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MISSOURI BOTANICAL GARDEN. 



days. A sowing of the same species in leaf-mold at room 

 temperature did not germinate in darkness in 40 days. 



In very diffuse light of 0.002 intensity, the spore coats of 

 Alsophila pruinata burst, but germination went no further 

 during a period of six months. No change took place in D, 

 apiifolia in the same time, and no germination began in either 

 Aneimia phylUtidis or Asplenium ftlix foemina in three months. 



To determine the effect of different light intensities upon 

 length of time required for germination, Alsophila pruinata, 

 A. australis and Dicksonia apiifolia spores were used in the 

 experiments. 



Cultures in leaf-mold, of A. pruinata, were placed in different 

 intensities of light, and the time required for germination was 

 noted. Temperature and moisture were made as nearly 

 equal as possible in all the cultures. They were all in the 

 same green-house, exposed to a temperature varying from 

 18° to 24° C. In light intensity of 0.15, first division, which is 

 a definite point in germination and is used to designate germi- 

 nation in this paper, took place in 25 days. 



In light intensity of 0.075, division or germination began 

 in 12 days. In light of 0.02 intensity there was no germina- 

 tion in 25 days, in fact the spore coats were just bursting. 



Two series of Dicksonia apiifolia were grown. The first 

 was sowed on September 29, and examined on October 15, 

 On this date the spore coats of those in light 0.15, had just 

 begun to burst, while those in the weaker light of 0.075 in- 

 tensity had begun to germinate. 



The second series was sowed on November 24, and on De- 

 cember 15, after 11 days, the spores of the culture in hght 

 0.075 had divided, and some of them were well along in 

 germination. At the same time the spore coats of those in 

 light 0.15 had just begun to burst. The spore coats of those 

 in weaker light of intensity 0.02 did not burst until the 

 fifteenth day, while those in light 0.075 germinated in 8 days. 



A series of spores of Alsophila australis was sowed on Sep- 

 tember 27, and examined on October 24. The spores from 

 light intensity 0.15 had germinated and formed young pro- 

 thallia of from 2 to 3 cells. Those in light 0.09 had grown 

 into prothallia of from 5 to 12 cells, and those in light of the 



