768 H. E. KNowLtTon 
TABLE 11. AntrrRHINUM PoLLEN Srorep at -18° To -30°C. 1915 
Sugar con- 
centration 
ape ee Seed Greatest | in which Average 
Age inated capsules | germina- | maximum length of 
De | developed tion germina- pollen tubes 
tion 
resulted 
Days Number Number | Percent | Per cent 
Fy) eae Ltt eat Ne ae ee 2 20 30 Short 
Lae Naito el el Suey Mich el 8 2 47 20 Short—long 
U1 OS New a cients lee ea ee 10 9 50 10 Short-long 
1 Ys Dt el ene te aa 6 4 35 25 Long 
CO BE ATA URE ae aes 6 0 12 25 Short-medium 
DST ATES PURE aN Vie tax 3 0' 36 15 Short-long 
ADT Mi see gh NOG IENY Ae pel ares 3 1 20 20 Short-medium 
SB ihr eee erent ah tome tate [hestcamyeat engin | Miler pi gett 26 BO aE eerily aso 
TABLE 12. Antrrrutnum PoLLEN Srorep at —18° to —30°C. 1917 
Flowers Flowers | Germina- Average 
Age fline tad lO reeaaieed an length of 
pollinate ertilize n allan Guibes 
Days Number | Number Per cent 
ARSE AL Rapala A iskltern Maen gar a 6 6 30 Long 
AST ale | SM eh top ce Ay PERS aN i REDE ce 8 5 50 Short—long 
AD ROO S ere an man Mae hag Mure eee uae 10 10 60 Medium-long 
LANE St PRC es ND REI eR ah oy BUREN 5 5 60 Medium-long 
LIC OS FS ie pet na) Ve ah RIN peg Oe 6 4 50 Short—long 
LISS} ee es Te Saat ey Le tA ae Ree ean PR 5 4 50 Short—long 
THUG eis cron te AN es EO Ra ee 5 3 50 Short-long 
TH SSO athe uc a a Seater Aceh ns Ph EgAS DAU Set RE NY angel RC se 15 Short—medium 
PAL AT RE sy Ral Bs Rete te Re aes eras ae WU Ut | UE oN ER 1 Short 
= 
In the 1917 experiment, pollen was still capable of fertilizing after 
storage for 161 days at —18° C. to —30° C. No other temperature 
experiments were performed that year. 
These results show an increasing longevity as the temperature at which 
pollen was stored decreased. At 40° C., only three fertilizations resulted 
and artificial germinations showed a weak pollen-tube growth. At 30° C. 
there were more fertilizations, but germination was poorer. Storage 
conditions were more favorable at 21° C. At this temperature, the pollen 
