GERMINATION OF SEEDS. 593 



tion. Wernicke^ has examined the action of hot water on 

 various seeds that germinate slowly owing to thickness or 

 impenetrability of their integuments. Seeds of Acacia 

 molissima and Lathyrus sylvestris were kept in hot water 

 and then allowed to germinate. Of the controls 50 per 

 cent, germinated. The following table gives the results : — 



Observations of considerable interest on the action of 

 water, and of air saturated with water, at different tempera- 

 tures occur in a paper by Just (10); limitation of space 

 precludes more than indication. 



Resistance to tIiermo7netric extremes and desiccation. — 

 But little work has been done on the influence of intense 

 cold on the ' vitality ' of seeds. The earliest seems to have 

 been that of Edwards and Colin quoted by Wartmann 

 (11); seeds of cereals were subjected to a temperature 

 of - 40°C. for some minutes, produced through evapora- 

 tion of sulphur-dioxide in vacuo. Germination occurred as 

 in the controls. There is a serious objection to this experi- 

 ment, namely, that the duration of exposure was insufficient 

 to allow the seeds to reach the temperature quoted. 

 Wartmann (11) tested nine species; the seeds were 

 divided into three lots ; one served as a control, the second 

 was placed in a thin glass tube, that was hermetically sealed 

 and refrigerated for half an hour at — 57^0. in a bath of 

 suphur dioxide : the tube was finally plunged into a mixture 

 of snow and salt, where it remained fifteen days exposed to 

 the winter cold. The third lot was also enclosed in a glass- 

 tube and placed at first inside a metallic receiver, in which 

 was liquid carbon dioxide, that on solidification produced a 

 temperature of — 78^0. The tube was then covered with 

 paste of solid carbon-dioxide and sulphuric ether and placed 



1 Abst. Ann. Agron., 21, 1895, 544. 



