486 



AMERICAN JOURNAL OF BOTANY 



[Vol. 8, 



suspensions was taken. To each portion 15 cc. of fresh Fehling's solution 

 was added. The tubes were placed in a water bath and boiled an hour. 

 The solutions were then filtered on desiccator-dried, weighed filter paper, 

 and the copper precipitate was washed with hot water until free from the 

 excess of Fehling's solution. The filter papers were then dried first in an 

 oven and then in a desiccator and again weighed. The gain in weight 

 represents the amount of reducing sugar present. 

 The weights of the papers are shown in table 8. 



Table 8 



1st Weight 



2d Weight 



Gain 



Unground pollen 



Ground pollen 



Ground germinated pollen 



Boiled pollen 



Sugar solution only. ...... 



824 mg. 

 832 mg. 

 83I-5 mg. 

 843 mg- 

 828 mg. 



857.05 mg. 

 860.2 mg. 

 857 mg. 

 845-35 mg. 

 829.1 mg. 



33.05 mg. 

 28.2 mg. 

 25-5 mg. 



2-35 mg. 



1.1 mg. 



The gain in the unground pollen, which appears larger, is relatively 

 less because in this test the 300 mg. was all pollen, while the 300 mg. in 

 the other tests was partly powdered glass. From these figures and from 

 several similar tests it seemed evident that in the case of Easter lily pollen 

 invertase, at least, there was no advantage in previously germinating the 

 pollen grains. Repetition of this type of experiment might show a wide 

 range of variation both for kinds of pollen and for their enzymes. 



The data obtained in testing for pectinase in Easter lily pollen confirmed 

 the opinion that for this kind of pollen there was no gain in pectinase as a 

 result of germination. 



Tests for Amylase 



The method used was to test a known quantity of starch paste with 

 active pollen and an equal quantity with boiled pollen for a control. First, 

 10 cc. of 1 percent starch paste was used with 150 mg. of pollen. Later, 

 5 drops of 1 percent starch in 10 cc. of water was found to be a better dilu- 

 tion. Toluol was used as an antiseptic. The tubes were allowed to stand 

 in a warm room for 24 hours and were shaken occasionally. Two portions 

 of 15 drops each were then taken from each tube, and to one was added 2 

 drops of iodine to see if the starch had disappeared, and the other was 

 heated with 15 drops of Fehling's solution to see if sugar had appeared. 

 The results are seen in table 9. 



In these tests, as in those already mentioned, the ground pollen was 

 more active than the unground, but the germinated pollen did not appear 

 to be more active than the ungerminated. 



From table 10 it is seen that all kinds of pollen tested contained an 

 amylase, but that this amylase was less active in the apple pollen (Siberian 

 crab) and in that of the magnolia (cucumber tree) than in the other kinds. 



