408 : BOTANICAL GAZETTE [May 
Comparing the degree of acidity of the various samples with the 
moisture contained in the respective embryos, the relations 
appearing in table VIII are found. 
TABLE VII 
EMBRYO ACIDITY COMPARISONS OF AVENA FATUA AND A. SATIVA 
TESTED AUGUST I912 
N/20 ALKALI FOR I GM. 
DRY WEIGHT 
Kind Season grown 
‘Tame (Swedish select). 2... «5... 05. ceeees IQII 3-79 
Tame (Swedish select) tested fresh....... IQI2 2.51 
Tame RUG Oe ee oe oe ee ees IQII S231 
Wor (indie Head) 6 a ee IgIt 2.37 
Wild (grown Chicago) tested fresh ....... 1912 1.87 
It is seen that there is a general tendency for the water-holding 
power and the acidity to rise contemporaneously. This situation 
was noted by Miss EcKerson for Crataegus. It is possible that 
such embryonic changes in A. fatua may be causally related to 
alterations in inclosing structures. Further investigation of the 
chemistry of the embryo is planned. 
TABLE VUI 
N/2o alkali to titrate 1 gm. dry weight = peat seg e 
Be ee ei ie ce 50.2 
Se eo oO ees 56.0 
Bo TA PAE Scr ea ue vets eine eee 54-3 
Bahk ee Fe ra es eS 71.0 
Oe ee ae ce 68.3 
8. ConcLusions.—The combined results, so far noted, namely, 
that germination can -be increased by various coat-breaking 
methods; that germination may at all stages be improved by 
increased oxygen; that when wounded or subjected to increased 
concentrations of oxygen there is an absolute increase in the rate 
of oxygen absorption; all seem to point to the conclusion ‘that 
oxygen supply is for the freshly harvested wild oat the limiting 
factor to germination, with the probability that coat restrictions to 
oxygen entry play a réle. The question still is open as to the nature 
of the physiological processes for which oxygen is thus essenue’ 
Griiss (31) believes that in the case of Phaseolus the abundant 
