1914] ATWOOD—GERMINATION OF AVENA 391 
in the summers of 1912 and 1913.1 Comparisons have been made 
in many cases with the varieties of A. sativa: known as Lincoln, 
Swedish select, Kherson, and White Tartar. 
1. GERMINATION TESTS.—Germinative tests made through a 
considerable period showed for the wild oat seed tested the same 
progressive increase in percentage of germination which has been 
noted by other investigators for various grasses. From many tests 
made those given in table I are typical, A and B representing two 
varieties.” 
TAB 
WILD OATS HARVEST OF IQII 
SHELL COATS ON SHELL COATS OFF In som 
TESTED 
A B A B A B 
December... ...... 0.5 4:3 ° ees DEPRES y ib Tie sage 
penuaty. i 55: Sy 9g bert Yi ee ee 
a ee 200 6 GA be irse ees O45 oh cee 
MM x Goeth 6 ha oS Sle Pa cl ee 77 
ee i 60.0 26.0 81.0 BE ee leo 
WS. oc 37.0 30.0 93-9 79 96 63 
Germination tests were made in Petri dishes on moist absorbent 
cotton at a temperature of about 20° C. Soil tests were made in 
the greenhouse, even watering being accomplished by the porous 
clay cup method (34). As pointed out by ZapDE, the germination 
is much better with the shell coats removed. However, there is a 
rise in germination rate apparent through the after-ripening period 
by seeds from which they have been removed. The peculiarities 
of germination are thus not to be attributed to low vitality of the 
seed used, nor to exclusion effects of the shell coats. 
In meeting the problem of after-ripening, it is evident that 
changes must take place during this period either in the structures 
inclosing the embryo or in the inclosed members themselves. 
Tests were undertaken designed to furnish data on this situation. 
The seed coat of Avena fatua is formed by the combined cell layer 
* For these samples I am indebted to Dr. M. A. Brannon of Grand Forks, Mr. 
Ancus Mackay of Indian Head, and the Dominion Farm at Brandon. 
?The term “shell coat” is used in this fete to include the palea and hileon 
inclosing the seed as opposed to the true seed coa’ 
