Germination of the Seed of the Castor-oil Plant. 391 



The investigation of the three points discussed in the foregoing 

 portion of this paper has left unsolved another point of considerable 

 interest, to which my attention was drawn somewhat accidentally. 

 In examining the action of the glyceride ferment upon different 

 emulsions, some experiments were carried out with milk, and there 

 was then found to be present in the germinated seeds not only the 

 two ferments already described, but a third, which acts like rennet. 

 A tube containing 5 c.c. of milk and 2 c.c. of a glyceride extract of 

 germinating endosperms clotted in five minutes when exposed to a 

 temperature of 35 C., a control with the extract boiled remaining 

 unclotted for hours. At the same time a certain amount of acidity 

 was developed in the milk by the action of the glyoeride ferment, but 

 the action on the casein was not caused by this. A further experi- 

 ment was made to establish this conclusion. Two tubes were 

 prepared as before, and their contents coloured with litmus. As soon 

 as clotting had taken place in the one with unboiled extract, dilute 

 HC1 was added to the control till it was equally acid with the other, 

 but no clotting or precipitation took place. A further similar set of 

 tubes was prepared, their contents being made slightly alkaline, and 

 on exposure in the incubator the one with unboiled extract clotted, 

 while the control did not. 



This ferment, like the other, was by similar experiments shown to 

 be present in an antecedent or zymogen condition in the resting 

 endosperms, and to be capable of conversion in the same manner. 



This rennet ferment was found to be most easily extracted by 

 glycerine. 



The discussion of the meaning of the rennet ferment here, as in so 

 many plants, must be deferred, pending the completion of further 

 experiments now in progress. 



Summary. 



The work detailed above leads to the following conclusions : 



1. The reserve materials in the endosperm of Ricinus communis 

 consist of oil and proteid matters, the latter being a mixture of 

 globulin and albumose. 



2. The changes in germination are partly due to ferment action, 

 there being three ferments present in the germinating seed, one a 

 proteolytic one resembling trypsin ; the second a glyceride one, 

 splitting the oil into fatty acid and glycerine; the third a rennet 

 ferment. 



3. At least two of these, 'and therefore, presumably, all of them, 

 are in a zymogen condition in the resting seed, and become active in 

 consequence of the metabolic activity stirred up in the cells by the 

 conditions leading to germination, especially moisture and warmth. 



