12 



Art. 5.— Y. Totla; 



tlie farther end of the cave : L — 



1 



1 



28.3 357.1 • ^^^ording to 

 WiESNER (10), the relative " Lichtgenuss " in the hght and in the 

 shade is in most cases -^ , bnt in our caves, at the farther end of 



the latter as mentioned above, the maximum " Lichtgenuss " was 



1 . . 1 



-jY and the mmimum ^^^^ , and tlie optimum " Lichtgenuss " of 



tlie moss between -77- and -rr-— . 

 50 200 



The following experiments made in the laboratory of the 

 Botanical Institute show that the intensity of light given above is 

 just what the moss requires. 



1) On the 15th of September, 1914, I placed, in a dark room, 

 seven Petri dishes, «ach containing the moss, at 15 cm., 30 cm., 

 45 cm., &c. distance from a small window, and repeatedly observed 

 the intensity of light in every position. The following results 

 were obtained. (Table III., A.) 



Table III., A. 

 TutouHÎty of Light and relative '' Lielitgenus:^." 



