rhyfeiologic.il Studies on Fchistostega osmumlncc u. 13 



In the Petei dish, placed at 15 cm. from the window, the 

 moss began to show its emerald green light in one week, and its 

 protonemata increased greatly in number dm^ing one month. At 

 30 cm. distance, the growth of the protonemata was even better. 

 But at 45 cm., though the moss thro^'e well at the beginning of 

 November, it gradually ceased to develop as the days went on, 

 hardly any growth being observable in the months of December 

 and January, and no emerald green light being then seen. The 

 light was observed to reappear at the beginning of April. The 

 moss in the Petei dishes placed farther back ceased altogether 

 to grow. When they were brought to 30 cm. distance from the 



window, however, the moss began to develop actively and to send 



1 1 



out a reflected light, L for this distance bemg -.^p ,, ^ f,,, . . 



=' ° 108.9 190.0 



From these experiments, it foUows that 0.01 — 0.002 is the proper 

 intensity of light for the growth of the protonema, and that no 

 growth is possible when it is below 0.000 5. 



2) By the culture of the moss in the Petri dish (page 10), 

 I observed the different degrees of the intensity of light in the 

 three boxes, and noticed 0.0069 — 0.0008 as the most suitable for 

 the development of the moss. The " Lichtgenuss " of the moss in 



these boxes was ^—7— .,^. ,. . (Table III., B.) 

 81.3 384.0 ^ ^ 



