A PHYSIOLOGICAL STUDY OF THE GERMINATION OF 
AVENA FATUA 
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 185 
W. M. Atwoop 
(WITH THIRTEEN FIGURES) 
I. Introductory 
The apparent inability of many seeds to germinate for some 
time subsequent to harvest has been the object of study both in 
Europe and in America. The vitalistic viewpoint, which early 
ascribed such phenomena to the inherent properties of protoplasm, 
obscured the whole situation. Such germinative delays were 
found capable of modification by external influences which were 
said to exert a stimulus on the seed. The later physiological 
studies have attempted to uncover the nature of the modifications 
in function which the so-called stimuli bring about. 
Many seeds with low germinative power after harvest acquire 
increased viability in succeeding weeks or months, during a perio 
which has been termed the after-ripening or germ-ripening period. 
The changes taking place during this period have been found, n 
general, due to alterations in the structures inclosing the seed, oF 
to modifications in the inclosed members themselves. The term 
after-ripening has been limited to changes of the latter type (22), 
but in this paper will be used to cover all changes in the seed 
subsequent to harvest, as a result of which greater germination 
percentages may be obtained. 
The most extensive investigations of germination characters 
among the Gramineae have probably centered on barley, an early 
and prompt germination of which is much sought in the malting 
industries. In agriculture much trouble is occasioned in the small 
grain regions by the persistence of the wild oat, Avena fatua L., 
and by the difficulty with which it is eliminated. As a cattle food 
it is undesirable because of the long and twisted awns, and also 
because of its lightness, averaging about 12-18 pounds per bushel. 
Laboratory and field tests have shown the seed to germinate very 
Botanical Gazette, vol. 57] . [38° 
