682 ABSORPTION. 



the sulphuretted hydrogen into the abdominal cavity, death ensued. 

 On inspecting the thoracic side of the diaphragm, which was done as 

 quickly as possible, the tendinous part of it exhibited the leaden appear- 

 ance of the precipitate thrown down by sulphuretted hydrogen. The 

 experiment of J. Muller, referred to in a preceding page, establishes 

 the same fact. 



It may be concluded, then, that all living tissues imbibe liquid mat- 

 ters which come in contact with them; and that the same occurs to 

 solids, provided they are soluble in the humours, and especially in the 

 serum of the blood. But although imbibition is doubtless effected by 

 living tissues, too great a disposition has been manifested to refer all 

 the vital phenomena of absorption and exhalation to it. Even dead 

 animal membrane has been supposed to exert a positive agency in re- 

 spect to bodies placed on either side of it. In the early part of this 

 work 1 the phenomena of imbibition were investigated, and it was there 

 explained how endosmose and exosmose are effected through organic 

 membranes. A careful examination of those phenomena would lead to 

 the belief, that in many cases the membrane exerts no agency except in 

 the manner last suggested by M. Dutrochet. This is signally manifested 

 in experiments with porous, inorganic substances ; and it has been in- 

 geniously and ably confirmed by Dr. Draper, 2 of New York, who found, 

 that the phenomena were elicited, when, instead of an organic tissue, 

 fissured glass was employed. Still, as has been demonstrated, the 

 nature of the septum or membrane has in other cases a marked effect 

 on endosmose. 



Sir David Barry, 3 in different memoirs laid before the Academie 

 Royale de Mgdecine, the Academie Royale des Sciences of Paris, and 

 the Medico- Chirurgical Society of London, maintained, that the whole 

 function of external absorption is a physical result of atmospheric pres- 

 sure; and "that the circulation in the absorbing vessels and in the 

 great veins depends upon this same cause in all animals possessing 

 the power of contracting and dilating a cavity around that point to 

 which the centripetal current of their circulation is directed." In other 

 words, it is his opinion, that, at the time of inspiration, a tendency 

 to a vacuum is produced in the chest by its expansion; and as the 

 atmospheric pressure externally thus ceases to be counterbalanced, the 

 pressure without occasions the flow of blood towards the heart along 

 the veins. The consideration of the forces that propel the blood will 

 afford us an opportunity of saying a few words on this view ; at present, 

 we may only observe, that Sir David ascribes absorption, which he 

 explicitly states to be, in his opinion, extra vital, to the same cause. 

 In proof of this, he instituted numerous experiments, in which the 

 absorption of poisons from wounds appeared to take place, or to be 

 suspended, according as the wounds were, as he conceived, exposed to 

 atmospheric pressure, or freed from its influence by the application of 

 a cupping-glass. The same quantity of poison, which, under ordinary 



1 See p. 65. 



2 Amer. Journ. of the Med. Sciences, for Aug., 1836, p. 276; Nov., 1837, p. 122 ; May, 

 1838, p. 23, and August, 1838 more especially the two last. 



3 Experimental Researches on the Influence of Atmospheric Pressure upon the Circulation, 

 &c.,Lond.,1826. 



