Physiological Studies on Schistostega osmundacea. 



15 



to be 0.006 — 0.002 for the growth of the protonemata, and 0.01 — 

 0.004 for that of the shoot. (Table IV.) 



Table IV. 

 Intensity of Ijight and relative " Lichtgenuss." 



From the above experiments, I have come to the conclusion 

 that the optimum Intensity of light for the development of the moss is 

 0,02 — 0.002 ; that the protonema can grow in a light even as feeble 

 as 0.0008 ; that the shoot ceasc's to grow lohere the intensity is 

 0.001, and that the i^equired minimum ''Lichtgenuss'' of the moss 



is about —-—■ . 

 500 



2. Effect of Light on the Moss.— When the filaments of 

 the protonemata, after growing over the surface of the soil or any 

 other object on which the moss grows, send new filaments up into 

 the air, they are easily acted on by light, curving towards the 

 direction from which it comos. These growing filaments possess a 

 positive heliotropism. Their orientation may be changed by turning 

 the culturing dish 180 degrees. The full-grown filaments are not 

 bent in the new direction of light, but new branches are given 

 out from each filament in the direction of the light. (Fig. 19.) 

 The growing shoots, too, have been observed to possess a positive 

 heUotropism. During my experiments, I turned a culturing dish 

 180 degrees on the 4th of April, and found on May 13th that tlie 



