436 BOTANICAL GAZETTE [JUNE 
laboratory, but in many cases no plants when sown in the field. 
Unpublished data obtained by EastHAm in Canada show that the 
germination of oats grown in the prairie provinces is often seriously 
reduced by early frosts. He says, ‘‘as far as our observations go, 
a couple of degrees of frost in the milk stage are in many instances 
sufficient to ruin oats for seed. In the dough stage they are not 
nearly so susceptible, and when well ripened and dry stand con- 
siderable frost without serious injury.’”’ EastHam found also 
that such seed, germinating poorly when harvested, often improved 
with age. This seems to indicate in such cases the necessity for 
a period of after-ripening. Through the courtesy of the Canadian 
seed laboratory and two American seed houses the author has had 
the privilege of testing several samples of frosted oats. The 
results are summarized in table VII. 
TABLE. VII 
GERMINATION OF OATS 
HULLs REMOVED; ON COTTON IN PETRI DISHES 
UNTREATED; |e $ oO AT 22°C. : 
r ON FILTER beara s° ON FILTER 
VARIETY | paper aT TEST PAPER AT 
20° C. -20° 0° 80 per cent | 6o per cent | 40 per cent | 20 per cent 
oxygen oxygen oxygen oxygen 
Lincoln .| 85 40 i host Sek ia ee eee 
Swedish . re 40 re BREE Wee Or deinen Oe pach eka ipa! SaRearar as, Wyse Mane a oe 
4920 34 35 38 31 25 38 33 
5139. Pate tages Cia FS ea ENE) ORE ae tne Sear) een pars Craw 
3477. 56 Boe ey ee ep eee tue Semin pen aaa 
3974- 45 pe Siar, Nema ued ny nem | Sey Rumi ee a (Mage eM geara oF eee eo Le 
4048. 89 62 94 93 97 95 96 
5302. 16 PTE pee eine genie cre LS Alpe ae ee gee ae 
The best germination was obtained from hulled seeds in oxygen, 
though the results are more clear-cut for no. 4948 than for no. 
4920. No definite conclusions can be drawn as to what percent- 
age of oxygen is most effective. It is noteworthy that two samples, 
nos. 3477 and 4948, show much better germination, 23 and 27 per 
cent respectively, than they did when tested in the Canadian Seed 
Laboratory six months earlier. This agrees well with the state 
ment made above that frosted oats go through a process of after- 
ripening and improve in viability as they grow older. There is the 
same need of after-ripening in wild oats (Avena fatua), as has been 
