IX THE POLYPODIACEAE 



367 



Pteridium and Woodsia were obtained from the wild botanical 

 gardens of Minneapolis, Minnesota, through the courtesy of Miss 

 Eloise Butler. The spores of Woodwardia were collected near 

 Ann Arbor, Michigan. 



Fig. 2. Branched prothallia of Onoclea sensibilis L., X 125. 



Cultures of these genera were made by sowing the spores on 

 distilled water and on soil. A series of cultures of Camptosorus, 

 Phegoptens, Pteridium, Onoclea, Scolopendrium, and Woodivardia 

 were made by sowing the spores on Knop's and Prantl's full 

 solutions and on certain modifications of these solutions. 



The formulas used in making up Knop's and Prantl's ('81) 

 nutrient solutions are as follows: 



Knop's Solution 



MgS04 0.25 g. 



Ca(N03)2 i.oog. 



K2HPO4 0.25 g. 



KCl 0.12 g. 



FeCh trace 



Prantl's Solution 



K2SO4 0.7 



NaCl 0.23 



CaS04 0.7 



MgS04 0.5 



Na3P04 0.5 



NH4NO3 solution, 0.064 per cent. 20 c.c 



The modifications employed were the following: 



