Royal Society, 51 



inert with reference to the body, no particle of which it can either 

 nourish or vivify until that portion of it which has been denomina- 

 ted the plasma has transuded from the vessels and arrived in imme- 

 diate contact with the particle that is to be nourished and vivified : 

 but no physiologist has yet pointed out the efficient cause of these 

 tendencies of the plasma, first, to transude through the wall of its 

 efferent vessels, and secondly, to find its way back again into the 

 afferent conduits. The explanation given by the author is that, in 

 consequence of the out-going current of blood circulating over the 

 entire superficies of the body perpetually losing a quantity of water 

 by the action of the sudoriparous glands, the blood in the returning 

 channels has thereby become more dense and inspissated, and is 

 brought into the condition for absorbing, by endosmosis, the fluid 

 perpetually exuding from the arteries, which are constantly kept on 

 the stretch by the injecting force of the heart. 



In an appendix to the paper, the author points out a few of the 

 practical applications of which the above-mentioned theory is suscep- 

 tible. Interference with the function of the skin, and principally 

 through the agency of cold, he observes, is the admitted cause of the 

 greater number of acute diseases to which mankind, in the tempe- 

 rate regions of the globe, are subject. He who is said to have suf- 

 fered a chill, has, in fact, suffered a derangement or suppression of 

 the secreting action of his skin, a process which is altogether indis- 

 pensable to the continuance of life ; and a disturbance of the general 

 health follows as a necessary consequence. Animals exposed to the 

 continued action of a hot dry atmosphere die from exhaustion ; but 

 when subjected to the effects of a moist atmosphere of a temperature 

 not higher than their own, they perish much more speedily ; being 

 destroyed by the same cause as those which die from covering the 

 body with an impervious glaze ; for, in both cases, the conditions re- 

 quired for the access of oxidized, and the removal of deoxidized 

 plasma, are wanting, and life necessarily ceases. The atmosphere of 

 unhealthy tropical climates differs but little from a vapour-bath at 

 a temperature of between 80° and 90° Fahr.; and the dew-point in 

 those countries, as for example on the western coast of Africa, never 

 ranges lower than three or four" degrees, nay, is sometimes only a 

 single degree, below the temperature of the air. Placed in an atmo- 

 sphere so nearly saturated with water, and of such a temperature, 

 man is on the verge of conditions that are incompatible with his ex- 

 istence : conditions which may easily be induced by exposure to fa- 

 tigue in a humid atmosphere under a burning sun, of other causes 

 which excite the skin while they prevent the exercise of its natural 

 function. The terms Miasma and Malaria may, according to the 

 author, be regarded as almost synonymous with air at the tempera* 

 ture of from 75° to 85° Fahr., and nearly saturated with moisture. 



2. A paper was also read, entitled, " On the Cause of the reduction 

 of Metals from solutions of their salts by the Voltaic circuit." By 

 Alfred Smee, Esq., F.R.S., Surgeon to the Bank of England. 



The reduction of a metal from its saline solution by the agency of 

 voltaic electricity, has, the author states, been explained in three 



E2 



