56 THE SAPROLEGNIACEAE 



The following cultures were made from No. 3 of April 6, 1918: 

 On corn meal agar. Growth vigorous, covering agar plate; sporangia rare; gemmae pres- 

 ent in chains; fair number of oogonia produced; antheridia on every oogonium. 

 On boiled corn grain. Growth very vigorous; sporangia as normally produced; many 

 gemmae; a good many oogonia of normal shape and appearance. This culture was 

 repeated and it was observed that the gemmae became sporangia, emptying their 

 spores by a quite lengthened papilla upon change of conditions, such as pouring on 

 fresh water or transference from ice box to open. 

 Many other cultures were made, of course, on insects, grubs, flies, 

 etc., with results considered normal as described. 



II. Saprolegnia megasperma n. sp. 



Plate 17 



Mycelium on grubs and vegetable media about as vigorous as in 

 Saprolegnia ferax or S.litoralis; threads on mushroom grubs or termites, 

 9-351JI. thick, most about I5-20[j. thick, reaching a length of 0.5-0.7 cm.; 

 threads straight to wavy, usually wavy on termites. Sporangia abundant 

 on grubs, termites, and vegetable media, apical, 15-45 x 100-4001J., 

 variable in shape : the first ones usually long and distinctly swollen at the dis- 

 tal end, later ones usually smaller and more or less irregular in outline ; emp- 

 tying normally for the genus; renewed by internal proliferation or rarely by 

 cymose branching as mPythiopsis or Ach'lya. Not rarely in cultures slightly 

 infected with bacteria the sporangia may break away from the threads 

 as in Dictyuchus, such sporangia emptying normally after a long or short 

 rest. Spores diplanetic,biciliate, ii[j.thick when encysted. Gemmae abun- 

 dant, round to oval or very irregular, emptying upon the addition of 

 fresh water by one or more long papillae. Oogonia produced in fair 

 abundance, inversely in proportion to the number of sporangia and 

 gemmae, 40-1 00[j. thick, wall smooth (rarely with a papilla), not thick, 

 without pits or rarely with a few small ones; usually borne on short 

 racemose branches which in length are as a rule less than the diameter 

 of the oogonia; not rarely borne singly or in clusters of several on the 

 ends of main threads in cultures in which sporangia are sparingly pro- 

 duced. Eggs i-io, single in over 50% of the oogonia in most cultures 

 (not rarely running considerably above or below this per cent); 30- 

 52(1. thick, usually about 381J1 thick; subcentric (one row of oil droplets 

 on one side, two on the other), not filling the oogonia. Antheridia 

 present on all oogonia, applied by their ends, seldom by their sides; 

 antheridial walls thick, easily visible even in old cultures; antheridial 

 branches usually of androgynous origin but quite often diclinous, usually 

 simple and unbranched; antheridial tubes developed and easily visible. 



Found near Wilmington, N. C, on December 30, 1921, in water, 

 trash and a little green algae collected from a branch by the old Atlantic 

 Coast Line Railroad bed. 



In its general habit the above species might be confused on hasty 

 study with 5'. litoraUs, which also was found near Wilmington. But 



