122 



LECTURES ON IMMUNITY 



after a certain time (/) is proportional to its square root. 

 Therefore at the time the distribution of alkali in the 



V2 



first tube is nearly the same as the distribution of alkali 

 in the second tube after the time /. This may be seen in 

 the height of the pink-coloured column of jelly which is 

 the same in the two cases. Experiments with the diffu- 

 sion of pepsin are of quite the same type. The indicator 

 is in this case not the reddening phenolphthalein, but the 

 liquefying solution of albumen. One measures the length 

 of the liquefied albumen-pillar at a given time. Therefore 

 Pawlow's and Borissow's experiments, which indicate that 

 the liquefaction of coagulated albumen or gelatin goes on 

 proportionally to the square root of time or of reacting 

 enzyme (pepsin, trypsin, etc.), are not conclusive in favour 

 of Schiitz's rule. 



A process which is very analogous to the digestion of 

 egg-white is that of the saponification of fats by means of 

 gastric juice or of extracts of gastric tissues (steapsin). 

 Volhard l used glycerine extracts of the pig's stomach and 

 observed that the quotient, q : V/= ^> of the digested 

 quantity q (in per cent), and the square root of the 

 concentration of steapsin, /, is nearly constant. This ob- 



1 Volhard ". Ztitschr.f. klin. Medicin, 42. 414, and 43. 397 (1901). 



