— 55 — 



were placed in culture and supplied with a 0.5°/ Solution 

 of KN0 3 . The cultures in the light showed germination 

 alter the usual length of time, but no sign of germination 

 was observed in those which were deprived of light. Ex- 

 periments with the same results were also carried out for 

 the same speeies in a l°/ Solution of KN0 3 . De Vries 1 has 

 shown that the osmotic value of KN0 3 is about double that 

 of grape sugar with equal parts of the gram molecule, or 

 more exactly, the isotonic coefficient of grape sugar is 1.88. 

 The osmotic value of a 0.5°/„ Solution of KN0 3 , or approx- 

 imately a l , 5 gram molecule Solution, would be about the 

 same as that of a 2°/ grape sugar Solution, or a V 6 gram 

 molecule. The failure then of the spores to germinate under 

 the above conditions would tend to show that the osmotic 

 pressure within the spore could not have been the oper- 

 ative force in bringing about germination. 



The absence of any effect from osmotic pressure was 

 also rendered probable from the experiments in which the 

 spores were supplied with either glycerine or potassium 

 tartrate. Spores of the three speeies above mentioned ger- 

 min ated readily in one and two percent Solutions of glycerine 

 in the light, but in the dark they remained unchanged. 

 Glycerine is a non-nutritive substance for the moss-spores 

 and at the strength used would be about osmotically equiv- 

 alent to the sugar, In the l°/„ Solution of potassium tar- 

 trate , the spores germinated neither in the light nor dark, 

 but in the 0.5°/ Solution the growth was the same in the 

 light as in the control experiment. In the dark cultures 

 supplied with 0.5% potassium tartrate there was a complete 

 failure to germinate. The isotonic coefficient of potassium 

 tartrate is 3.99 2 and consequentl-y the osmotic value of the 

 last Solution would not be far from that of 2°/ grape sugar. 

 Cultures of spores which were supplied with a 2°/ Solution 

 of lactose, also non-nutritive for the moss spores, showed the 



1 Jahrbücher für Wissenschaft! Bot. 14 : 454. 1884. 



2 De Vries 1. c. p. 506. 



