1915] DE VRIES—OENOTHERA BIENNIS 193 
Before compressing the air in the seeds, these are thoroughly 
soaked with water.’ Ordinarily they are exposed in small tubes, 
half filled with water, to a temperature of about 30° C. during one 
night. In the autoclave they remain from one to three days, at 
the temperature of the room. My apparatus can accommodate 
over 100 tubes at a time, each containing a different sample. After 
leaving the reservoir, the seeds may be sown in seed pans for 
cultivation or may be left to germinate in the same tubes, if it is 
only intended to determine the proportion of seedlings produced. 
In order to do this the water is poured off through a small sieve, 
the tube is closed by means of a cork, and the seeds are distributed 
along the upper inner side of the tube, this lying horizontally. 
In this way they get exactly the required amount of water and of 
air for a vigorous germination. 
I will now give some figures to show the effect of this pump- 
ing in of air into the previously soaked seeds. After pumping, 
the degree of germination was determined by leaving the tubes 
in a stove at 30° C. and counting the seedlings in samples of about 
200 seeds each. Out of 18 capsules from self-fertilized flowers of 
a spike of O. Lamarckiana, 3400 seeds were counted, a separate 
germinating tube being used for the contents of each fruit. Of 
_ these seeds, 15 per cent germinated during the first two days and 
only 3 per cent during the two following days, showing the normal 
germination power to be almost exhausted. Then the seeds 
remained three days in water under a pressure of 8 atmospheres, 
after which they were brought back to the stove. The next two 
days produced 22 per cent seedlings, and the four following ones 
added only 1 per cent to this number. Then the remaining seeds 
were tried with aneedle. Only about 5 per cent contained 
embryos, half of which at least were evidently in a decaying 
condition. 
The total of germs was 46 per cent, leaving 54 per cent for those 
with an undeveloped germ. From these figures we see that the 
production of seedlings from a sample of seeds may be more than 
doubled by the pumping method, while all or almost all the healthy 
germs may be made to germinate. Numerous similar instances 
could be added. 
