38 APPENDIX; 



menon whose energy is in a direct ratio of the affinity of the fluid for the surface of the 

 tube, and in an inverse ratio with the diameter of the latter. 



" It appears to me then,'* he adds, " beyond doubt that all the blood-vessels, venous 

 and arterial, whether duad or living, small or great, present, in their parietes, a physical 

 property calculated to account for the principal phenomena of absorption. To affirm 

 that this property is alone able to produce all the phenomena of absorption would be to 

 go beyond what is warranted by a correct logic ; but in the present state of facts on the 

 subject, I know not any thing which weakens the inference which I have drawn, but- 

 many which may be adduced in its support." 



" By this method of explaining absorption," he observes, ts we solve a number of 

 other phenomena in the living system otherwise inexplicable : for example, the princi- 

 ple on which dropsies are cured, the relief from congestion and inflammation produced 

 by blood-letting, the want of efficacy in medicines during those febrile states of the sys- 

 tem in which the vascular system is greatly distended: the propriety of that practice 

 which institutes blood-letting and purging prior to the administration of other active 

 medicinals, the rationale of both partial and general dropsies, under circumstances of 

 cardiac or pulmonary diseases ; the use of ligatures upon limbs after the bite of veno- 

 mous animals, in order to prevent the consequences of such accidents," &c. 



That absorption takes place exclusively through the medium of the veins cannot, in 

 our' opinion, be granted to any part of the body or to any organ, excepting to the brain. 

 As respects this organ, we believe that sufficient proofs exist of this function being 1 

 performed entirely by this set of vessels. {See t/tc Note on the Structure and Functions 

 of the Jfiwin.') 



This very interesting subject has been further investigated by Messrs. Segales and Fo- 

 dera. Journ. de PhysioL .April 1822, and Jan. 1823.) The latter physiologist entered 

 upon a series of experiments, which, although they appear not to us fully to substaniate 

 the opinion of Magendie that venous absorption takes place by capillary attraction, 

 seem nevertheless to show that this process, or one similar to it, actually exists to a 

 certain extent in the living body, and that though it may be subordinate to more ener- 

 getic influences, it should not be altogether overlooked in our inquiries into the ope- 

 rations of the animal economy. 



Mr. Fodera's end, in his experiments, has been to demonstrate that exhalation, which 

 he calls transudation : and absorption, which he names imbibition, are similar phenomena, 

 owing to the capillary attraction of the parietes of the different vessels, owing to their 

 porosity, operating, in the first case, from the interior of the vessels to the exterior, and 

 in the second from the exterior to the inferior. 



Magendie conceived he had already proved that venous absorption takes place by 

 imbibition, and came to the conclusions which we have now stated. One of his experi 

 ments consisted in completely isolating a portion of vein, and placing its- surface in 

 contact with an active poison : its presence was soon discovered at the internal surface 

 of the vessel. M. Fodera then inverscd the experiment. He injected a poisonous sub- 

 stance, with every proper precaution, into the interior of a portion of artery comprised 

 between two ligatures, and isolated frcm its cellular tissue, its lymphatics, and its vasa 

 vasomm .- poisoning took place. He obtained the same result by filling with poison a 

 portion of an artery, vein, or of intestine, removing and placing them either at the sur- 

 face of a wound made in another animal, or in the abdominal cavity. In these different 

 experiments, the rapidity ot the poisoning appeared to vary according to the age and 

 kind of animal ; the thickness and length of the portion of vessel or intestine, its 

 greater or less distension : the more or less perfect solution of the injected matter, &c. 



Mr. Fodera has also seen gases absorbed in the same manner. He placed on the pe- 

 ritoneal cavity of a rabbit sulphurretted hydrogen, enclosed in a portion of intestine re- 

 moved from another animal ; and at the end of some time, symptoms of poisoning ma- 

 nifested themselves, and the sulphurretttd hydrogen was no longer found in the intes- 

 tine. 



If, in a living 1 animal, an artery or vein is exposed, an oozing is observed to take place 

 through its parietes. This oozing augments, if a ligature be applied to the vessel : dif- 

 i'erent dropsies may likewise be produced by the ligature of the great venous trunks. 



Mr. Fodera concludes, from these facts, that exhalation is only a phenomenon of 

 transudation through the parietes of tjie vessels, as many physicians had thought, be- 

 fore the exhalent vessels were imagined. 



The following experiments prove that, at least, on the dead body, transudation of li- 

 quids may take place at the same time from the interior to the exterior, and rice versa 

 through the vascular or intestinal parietea. Fodera filled a portion of a rabbit's in- 

 testine v.'Uh a solution of prussiate of potass, and plunpred it into a solution of'hydrochlo- 



