VENOUS. 683 



circumstances, destroyed an animal in a few seconds, was rendered com- 

 pletely innocuous by the exhausted glass; and what is singular, even 

 when the symptoms had commenced, the application of the cupping-glass 

 had the effect of speedily and completely removing them; a fact of es- 

 sential importance in its therapeutical relations. In commenting on the 

 conclusions of Sir D. Barry, Messrs. Addison and Morgan, 1 who main- 

 tain the doctrine, that all poisonous agents produce their specific effects 

 upon the brain, and general system, through the sentient extremities of 

 nerves, and through the sentient extremities of nerves only; and that, 

 when such agents are introduced into the current of the circulation in any 

 way, their effects result from the impression made upon the sensible 

 structure of the bloodvessels, and not from their direct application to 

 the brain itself, contend, that the soft parts of the body, when covered 

 by an exhausted cupping-glass, must necessarily, from the pressure of 

 the edges of the glass, be deprived for a time of all connexion, both 

 nervous and vascular, with the surrounding parts; that the nerves 

 must be partially or altogether paralysed by compression of their trunks; 

 and that, from the same cause, all circulation through the veins and 

 arteries within the area of the glass, must cease; that the rarefaction 

 of the air within the glass being still farther increased by means of 

 the small pump attached to it, the fluids, in the divided extremities of 

 the vessels, are forced into the vacuum, and, with these fluids, either a 

 part or the whole of the poison, which had been introduced ; and that, 

 in such a condition of parts, the compression, on the one hand, and the 

 removal of the poison from the wound on the other, will sufficiently 

 explain the result of the experiment, either according to the views of 

 those who conceive the impression to be made on the nerves of the 

 bloodvessels, or of those who think, that the agent must be carried 

 along with the fluid of the circulation to the part to be impressed. 



Thus far allusion has been made only to the passage of tenuous fluids 

 into the veins. Insoluble substances have, however, been detected by 

 Professor Oesterlen 2 in the mesenteric veins. On administering levi- 

 gated charcoal to animals for five or six days in succession, the blood 

 of these veins exhibited distinctly particles of charcoal of different 

 sizes, some of them so large, that it was a matter of surprise how they 

 could have made their way into the blood through the epithelium, mu- 

 cous membrane and the walls of the bloodvessels. We have no diffi- 

 culty, consequently, in comprehending how the mild chloride and other 

 insoluble preparations of mercury may be able to enter the bloodvessels 

 in this manner. 



Such would seem to be the main facts regarding the absorbent action 

 of the veins, which rests on as strong evidence as we possess regarding 

 any of the functions of the body; yet, in the treatise on Animal and 

 Vegetable Physiology by Dr. Roget, 3 we find it passed by without a 

 comment ! 



We have still to inquire into the agents of internal and adventitious 

 absorption. 



An Essay on the Operation of Poisonous Agents upon the Living Body, Lond., 1829. 



2 Heller's Archiv., Bd. iv. Heft 1, cited in Lond. Med. Gazette for July, 1847. 



3 Bridgewater Treatise, Lond., 1834, Amer. edit.,Philad., 1836. 



