30 CHARLES F. W. McCLTJRE 



forces by which water is driven inward or outward through 

 the integument. 



In experiment 506 (fig. 11) the temporary loss in weight 

 of the glove between the third and the fourth hour is appar- 

 ently due to a temporary loss of water by the skin itself. 



2. The behavior of gloves of frog's skin filled with a Ringer's 

 solution containing 6.25 grams of NaCl to 1000 cc. of H 2 0, 

 when suspended in a Ringer's solution containing 7 grams 

 of NaCl to 1000 cc. of H 2 



Controls: The behavior of skin gloves filled ivith a Ringer's 

 solution containing 7 grams of NaCl to 1000 cc. of H 2 0, when 

 suspended in the same solution 



A still greater difference exists in the three following than 

 in the last-mentioned experiments, between the osmotic pres- 

 sure of the Ringer solution that is contained in the glove and 

 that in which the glove is suspended. It will be observed 

 that the controls of these three experiments (509 A, 510 A, 

 and 511 A, fig. 12) gained in weight continuously from the 

 time the gloves were first suspended in Ringer, and that the 

 amount gained at the end of twenty-three hours' suspension 

 was greatest in the control 510 A and least in 511 A. In 

 experiment 510, of which 510 A is the control, the glove con- 

 taining hypotonic Ringer gained weight continuously for a 

 period of twenty-three hours and, except that the amount 

 gained was less, its behavior was similar to that of its con- 

 trol. The circumstance that the gain in weight of this glove 

 (510) containing hypotonic Ringer was continuous through- 

 out the experiment might be explained by the fact that this 

 particular skin may have possessed marked capacity to trans- 

 port water through itself in a direction opposite to the force 

 of osmotic pressure and at a rate which at all times exceeded 

 that at which water was driven by osmosis through the skin 

 outward. On the other hand, there is a marked difference 

 between the behavior of the two remaining gloves and that 

 observed in experiment 510 and in the three controls. In 

 both cases in which the glove containing hypotonic Ringer 



