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show that under ordinary conditions of temperature and 

 food supply, the moss spores require a certain intensity of 

 light for germination , but that the required intensity is 

 not as great as in the case of the liverwort spores. These 

 facts were demonstrated for the three species of mosses 

 mentioned ahove. 



Reasoning from the results which I had already obtained 

 with fern spores, a series of experiments was carried out in 

 which cultures of spores were exposed to different tempera- 

 tures. The failure of the spores to germinate in the dark 

 is due as has already been stated to the fact that the con- 

 ditions of temperature, light, etc. were such that certain 

 cheraical processes necessar}^ for germination could not be 

 active. The results with fern spores show that heat is able 

 to effect this change as well as light, so that germination 

 may be called forth in complete darkness by subjecting the 

 spores to a higher degree of temperature than the normal 

 room temperature. That moss spores would be affected in 

 the same way as fern spores would seem quite probable, but 

 nevertheless my experiments in this direction have failed to 

 find any temperature at which moss spores will germinate 

 in complete darkness, when supplied with only inorganie 

 material. The temperature to which the general cultures 

 was exposed ranged from 19 — 21° C. Cultures were made 

 for the following degrees of temperature: 23°, 24°, 27°, 29°, 

 32° and 35° C and in each case in complete darkness. The 

 cultures at 35° C were kept for four days. At the end of 

 that time no signs of germination were visible, hence they 

 were removed to the light and at the ordinary temperature. 

 The failure of the spores to germinate under these conditions, 

 showed that they had been killed by the high temperature. 

 The other cultures were allowed to remain in dark for six 

 days and then removed to the light. The spores subjected 

 to 32° were not killed, but a very marked retardation of 

 germination occurred, since the period required for germination 

 was extended from three days to ten. The cultures that had 

 been kept at 29° also showed a retardation of germination, 



