i9i A DAVIS &• ROSE— AFTER-RIPENING 55 



Nos. 10, 20, 5, 3, and 7 were arranged to determine the relation 

 of oxygen to after-ripening. The seeds in these cultures were 

 placed on wet cotton in Novy jars of about a liter capacity. Nos. 

 10, 5, and 3 were without oxygen. The oxygen in no. 5 was removed 

 by pyrogallate. In nos. 10 and 3 the jars contained hydrogen 

 washed in pyrogallate. No. 20 contained hydrogen washed in 

 KOH and KMn04. The hydrogen used was from the Linde Air 

 Products Company of Buffalo, N.Y. Upon analysis it was found 

 to contain 2 per cent oxygen. The results with no oxygen or even 

 2 per cent were mainly negative. 



Several cultures were treated with ether in addition to the cold. 

 The seeds were placed in air-tight jars of a liter capacity. In each 

 jar there was a small bottle containing 10 cc. of water, to which 

 had been added ether varying in the different cultures from o. 25 cc. 

 to 1 cc. The jars were then placed in the cold from 8 to 16 days. 

 At the end of this period the seeds were removed from the jars, 

 placed in Petri dishes, and returned to the cold. The germination 

 in every case was less than that of the control culture without 

 ether. While ether may have a stimulating effect upon germinat- 

 ing seeds, the concentrations used here retarded rather than 

 hastened after-ripening. 



To determine the effect of a temperature upon after-ripening 

 somewhat higher than the ones previously employed, the following 

 cultures were placed in a water bath December i in which the 

 temperature at the beginning was q°-io° C. Tap water was used 

 in the bath and the temperature varied with the season, ranging 

 from the above temperature to as high as 2 2° C. in July and August. 

 The seeds were freed from the carpels. Table III shows the results 

 of these experiments. As fast as the seeds were after-ripened and 

 germinated, they were counted and removed from the bath. 



All these cultures were put in the water bath December 1, 

 excepting no. — 1, which was placed there 10 days later. This gave 

 it 10 days less exposure to the low temperature at the beginning, 

 and this in part, at least, may account for the difference in the 

 number of seeds germinated between it and no. 1. There is also 

 brought out in this table a very marked falling off in germination 

 as the temperature rose, which means, of course, a similar falling 



