ITS PHYSICAL, CHEMICAL, AND STRUCTURAL CHARACTERS. 263 



preceding. The most important and best established of these diversities will 

 now be enumerated. In speaking of the composition of the blood of the 

 ]'m<t Port a', 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 introduction 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 Beclard. 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 intro- 

 duction of new albuminous matter from the food. Towards the conclusion 

 of the digestive process, however, the blood of the mesenteric veins gradu- 

 ally comes to present the ordinary proportions of these two components ; and 

 in an animal that has been subjected to long abstinence, it does not differ 

 from that of the venous system in general. The quantity of extractive is 

 usually increased ; and in this part of the blood it must be, that sugar, dex- 

 trin, gelatin, and other soluble organic matters that are taken into the cir- 

 culation, are contained. Some of these have in fact been detected in it. 2 

 The fibrin of the blood of the mesenteric veins appears to be less perfectly 

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

 teric veins coagulates less firmly (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 this 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 albumen, however, it is precipitated by the metallic salts, creasote, and 

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

 albuminose, 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 albumiuose. 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 readi- 

 ness with which albuminous matter transudes from the blood in albuminuria 

 and in dropsies; this albuminous matter frequently having rather the char- 

 acters of albumiuose, than those of true albumen. 3 



197. The Splenic blood is remarkable for the marked decrease it presents 

 in the amount of solid matter it contains ; the average of twelve experi- 

 ments giving only 187.1 per 1000 of solid constituents in the splenic blood, 

 whilst the arterial blood of the same animals contained 239 parts, and the 

 jugular venous blood 201 parts.* The decrease depends upon the diminished 

 proportion of red corpuscles. The albumen and fibrin, on the other hand, 

 with the white corpuscles, are usually more or less increased in their relative 



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

 and his edition of his father's Elemens d'Anatomie Generate, pp. 265, 266. 



2 See the Researches of MM. Bouchardat and Sandras in the Supplement a 1'An- 

 nuaire de Therapeutique, 1846. 



3 See the (Jours de Physiologic of M. Paul Berard, torn, iii, p. 87. 



4 See the Analyses of Mr. Gray in his Essay, On the Structure and Uses of the 

 Spleen, 1854. 



