of extractive is usually increased ; and in this part of the blood it must be, 

 that sugar, dextrin, gelatin, and other soluble organic matters that are taken 

 into the circulation, are contained. Some of these have in fact been detected 

 in it. 3 The fibrin of the blood of the mesenteric veins appears to be less per- 

 fectly elaborated than that of the blood in general ; for the blood of the mesen- 

 teric veins coagulates less perfectly (having been erroneously asserted by some 

 not to coagulate at all) ; and its fibrin, when separated by stirring, shows a 

 marked deficiency in tenacity, and liquefies completely in the course of a few 

 hours. A part of the albuminous constituent of the blood does not present the 

 characters of true albumen, for it is not precipitated by heat or by nitric acid, 

 and the precipitate thrown down by alcohol is redissolved by water; like albu- 

 men, however, it is precipitated by the metallic salts, creasote, and tannin. 

 This substance, which has been distinguished by M. Mialhe as alluminose, 

 further differs from true albumen in the facility with which it traverses organic 

 membranes; for these resist the passage of albumen, while they are freely 

 transuded by albuminose. And it is affirmed by M. Mialhe, that the want of 

 that conversion of albuminose into albumen, which ought to take place as part 

 of the assimilating process, is one cause of the readiness with which albumin- 

 ous matter transudes from the blood in albuminuria and in dropsies; this albu- 

 minous matter frequently having rather the characters of albuminose than 

 those of true albumen. 3 



168. On the other hand, the blood of the Splenic vein exhibits a notable 

 diminution in the proportion of red corpuscles, whilst its albumen is greatly 

 augmented, the total amount of its solid matter differing but little from that of 

 arterial blood; as is shown by the following comparative statement of the pro- 

 portions of the water and the solids- of the blood of the same animal in different 

 parts of its circulation. 



1 See his Memoir in the "Arch. Gen. de Med.," 4 e serie, torn, xviii., p. 322, et seq. ; 

 and his edition of his father's "Elements d' Anatomic Generale, " pp. 265, 2\H>. 



2 See the Researches of MM. Bouchardat and Sandras, in the "Supplement al'Annuaire 

 de Therapeutique," 1846. 



3 See the "Cours de Physiologic" of M. Paul Berard, torn. iii. p. 87. 



