1909.] 



Latent Life of Resting Seeds. 



427 



Test for Erepsin. — Further investigations were carried on in order to find 

 out whether erepsin ferments were present in the resting grains. The mode 

 of precipitation of the enzyme has been previously described, the same 

 method being employed as was used in testing for pepsin. Before grinding, 

 the seeds were soaked for about five minutes in strong chloroform, as was 

 done when testing for the existence of fibrin-digesting ferments in the seeds. 

 One cubic centimetre of the aqueous solution of the precipitate produced by 

 the saturated ammonium sulphate was put into each of three sterilised test- 

 tubes A, B, and C. The same difficulties arose in the case of the samples of 

 prepared pancreatin as were met with in the diastase and pepsin, the 

 samples purchased giving the tryptophane reaction owing to the presence of 

 amide impurities. As in the case of the fibrin-digesting enzyme, the 

 contents of the test-tube C were boiled and allowed to cool. About 0*2 c.c. 

 of Witte peptone was added to each of the tubes B and C ; 5 drops of 

 chloroform were dropped into each of the three test-tubes, and the mouths 

 of the tubes were plugged with cotton wool. The three test-tubes were 

 placed in the oven, which was kept at a temperature of 35° to 36° C. 

 throughout the series of experiments. The test-tubes were left in the oven 

 for about three days, during which time they were occasionally shaken at 

 intervals. 



The test adopted for the detection of products of erepsin digestion such as 

 .amides was the tryptophane test. About 4 or 5 drops of bromine water 

 were added to each of the contents of the test-tubes A, B, and C, and without 

 exception tryptophane was produced in the contents of the tube B, whilst 

 no trace was observed in A or C. 



The results demonstrate the occurrence of an erepsin ferment in the 

 .seeds, which is destroyed in water at 100° C. Experiments were also 

 performed to determine the percentage of seeds capable of germination under 

 the action of a solution of commercial pancreatin in water. The results of 

 these experiments are stated in a special column of the tables below. 



As in every instance the tryptophane reaction was well marked, in order 

 to economise material the experiments for the detection of erepsin were limited 

 to one sample of fresh and one of old grains. 



The quantity of erepsin present must be fairly considerable as judged by 

 the degree of activity of the extract. 



Beference to the tables shows that no favourable effect oh the germina- 

 tive capacity of the seeds is noticeable as the result of soaking in 

 weak pancreatin solution. The addition of a weak solution of pancreatin 

 did not favour germination, but rather the reverse, except in the case of 

 4£-year-old rye. On repeating this latter test, however, the seeds only gave 



