376 Prof. J. R. Green. On the 



The ferment found, therefore, like the ferment in the pancreatic juice 

 of animals, is capable of decomposing fats into fatty acids and glycerine. 



The activity of this ferment, like that of so many others, was 

 found to be largely influenced by the reaction of the medium in 

 which it was caused to work. A set of experiments on this point is 

 subjoined : 



Five tubes, A E, were taken, and in each 5 c.c. of a ferment 

 extract, carefully neutralised, were set to work on 5 c.c. emulsion of 

 castor oil. They were made of different reactions, as under: 



A contained 0'066 per cent. HC1. 



B 0-133 



C 0-066 Na 2 C0 3 . 



D 0-66 



E was left neutral, as much water being added to it as was added to 

 each of the others with their respective acid or alkali. A I} B ls C x , Dj, Ej 

 were controls prepared like the others, but with boiled extract. 



After 3^ hours they were examined by the addition to each of 

 10 drops solution of litmus, when A and E became pinker than their 

 controls, B about equal to B^ C was less alkaline than C l5 but the 

 D set were relatively unchanged. Titration of the tubes with weak 

 alkali as before showed that the ferment works best in neutral solution, 

 is hindered by as little as 0'066 per cent, of HCl, and stopped by 0'133 

 per cent, of HCl. It is hindered by alkalis also, but works quite well in 

 them if the solution is weak, 0"066 per cent, of Na%CO s only retarding 

 the action slightly ; 0'66 per cent., however, stopped it entirely. 



Neither the 0'133 per cent. HCl nor the 0'66 per cent. Na 2 C0 3 de- 

 stroyed the ferment, for, on neutralising the four tubes, B, B 1? D, Dj, 

 and allowing them to stand in the incubator for several hours, action 

 began again in both the unboiled ones. The energy of the two was, 

 however, very different, for the acid liberated by the ferment in D 

 was live times the amount set free in B in the same time. The 

 activities of B, D, and E, tested during eighteen hours, are repre- 

 sented by the following figures : 



B. D. E. 



Exposed to 133 per Exposed to 0'66 per Kept neutral 



cent. HCl for 3| cent. Na 2 CO 3 for 3^ all the time, 

 hours, and then hours, and then 

 neutralised. neutralised. 



10. 50. 85. 



The ferment was by similar experiments found to be absent from 

 the resting seeds. Analogy with other ferments of both animal and 

 vegetable origin pointed to its probable existence here in the form of 

 a zymogen. To test this point, several experiments were made. 

 Some resting seeds were ground and treated with ether to extract 



