PHYSICAL AND VITAL PROPERTIES OF TISSUES. 45 



Poisseuille found by experiment, that there was endosmose through 

 animal tissues, from the serum of the blood to Seidlitz water, and 

 to solutions of sulphate of soda and common salt. This is precisely 

 what happens when these substances are used internally as medi- 

 cines ; the rejected excrements contain large quantities of albumen. 

 In this case, it must be admitted that endosmose takes place through 

 the capillary vessels of the intestine, from the serum of the blood 

 to the saline solution introduced into the intestinal canal. The ex- 

 periments of Poisseuille have been confirmed by Bachetti, who also 

 proved that the rapidity of endosmose is considerably increased, 

 when one of the fluids is in motion and constantly renewed, as is 

 the case with the blood circulating through the capillaries. The 

 most remarkable fact discovered by Poisseuille, is that of the influ- 

 ence exercised by the muriate of morphia. When this substance is 

 added to saline solutions, it very considerably weakens the en- 

 dosmose from the serum to the solution, and ultimately changes the 

 direction of the current. This has also been confirmed by Bachetti, 

 and upon this is based an hypothesis as to the modus operandi of 

 morphia, and of the preparations of opium in diarrhoea, as well as 

 of the constipation they produce. 



The animal membranes exercise the property of j/:'wosf i^?/, or im- 

 bibition, in reference to gases as well as fluids ; and the tendency of 

 dissimilar gases to become diffused among each other, manifests it- 

 self even through compound textures. As was shown to be the 

 case with liquids, there is a double current, when two dissimilar 

 gases are separated by a porous septum, and the predominant cur- 

 rent is that which has the greatest attraction for the septum. In 

 respiration, this phenomenon occurs at every inspiration through the 

 walls of the pulmonary air-cells and the plexus of capillaries dis- 

 tributed upon them. 



It was said that all gases were not equally transmissible. The 

 experiments of Professor Mitchell have demonstrated this fact : and 

 the following list shows their comparative transmissibility, beginning 

 with the most powerful : Aonmonia, sulinhiireited hydroge7i, cyano- 

 gen, carbonic acid, nitrous oxide, arsenuretted hydrogen, olejiant 

 gas^ hydrogen, oxygen, carbonic acid, and nitrogen. 



The experiments of Brunner and Valentin have led to the inte- 

 resting result, that when two gases are placed on opposite sides of an 

 animal membrane, the relative proportions absorbed and exhaled, 

 will be inversely as the square roots of their specific gravities. Thus, 

 if we have oxygen on one side, and carbonic acid on the other of 

 an animal membrane, the volume of o5fygen that passes inwards 

 will exceed that of the carbonic acid that passes outwards, in the 

 proportion of 1174 to 1000. The application of this to respiration 

 is easy. 



Endosmose does not explain all the phenomena of absorption, but 



