30 



ABSORPTION. 



quence of which the constituents may be more 

 completely mixed together, and to a certain 

 degree of pressure and temperature to which it 

 is exposed, which may modify any spontaneous 

 change that might otherwise take place in the 

 arrangement of its elements. But to whatever 

 cause it may be referred, we must consider the 

 chemical and physical change in the nature of 

 the chyle as one effect produced by the lacteals, 

 as well as the progressive motion which is im- 

 parted to their contents. 



In the present state of our knowledge on the 

 subject, it remains for us to consider whether 

 we have any independent evidence of the exist- 

 ence of the muscular fibres of the absorbent 

 vessels, whether, if their existence be proved, 

 and their contractility thus established, it 

 would be necessary for us to search out for 

 other causes of the effects, and lastly, to what 

 other principle the acknowledged effects might 

 be attributed, should it appear, upon full con- 

 sideration, that the assigned cause is insufficient 

 or inadequate. 



The above considerations lead us to give an 

 account of the hypothesis of the action of the 

 absorbents, which has been proposed by M. 

 Magendie. He had ascertained, by a previous 

 train of experiments, that according to the con- 

 dition of the system as to depletion or plethora, 

 the process of absorption was respectively acce- 

 lerated or retarded. Hence he draws the con- 

 clusion, which, however, we conceive not to be 

 a necessary consequence of the premises, that 

 the function depends on a mere mechanical 

 principle, independent of any vital action. The 

 mechanical principle to which he has recourse, 

 and which he thinks can alone account for the 

 effect, is that of capillary attraction ; but this he 

 conceives not to take place from the open 

 mouths of the vessels, according to the ordinary 

 conception of the subject, but that the fluid is 

 imbibed by the substance of the vessel itself, 

 and is, as it were, filtered through its pores.* 

 He explains its further progress by supposing, 

 that when it has entered these pores, it is car- 

 ried forwards by the current of the fluid pre- 

 viously in the vessel. 



To prove his idea of the permeability of the 

 parietes of the vessels, he instituted a series of 

 experiments on the veins of an animal shortly 

 after death, when he found that they were 

 capable of imbibing and transmitting certain 

 fluids with which they were placed in contact. 

 Still farther to substantiate the hypothesis, 

 M. Magendie repeated a set of analogous ex- 

 periments on the vessels of a living animal. 

 They consisted essentially in detaching a por- 

 tion of one of the great veins, and applying to 



* Journ. t. i. p. 6 et seq. and Diet, de Med. 

 et Chir. Prat. " Absorption," t. i. p. 91 et seq. 

 The doctrine of transudation was maintained by 

 many of the older physiologists ; see Kauw Boer- 

 haave, de Persp. ; also Haller, El. Phys. ii. 2. 23 ; 

 more lately it was supported by W. Hunter, Med. 

 Com. ch. 6; by Walter, ubi supra, 28 . . 35 ; and 

 by Mascagni, ps. 1. sect. i. and is zealously main- 

 tained by his commentator Bellini, t. i. not. 4. 

 p. 33 . . 0. The " penetrabilite" of the cellular tex- 

 ture was one of the fundamental doctrines of Bordeu, 

 Recherches sur le Tissue muqueux, $ 72. 



its surface the solution of some narcotic or 

 poisonous substance, the effects of which were, 

 in a short time, manifested in the system at 

 large.* 



This doctrine of imbibition and transudation 

 has been embraced by M. Fodera, who has 

 endeavoured to confirm the opinion of M. Ma- 

 gendie by additional experiments, which he 

 conceives tend directly to prove that the vessels 

 of the living body possess this power of im- 

 bibition. The method which he adopted to 

 prove this point, in the most unequivocal man- 

 ner, was to inject into two separate cavities of 

 the body two fluids, which by their union pro- 

 duce a compound, the presence of which may 

 be easily detected, and which could be formed 

 by no other means except by this union. For 

 example, into the cavities of the pleura and 

 the peritoneum were respectively injected the 

 solutions of the ferro-prussiate of potash and of 

 the sulphate of iron, when it was found, after a 

 certain length of time, that various membranes 

 and glands, connected with the thorax and the 

 abdomen, were tinged with a blue colour. 



M. Magendie afterwards performed an ex- 

 periment, which seemed more directly to bear 

 upon the question, where a solution of the 

 ferro-prussiate was retained in a portion of the 

 intestine, at the same time that its external 

 surface was placed in contact with a solution 

 of the sulphate of iron : the part was then ex- 

 posed to the galvanic influence, the result of 

 which was that a blue tinge was communicated 

 to the sulphate. We are further informed, that 

 according to the direction of the galvanic cur- 

 rent, the blue colour was produced either in 

 the sulphate or in the ferro-prussiate. From 

 these experiments M. Fodera draws the con- 

 clusion, that the processes of absorption and of 

 exhalation may be referred to the mechanical 

 operations of imbibition and transudation, which 

 take place through the pores or capillary open- 

 ings of the various textures of the body.f 



On these experiments, and the conclusion 

 deduced from them, we shall remark, that the 

 facts appear to prove that membranes, perhaps 

 during life, and certainly after death, before 

 any visible decomposition has taken place, are 

 capable of transmitting fluids through their tex- 

 ture; but we conceive that the analogy between 

 this case and that of the entrance of chyle into 

 the lacteals is so incomplete, that we can draw 

 no inference from the one of these events which 

 can be fairly applied to the other. Both the 

 mechanical and the physiological properties of 

 membranes and vessels differ much from each 

 other, while the nature of the fluids employed in 



* Journ. t. i. p. 9, 10. 



t " Recherches sur 1'Absorption et 1'Exhalation," 

 and Magendie's Journ. t. iii. p. 35 et seq. ; see, also 

 .Med. Repos. v. xix. p. 419, et Med. Journ. v. xix, 

 p. 488, 9. On this subject see the rrmarks of 

 Tiedemann, Traite de Physiol. par Jourdan, 168. 

 p. 242. Mr. Mayo remarks, that the principle of 

 imbibition and transudation affords a more easy ex- 

 planation of the experiments of MM. Magendie 

 and Segalas, than that of venous absorption ; Phy- 

 siol. (3rd ed.) p. 97 et seq. See the remarks and 

 objections of Sir D. Barry, Exper. Researches, 

 p. 80 . . 2 et alibi ; also Elliotson's Physiol. p. 133. 



