774 H. E. Knowiron 
TABLE 17. Invertase Activity oF ANTIRRHINUM POLLEN 
Invert Condition 
Age'of pollen sugar of pollen 
Days Milligrams 
(FSU ra NSER is Se ek aS lt a oe ea roe al ace att 189.7 Alive 
SO Nee ect restart aa ver tyreme cw sella BN Been FS nER aH REA Meare 195.6 Alive 
DATA U)Beteat sti a oe atecycmy aA Ge aa, con aes Ae aie eee CLE oS Wad Dead 
ESA V) ehie hath ANCOR Virsa SRI Oe ANA ek Aum S 0 a ORO! ot TEs Ee A PER eR er 15.8 Dead 
An increase in the proportion of reducing sugar as the age of the pollen 
increases is shown in table 16. There are several possible explanations 
of this. A decrease in respiration would tend to result in a surplus of 
reducing sugar, provided that invertase activity continued at the same 
rate. In other words, this respiratory material would not be used as 
rapidly as it would be formed. There may also be a readjustment in 
the cell protoplasm which would bring more of the enzymes in contact 
with the cane sugar. As metabolic activities proceed, this reorganization 
may very probably be taking place. 
This suggests the theory of Crocker and Groves (1915) that the death 
of seeds is caused by a coagulation of the proteins of the protoplast. An 
attempt was made to apply the temperature-time-of-coagulation formula 
to loss of viability of Antirrhinum pollen. Consistent results could not 
be obtained, probably because the moisture content of the pollen grains 
varied. However, it was found that Antirrhinum pollen can withstand 
high temperatures to a remarkable degree. 
The activity of catalase was very great in fresh pollen. There was 
some activity in dead pollen, but the decrease over that of fresh pollen 
was noticeable. 
Storage experiments with corn pollen 
Since the results of previous workers pointed to the beneficial effects 
of low moisture conditions on pollen longevity, experiments were made 
with this in mind, in 1915. Sweet corn was used, the variety being Golden 
Bantam. Corn pollen for each series was mixed thoroly and _ stored, 
in paper envelopes, in covered glass fruit jars. The pollen was divided 
into several envelopes, for convenience in withdrawing parts of it at 
the end of each interval. Each jar had several inches of anhydrous 
