110 Mitchell on the Penetrativeness of Fluids. 



which would have stained the whole of the lining membrane of the 

 cavity, and dyed the bladder. This experiment forcibly reminded 

 us of that where the internal surface of a gum elastic bag holding 

 lead water, was stained black by sulphuretted hydrogen, while the 

 solution continued pellucid. 



In another experiment on a cat, a solution of acetate of lead was 

 placed in the thorax, and sulphuretted hydrogen in the abdomen. 

 Almost immediately, on the entrance of the sulphuretted hydrogen 

 into the abdominal cavity, death ensued, with the same dilatation 

 of pupil as before. On inspecting the thoracic side of the dia- 

 phragm, which was done as quickly as possible, the tendinous part 

 of it displayed the leaden aspect of the precipitate by sulphuretted 

 hydrogen. Many years ago, in 1823, while engaged in investi- 

 gating MAGENDIE'S theory of venous absorption, I coloured the 

 diaphragm of a living cat blue, by placing a solution of prussiate of 

 potash on one side, and that of sulphate of iron on the other. At 

 that time I supposed the effect to be vascular, but the experiments 

 on membranes of gum elastic afford an explanation which more 

 rationally refers it to organic molecular infiltration ; for, in such 

 membranes, vessels cannot possibly exist at all ; and as animal 

 membranes act in a manner so perfectly accordant with that of the 

 coagulated vegetable juice, it would be judging against evidence 

 to refer their agency to widely different causes. At the same rela- 

 tive rates, with the same power, and that a great one, they could 

 scarcely act, in obedience to causes so dissimilar as those alluded to. 



Every one who has read the beautiful memoir of Dutrochet, on 

 * L'agent immediat du Mouvement Vital, *c.,' and who has, as 

 nearly all have, suffered their belief to be swayed by his eloquence 

 of fact, method, and style, will, on a cursory glance at the experi- 

 ments detailed in this paper, refer them to the * NEW POWER* so 

 ably contended for by the French naturalist. That they depend on 

 the same power cannot be reasonably questioned, whether that power 

 be one long known or recently discovered. In his experiments made 

 exclusively on liquids, and developed with surpassing good fortune 

 and sagacity, he proved the transmission of liquids through animal 

 membranes, and saw them penetrating, too, at different rates, some 

 solutions passing rapidly, some with greater slowness, some in 

 scarcely appreciable quantity, and some never passing at all. Their 

 force, too, he found to be of estimable amount. In fact, every 

 aspect of the two sets of experiments tends, more and more clearly, 

 to induce a reference of them to one and the same cause, whatever 

 that cause may be. Although the facts presented by him demon- 



