77 



tion of the spores and the development of the prothaUia of the 

 various species of the Polypodiaceae used. However, Knop's 

 and Prahtl's sokitions were on the whole the best suited, espe- 



FiG. I. ProthaUia and young sporophytes of Onoclea stnithiopteris from 

 various nutrient solution cultures. 



cially the latter as it did not seem favorable for the development 

 of algae. The formulas for making up these solutions are as 

 follows : 



I. Beijerinck's Solution. 



NH,N03 0.5 g. 



KH„P04 0.2 g. 



MgSOi 0.2 g. 



CaCL o. I g. 



FeCl;, trace. 



Distilled water looo c.c. 



