﻿GERMINATION AND GAMETOPHYTE OF FERNS. 



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intensity 0.02 had divided and formed prothallia of from 2 

 to 5 cells. The difference in the effect of light of the intensity 

 0.15 and 0.09 was very marked on November 14, when the 

 culture grown in the latter intensity was bright green, while 

 the surface of the culture grown in the more intense light 

 showed very little color. 



From these experiments it is readily seen that these fern 

 spores germinate most readily in a light intensity of from 

 0.075 to 0.09, and that both great and low intensities of light 

 are not as favorable for germination as medium intensity. 

 Of the fern spores used in this experimental work, none were 

 able to germinate upon leaf-mold in absence of light, neither 

 were they able to germinate in very weak light. 



Alsophila pruinata and Aneimia phyllitidis could not be 

 induced to germinate in leaf-mold in darkness at a tempera- 

 ture of 30°-33° C. This is contrary to the results of Heald, 

 who germinated a species of Alsophila and other ferns, among 

 them Ceratopteris thalictroides, at a temperature higher than 

 the ordinary laboratory temperature. 



Schulz was able to germinate Ceratopteris thalictroides in. 

 darkness at a higher temperature ; but was not able to secure 

 germination of the same species of Alsophila that Heald 

 worked upon. Neither was he able to germinate any other 

 species in darkness at a higher temperature. He thinks Ceror- 

 topteris is capable of germinating in darkness because it has a 

 water habit, such as the Marsiliaceae, which germinate in 

 darkness according to Arcangeli and Woronew. 



Laage, in some recent work upon germination, claims 

 higher temperatures have a retarding effect. 



The germination of Gymnogramme in 0.5% Knop's solution 

 is not exceptional, as Laage secured germination of a number 

 of ferns in both organic and inorganic solutions in absence 

 of light. In his valuable work he shows what strengths of 

 various solutions are most favorable for germination in dark- 

 ness. However he was not able to germinate Alsophila 

 australis, Asplenium lucidum, and Polypodium aureum under 

 any conditions in absence of light. 



According to the results of several investigators, the stimu- 

 lus to germination and to growth whicli in nature is given 



