ENDOSMOTTC EQUIVALENTS. 493 



liquids and causes them to pass through membranes, was 

 early pointed out by Dutrochet; 1 and the experiments of 

 Mialhe, to which we have already referred, have developed 

 the interesting fact, that while albumen attracts liquids 

 powerfully, it is not exosmotic. 2 The important applica- 

 tions of this fact to vascular absorption are evident. 



Some of the modifications in the endosmotic currents, 

 due apparently to very slight changes in the constitution of 

 the liquids, show an influence exerted by these conditions 

 which undoubtedly is capable of important applications to 

 physiological absorption ; but unfortunately, the ascertained 

 facts bearing upon the subject are few and imperfectly un- 

 derstood. Dutrochet observed that the presence of a very 

 small quantity of hydrosulphuric acid in a solution of gum 

 or of sugar diminished very considerably the endosmotic 

 action, by giving rise to a powerful exosmotic current from 

 the acid to the water. 3 A still more remarkable fact was 

 observed by Poiseuille. This observer filled an endosmom- 

 eter with a solution of chloride of potassium, immersed 

 it in serum, and noted quite a rapid elevation of the liquid 

 to the height of nine millimeters; but on substituting for 

 this a solution of the same density, to which the hydro- 

 chlorate of morphia had been added in the proportion of a 

 little more than one per cent., the liquid rose only to the 

 height of six millimeters, and there then followed a decided 

 exosmotic current. 4 



As we have seen that there are various conditions capable 

 of profoundly modifying physiological absorption, it will be 

 interesting and useful to compare them with the physical 

 and other conditions which influence endosmosis. In this 

 way we will be enabled to appreciate more fully the appli- 



1 DDTROCHET, De VEndosmose. Memoires, Paris, 1837, p. 46. 



3 See page 477. 



8 DUTROCHET, op. cit., p. 64. 



4 POISEUILLE, Rechcrches Experimentales sur les Medicaments. Comptes 

 Rendus, Paris, 1844, tome xix., p. 1000. 



