TRANSACTIONS OF SECTION D. 749 



and taking precautions that the fluids in contact -with it should have as little 

 deleterious action as was possible under the conditions of the experiment, that the- 

 direction of easier osmotic transfer was from the outer towards the inner surface, 

 the reverse of the direction of easier filtration in dead skin as demonstrated by 

 Cima. 



Contrasting, too, the action of fluids tending to preserve tissue life with that 

 of those tending to destroy it, I found that while the skin was more permeable from 

 •without inwards so long as the fluids employed did not kill its tissues, yet so soon 

 as a fluid was used that tended to destroy life, as, for instance, pure water, thats 

 then the direction of easier osmotic transfer was that of easier filtration in dead 

 skin, i.e., from within outwards. I concluded that a vital absorptive action existed 

 in the living skin, by virtue of which it was able to aid the osmotic stream if sucb 

 stream were passing in the direction from witliout inwards, for in such case the 

 vital and physical stream would be in the same direction. If, however, the osmotic 

 stream were passing in the direction from within outwards, being then contrary to 

 the direction of the vital cui-rent, it would undergo a retardation. This hypothesis 

 was much strengthened by the action of stimulant and depressant drugs upon the 

 magnitude of the osmotic current through the living skin. A stimulant, such as 

 weak alcohol, was found to increase the magnitude of a stream passing from with- 

 out inwards, i.e., in the normal direction of absorption ; while, on the other hand, 

 it diminished that of a stream caused to pass from within outwards, for here the 

 opposing vital action was against the physical stream, while in the former case it 

 had been with it. 



Using chloroform as a depressant I obtained exactly reverse effects ; with this 

 substance a stream set up from witliout inwards was diminished, wliile one passing 

 iu the reverse direction was increased. 



The crucial test of tlie hypothesis of vital absorptive force is to place exactlp 

 the same fluid upon either .«ide of a living membrane, and to obtain evidence of 

 transference of fluid across it in the normal direction of absorption in the body. 

 This I have succeeded in doing with the skin of the frog by means of a special 

 apparatus. I have suspended the skin between two layers of baudruche soaked in 

 normal saline solution, and have seen a stream of normal saline pass across from 

 the outer to the inner surface. With dead skin no such effect occurs, but only 

 imbibition at both surfaces. This action does not appear to be of electro-osmotia 

 origin. 



With the intestine of the rabbit it has also been found possible to demonstrate 

 vital absorptive action. Here the same apparatus and method have been employed 

 as in the experiments with the skin of the frog. It is necessary for success that 

 the loop of intestine selected for experiment shall be in full digestive activity as 

 judged by the state of its lacteals, blood vessels, and contents. Here, again, with 

 normal saline on either side of a piece of exsected gut, it is possible to get evidence 

 of a stream passing from within outwards so long as the tissues are alive. Scraping 

 oti" the epithelium diminishes the transfer or puts a stop to it. 



Furthermore, by adding pilocarpine to the fluids used it is possible to reverse^ 

 the direction of the stream, so that instead of a current passing from within out- 

 wards one may artificially produce one passing from without inwards ; in fact, a 

 piece of absorbing mucous membrane may have its action swamped by the 

 induction of an excess of secretory action. 



It is claimed for these experiments that they are positive as regards the occur- 

 rence of vital absorption instead of inereh/ negative as regards osmotic absorption^ 

 as has been the case with tlie results of previous observers. 



2. On Animal Heat and Physiological Calorimetry. 

 By Professor Rosenthal, of Erlangen. 



To measure the amount of heat given out by a living animal is very difficult, 

 because the common water calorimeter is not suitable for this purpose. Professor 

 Rosenthal therefore chose the air calorimeter, first invented by Scharhng and 



