420 Miss J. White. The Ferments and [Mar. 3,, 



germination capacity was entirely lost, but of the oldest specimens of maize 

 obtainable 60 per cent, of the seeds sowed germinated. 



Samples of the same seeds which had been tested for loss of germinating 

 power as described in the preceding section were first tested for the presence 

 of diastase ferments. 



1. Diastase. — The method adopted for the precipitation of the diastase was 

 the same as that described by Darwin and Acton in the ' Physiology of 

 Plants,' p. 305. Ten grammes of the seed were ground to a fine powder in 

 a hand coffee mill, and placed in a bottle containing 100 c.c. of slightly warm 

 distilled water, which was shaken for two hours with the aid of a water- 

 motor rocker. 



The mixture was then filtered and the filtrate concentrated at 50° 0. under 

 decreased pressure to about half its original volume. To the filtrate was 

 added enough 90-per-cent. alcohol to produce a white flocculent precipitate. 

 This precipitate was separated by filtration, and the filter-paper containing 

 the precipitate was placed in an exhausted desiccator over sulphuric acid 

 during the night. When dry, the precipitate was scraped off the filter-paper 

 by means of a sterilised knife, and dissolved in a small volume of cold, boiled 

 water. 



Equal quantities of this aqueous solution were put into each of three 

 test-tubes which had been previously sterilised, and the contents of one 

 tube C were thoroughly boiled, A very thin starch solution was prepared,, 

 and, when cool, equal quantities of the starch solution were added to each of 

 the test-tubes B and C and also to a fourth test-tube D. Of the four test-tubes 

 A, B, C, D, A contained only the original aqueous solution of the precipitate. 

 B contained about equal quantities of the aqueous solution of the precipitate- 

 and starch solution. C contained the same as B, with the exception that the 

 aqueous solution of the precipitate had been boiled and allowed to cool 

 before the addition of the starch solution. D contained only starch solution.. 

 The four test-tubes were placed in a bath at a constant temperature of 50° C. 

 After about one or one and a-half hours the test-tubes were removed from 

 the bath, and the contents of each were tested for the presence of reducing 

 sugar by means of Fehling's test. All through the experiments only 1 drop of 

 No. I Fehling was added to each test-tube and 2 drops of No. II. In every 

 instance, as may be observed from the detailed lists of experiments given 

 below, the presence of reducing sugar was detected in the contents of the- 

 test-tube B, while no sign of reduction was noted in the contents of any .of 

 the other test-tubes. 



The results of these experiments, which were performed with many varied: 

 specimens obtained from widely different sources, denote conclusively the 



