770 
H. E. KNowitTon 
Pollen remained viable for four months in an atmosphere of carbon 
dioxide. 
occurred must have been anaerobic. 
that carbon dioxide has a retarding effect on both aerobic and anaerobic 
respiration. 
Influence of reduced pressure 
Kellerman (1915) found that Citrus pollen remained viable longer under - 
low atmospheric pressures. 
determine whether this was true also with Antirrhinum pollen. 
In this atmosphere, the small amounts of respiration that 
Kidd (1917), however, has shown 
Some experiments were made in 1917 to 
The 
pollen was stored in sealed glass tubes, with the atmospheric pressure 
reduced to 100 millimeters. 
TABLE 14. AntrrrainuM PoLLEN StTorAGE aT A Pressure oF 100 Minimeters Com- 
PARED TO STORAGE AT NORMAL ATMOSPHERIC PRESSURE, AT 0° C. 
1917 
Flowers Seed capsules Greatest Average length of 
pollinated developed germination pollen tubes 
Age laa 
In In In In In In 
normal | reduced! normal | reduced | nermal | reduced In normal In reduced 
+ pressure | pressure | pressure | pressure | pressure | pressure DSSS 1OHESSUES 
Days Number | Number| Number | Number | Per cent | Per cent 
hates 3 9 : 8 45 35 Short-long....| Medium-—long 
Beate tere alent ca ost be a Sn anaraee: 7 10 60 Medium-long.| Medium-—long 
AOA ates as 13 3 12 3 50 40 Medium-long.} Medium-long 
UU 3 2 3 2 70 15 Medium-—long.} Short-medium 
1 OD ittrestpe.srcesen ts ti) 6 2 5 60 0) Medium—longs| eerie ace 
te 7: ON eee Ao iMacuertens oe 60 0 Medium—lonsa|ieemerncecc a: 
161. Sipe lie soreeasttee Sie ites Zpashot SOs wlkrateraeds Short-medium.| ............ 
Under normal atmospheric pressure, pollen remained viable longer than 
Another series, at 10° C., gave 
under reduced atmospheric pressure. 
Dude (1903) also found this to be true with certain 
He attributed the lessening of longevity to the injurious 
similar results. 
kinds of seeds. 
products formed in anaerobic respiration. 
Influence of storage in pure oxygen 
Storage in oxygen was studied in 1917, with results as shown in 
table 15. The pollen was stored in sealed glass tubes. 
Due to the absence of the author during the war, no tests were made 
from the 196th day to the 670th day. Altho there was weak germination 
after the long storage, it is significant that there were no fertilizations. 
Undoubtedly, respiration was more active; perhaps, also, there was an 
