STUDIES IN POLLEN, WITH SPECIAL REFERENCE TO LONGEVITY 783 
of 1-per-cent soluble starch. After twenty-four hours digestion at 30° C., 
the reducing sugar was determined. The results showed no decrease in 
amylase activity of pollen one week old below that of: fresh pollen. The 
amylastic activity of seven-months-old corn pollen showed a marked 
diminution. This has no significance, however, as corn pollen remains 
viable for only a few days. 
Catalase activity 
Catalase activity was also determined. The method of extraction 
was similar to that for amylase. The Bunzell (1914) apparatus, graduated 
to read positive pressures, was used. Determinations were made at 
25° C. The results (table 30) are the average of five determinations 
for each age of pollen. 
TABLE 30. Carauase Activiry oF Corn PoLLEN 
Reading Reading | Reading Reading 
Age of pollen after after | after after 
1 minute 2 minutes 3 minutes 4 minutes 
Hours Millimeters | Millimeters | Millimeters | Mullimeters 
GRO err ee Mo Soe 4.3 ml AG. 9. 
FBS 666 5 68 DOI OR Eee eee 3.6 7 6.9 7.6 
BS 6b cio, 6 os blo en eee ea 2.8 SRO 6.2 6.9 
NOGMERT RTT oe ladle bei euts 2.8 5.3 | 6.2 7.0 
As was expected, catalase activity seems to parallel respiratory activity, 
as was found by Appleman (1916) with the potato; but there is no indica- 
tion that it has any relation to viability. Dead pollen still shows some 
catalase activity. Calculated in grams of fresh substance, the catalase 
activity is much lower than in Antirrhinum pollen. 
From these experiments, the author must agree with Andronescu (1915) 
that the death of corn pollen is normally due to drying out, and not to 
exhaustion of stored food or to loss of enzymes. This is borne out by 
the results of the storage experiments, in which the high humidities pro- 
longed life. Nevertheless, the pollen can resist desiccation to a consider- 
able degree without impairing its viability. Even at high humidities, 
which lessened evaporation, the life of the pollen was not greatly 
prolonged. Some other factor, such as protein precipitation, may, there- 
fore, be operating. 
