SOAPS, PROTEIN DERIVATIVES AND TISSUES 



239 



each of the series show that complete resolution of the original 

 heavy metal coagulum has 

 been obtained hi all cases. 



The importance of using 

 enough of the lighter metal 

 salts if reversion is to be ac- 

 complished is illustrated for 

 mercury coagulation in Fig. 

 113. With the exception of 

 the pure gelatin control, all 

 the tubes contained 5 cc. of 2 

 percent gelatin to which had 

 been added 5 cc. m/1000 mer- 

 curic chlorid. Twenty-four 

 hours later 5 cc. distilled water 

 were added to the pure gelatin 

 and a mercury gelatin control; 

 to the remaining tubes were 

 added 5 cc. of potassium iodid 

 of the concentrations m/1, 

 m/2, m/4, m/8 and m/32. 

 The photograph taken twenty- 

 four hours later shows complete 

 reversal of the coagulation only 

 for the tube to which m/1 

 potassium iodid was added and 

 less and less reversion as the 

 concentration of the reversing 

 salt was lowered. 



Lest it be thought that 

 these observations on " dead " 

 proteins do not apply to " liv- 

 ing " tissues the following < >1 >- 

 servations of KEHOE 1 may be 

 nf interest. The enzymatic 

 reactions are perhaps as charac- 

 teristic of living matter as any. 

 KMIOE finds that the stare hi- 

 spid tin^ activity of saliva may 



1 ROBERT A. KEHOE: Personal communication (1921). 



