IN THE POLYPODIACEAE 367 
Pleridium and Woodsia were obtained from the wild botanical 
has of Minneapolis, Minnesota, through the courtesy of Miss 
oise Butler. The spores of Woodwardia were collected near 
Ann Arbor, Michigan. 
Fic. 2. Branched prothallia of Onoclea senstbilis 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, 
Phegopteris, Pteridium, Onoclea, Scolopendrium, and Woodwardia 
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 Prantl's Solution 
MeSOe iG ea 0.25 g- sn Pages as sre ee O.7 gf. 
Cat(NOns. fir cee 1.00 g. NMaET oi sees 0.23 g- 
RhPOG ee 0.25 g. Gr 2 ees Tae Fea rank 0.7 ge 
BRT oe ieee 0.12 g Mase. «is oss eee O5 g 
FeCh: 0a Se trace NasPO Gok cots ee ete 
0.5 8 
NH.NOs;solution, 0.064 per cent. 20 C.c. 
The modifications employed were the following: 
