206 INJURY, RECOVERY, AND DEATH 



In the first of these methods" different solutions were 

 placed on opposite sides of a piece of tissue. The appa- 

 ratus used is shown in Fig. 89. The diffusion of salts 

 through the tissue was then measured. In the first 

 -. experiments, a solution of NaCl 0.52 M 



1 m ° was placed on one side, NaCl 0.26 M was 



^-l- 'JU * placed on the other: CaClz 0.28 M and 



0.14 M, as well as sea water and sea 

 water diluted with one volume of dis- 

 tilled water were employed in the same 

 way. As the stronger solution diffused 

 into the weaker the increase in the elec- 

 trical conductance of the latter was 

 measured. In Fig. 90, the rate of 

 change of the electrical conductance is 

 plotted against time. It will be observed 

 that NaCl diffuses through the tissue 

 Fig. 89 —Apparatus for more rapidly than sea water, while CaCL 



testing the rate of di£f- . 



at first diffuses more slowly than sea 

 water and then more rapidly: 



If dead tissue be substituted for 

 living, we find that the rate of diffusion 

 is very much more rapid in all cases, 

 and that all the solutions pass through 

 at about the same rate of speed. 

 These results are precisely what would be expected in 

 view of the results of the electrical experiments. 



In the second of these methods," tissues of the dande- 

 lion (Taraxacum offlcinale) were placed for a short time 

 in a salt solution and the rate at which salts subsequently 

 diffused out of the cell was measured by placing the 



' "0/. Brooks, S. C. (1917, B). 

 "Cf. Brooks, S. C. (1916, A). 



UBion of salts through 

 living tissue. It consists 

 of two glass cells A and B 

 (the former is provided 

 with a cover, (?) separat- 

 ed by a layer of living 

 tissue of Laminaria, E, 

 which is sealed to the 

 glass cells by a mixture 

 of vaseline and beeswax, 

 F. The lower cell is pro- 

 vided with a piece of 

 rubber tubing, C, and a 

 pinch cock, D. 



