1915] 



ROSE—DELA YED GERMINATION 



435 



this water was supplied, by long soaking or by forcible injection 

 under pressure, germination was much improved. 



Results for Finns aiistriaca are less conclusive on this point. 

 They do show, however, and the same is true for P. Strobus, that 

 soaking in either water or weak acid gave greater germination than 

 was obtained in the controls, 38 per cent and 13 per cent respec- 

 tively. For P. austriaca, better results were obtained from short 

 than from long soaking. 



Referring again to table IV, it is possible that the increases in 

 germination shown there were due not so much to the cold storage 

 in itself as to the thorough infiltration of the seeds with water. 

 There is need of much more work on this question before any 

 definite conclusions can be drawn. 



Exclusion of oxygen 



No attempt will be made to review former work, since this 

 has already been done by Shull (28). Results presented in table 

 VI seem to indicate that the germination of certain economic 

 seeds is delayed for lack of oxygen. They also indicate the need 

 of a detailed study of these seeds. 



TABLE VI 



Germination of seeds treated with oxygen or hydrogen peroxide 



Datura Wrightii was forced considerably by hydrogen peroxide, 

 Datura Golden Queen not at all. Lettuce gave good results, but, 

 as has been suggested, this is probably due to absorption of water. 



Effect of frost on seeds 



Atterberg (2) says that seeds of oats and barley harvested 

 in Sweden after a heavy frost gave fair to good germination in the 



