— 56 — 



same failure of germination in complete darkness. The spores 

 which were exposed to light germinated however with as 

 great readiness as in tue control experiment, where they 

 were exposed to ordinary conditions. 



It is known that certain substances like iron Chloride 

 and cobalt salts, when used in a Solution which is too dilute 

 to be poisonous , exercise an accelerating influence upon the 

 growth of fungi. These substances are non-nutritive and the 

 acceleration of growth is presumably due to a so-called cata- 

 lytic action. This fact suggested the possibility of calling 

 forth germination in the dark by means of such substances, 

 and to this end the following experiments were performed. 

 Spores of the species generally used were grown in diiferent 

 strengths of iron Chloride : 0.25°/ , 0.125°/ . In no case was 

 germination called fortli in the dark. In the 0.25 °/ Solution 

 the Bryum and Brachythecium spores germinated neither in 

 light nor darkness. In the 0.125°/ Solution however, the 

 spores germinated abundantly in the light. A series of ex- 

 periments was also carried out in which spores of Funaria 

 hygrometrica were supplied with a dilute Solution of cobalt 

 sulfate, C SO 4 . I have shown in my investigations with 

 seedlings 1 that cobalt Solutions are extremely poisonous; 

 hence in order to obtain solutions which would not have a 

 toxic action, a very great dilution of the stock Solution was 

 required. Sowings of the spores were made for both light 

 and darkness and supplied with ^ ^ 4^0, and -^ 

 gram-molecule solutions. In all of the cultures the spores 

 germinated in the light without any marked retardation, but 

 in the dark, the same as in previous experiments, no ger- 

 mination occurred. Thus all of the previous experiments point 

 to the fact that germination in the dark was due to the 

 nutritive value of the sugar and peptone and not to any 

 stimulating or catalytic action. 



It is also interesting to know the minimum amount of 

 sugar which will suffice to call fortli germination in the dark. 



1 Bot. Gaz. 22 : 143. 1896. 



