38 CHARLES F. W. McCLURE 



VII. ON THE NATURE OF THE FOECE WHICH MAY DRIVE WATER 

 THROUGH THE SKIN IN A DIRECTION COUNTER TO THAT CAUSED 

 BY OSMOTIC PRESSURE 



We have shown in the preceding pages that a number of 

 factors may be concerned in the transport of water through 

 the skin in the living frog, as well as through the skin when 

 detached from the body. These factors include osmotic pres- 

 sure, the capacity of the skin itself to absorb and to lose 

 water, and a force which acts simultaneously and in conjunc- 

 tion with osmotic pressure, though independently of this. 

 Having demonstrated the role played by each of these factors 

 when acting either independently or in conjunction with one 

 another, we must now analyze more closely the nature of 

 the force which is able to drive water through the skin in a 

 direction opposite to that of osmotic pressure. 



In 1918, Gunzberg 8 published a paper dealing with the 

 pathology of oedema, in which he advanced the view that 

 the older theories of nitration, osmosis, and the affinity of 

 colloids for water, do not afford an adequate explanation of 

 oedema, and that the passage of water into the intercellular 

 spaces is due to the electrical properties of the membrane 

 separating circulating fluids from the tissues. He stated 

 that the E. M. F. is due to membrane polarization; that the 

 element K and the ions H and OH play an important role in 

 this electrical osmosis, which is able to drive the fluid in a 

 direction opposite to that of osmotic pressure. Gunzberg 's 

 view was based on experiments made on pithed frogs which 

 were perfused with Ringer's solution and modifications of 

 this solution; in these experiments the fluid entered by a 

 canula in the aorta and left by the proximal end of this 

 vessel. Gunzberg found that careful perfusion with a 0.7 

 per cent NaCl or with Ringer's solution caused no oedema. 

 When, however, the Ringer's solution was deprived of K, 

 there resulted a characteristic oedema in which the final 

 weight showed as much as a 40 per cent increase in the 



8 Gunzberg, I. 1918 Contribution a 1 'etude de pathogenie de 1 'oedeme. 

 Archiv. neer. de Physio!., vol. 2. 



