396 BOTANICAL GAZETTE [MAY 
to be the case. The results obtained, however, were interesting 
in another way. In making these tests, 25 seeds with like control 
were soaked over night in distilled water in the ice chest, and then 
placed in inverted test tubes over mercury and kept in the dark at 
a quite evenly registered temperature of about 21° C. Seeds were 
allowed to remain about four hours, a period during which the 
oxygen content of the tube was found not to fall below 16 per cent. 
At the end of the period the gas was drawn off and analyzed for 
carbon dioxide and oxygen with a Bonnier and Mangin gas-appa- 
ratus in the customary manner. From this data the respiratory 
. cc : 
ratio 6, was computed. Tests were made for the seeds intact, 
2 
seared, and intact but in 93 per cent oxygen. Anaerobic respira- 
tion apparently did not increase in the three months (January 
to March 1913) during which these tests were being carried on. 
The point to these results, however, may be noted on taking the 
average of many determinations made under the three conditions 
given intable VI. | 
TABLE VI 
Ratio average 
Seeds intact in pure air............ o.800 
RO es a sk 0.649 
Seeds in 93 per cent oxygen........ 0.557 
It is interesting to note the decrease of the ratio as the seeds 
are seared, and an even greater decrease as they are subjected to 
increased oxygen concentrations. The results do not seem to be 
out of harmony with the conception of the seed coat acting as 
a restriction to oxygen entry. 
5. GERMINATIVE TESTS UNDER VARYING CONDITIONS OF OX¥- 
GEN.—If the coats should thus tend to exclude oxygen, we might 
suppose that seared seeds would be able to germinate in an atmos 
phere of reduced oxygen content as well as intact seeds in air; while 
intact seeds, it might be supposed, would be benefited in germ 
nation percentage if placed in an atmosphere of increased Oxy gen 
content. To test out these hypotheses, the seeds were placed on 
moist absorbent cotton in dishes on tripods, and covered by 4” 
