778 H. E. KNowLTon 
The results of these experiments again show the favorable effects of 
fairly low temperatures. A freezing temperature, however, seems to be 
injurious, and in this respect corn pollen differs from pollen of most species. 
When corn pollen does not adhere, high humidity seems to prolong its 
fertilizing power. 
Only two storage experiments were conducted in 1917; owing to war 
conditions. The pollen was stored in watch glasses, over different per- 
centages of sulfuric acid. Novy jars were used. The pollinations were 
made as in 1916. The results are given in table 22: 
TABLE 22. Corn Potten StoreD at 6°-10° C. uNpER Humripitries oF 50 
Per Cent anv 80 Per Cent. 1917 
Ears pollinated Fertilization 
Length of st 
CERES eee 50 80 50 80 
per cent per cent per cent per cent 
humidity | humidity | humidity | humidity 
Hours 
(CHORES Ae tee ts MRC Set EST re iche ee Magi cert 4 Coote me Ur et 1 - 85 45 
TIC) Seger iaateciest 2 Boo esac al Aedes eC Co ae ants letter 3) 3 48 20 
OMA Hert eg poe te tient) 1. Rene ete tee Bre SR NY SO LL OHM 2 2; 75 52 
2 (i) apo ence eae Mise PNR Note dae Se ty. VEY SeedPeer p 33 3 62 62 
AG WER aaa teaser che yh My oie hee cae te (ME ae ees 6y.0.5 || 34 
EYAL hea Salo Red St hoa Cs oe hea eS eR I Re Oh 1. >) eee 60 
Cf las IM nS Rite, Sak lat tk MR ee, i ee Ne Sot lon ORAL 3 3 70 30 
Pollen produced in 1917 was more virile than that of previous years 
and it is to be regretted that more experiments could not be made. Con- 
trary to the results of the previous year, the lower humidity was the more 
favorable to longevity. 
In order that atmospheric conditions might be more easily controlled, 
corn plants were grown in the greenhouse in 1919. As a result, favorable 
and uniform temperatures were maintained both day and night during 
pollination time, which was a great aid in getting comparable results. 
As in previous seasons, actual fertilizing power was the only test of 
viability used. The method of storage of pollen was the same as in 1917. 
The results from these experiments (tables 23, 24, 25) are not very con- 
clusive, altho it can be seen that the pollen lived longer at the lower tem- 
peratures. The percentage of fertilization was smallest at the lowest 
