SAPROLEGNIA 45 



oogonium with much larger ones. Aiiparently no antheridia. Repeated abo\e cul- 

 ture with same results. 



On yolk of egg. Growth abundant and extensive. A good many sporangia and a vast 

 number of oogonia formed. A very few oogonia (probably not more than i in loo) 

 had an antheridium attached. Antheridia androgynous or diclinous. No oogonia 

 inside sporangia, hence no cylindrical ones. 



On corn meal agar. The whole petri dish covered and within the agar a great number of 

 fine, healthy oogonia were formed, with perfect eggs of normal size. No antheridia. 

 A few small gemmae formed. This is our only Saprolegnia that forms oogonia in this 

 medium e.xcept 5. vwiwica and in that case many of the oogonia are inflated and with 

 no eggs. 



On corn meal egg yolk agar. Fine growth, covering agar. Very many oogonia, with fine 



eggs. Antheridia on not more than 5^ 



P7 



0- 



In the following cultures a .1% solution of the salts in distilled 

 water was used, and the food material is yolk of egg, unless otherwise 



indicated: 



In KNOj. Growth delicate, but healthy. IMany normal but small oogonia, about one- 

 third with diclinous anlheridial branches. A few sporangia formed. 



In KH-PG). Growth strong and healthy. Sporangia present, but scattering, their spores 

 emerging and dispersing slowly. Many normal oogonia, none cylindrical, the great 

 majority with one or more antheridial branches about them, which are nearly all dicli- 

 nous (not one in a hundred androgynous), no antheridia cut off from the branches. 



In NajHPO.. Many sporangia, and very many normal oogonia, nearly all (at least 98%) 

 with antheridial branches, of diclinous origin; occasionally an antheridium was cut off. 



In K:SO(. Growth strong and healthy. Sporangia few, emptying as usual. Oogonia 

 very abundant, with normal and good eggs. In the main mass of the culture there 

 were anlheridial threads on at least 90% of the oogonia, a good many with antheridia 

 cut off. No gemmae. 



In Caj(PO.)!. Growth strong and vigorous. A good many sporangia. Very abundant 

 oogonia, maturing all eggs. Those in bulk of culture with 95% or more furnished with 

 antheridia; on margin a much smaller proportion have antheridia. Scattering gemmae. 



In Ca(NO))j. Growth more delicate than in others of this series, but about same extent. 



Oogonia much fewer than in preceding, all with good eggs. Even in the denser mass 



of culture not more than 10% with antheridia and very few with antheridia near the 



peiiphery. Many oogonia-like gemmae. 



The following experiments were made to test the vitality of the eggs : 



A culture on corn meal agar with fine oogonia and eggs was allowed to dry out to a sufficient 

 extent to collapse the gemmae. Water was put on and it was examined at intervals. 

 The eggs went to pieces soon. They had been killed by the desiccation. 



Eggs which had been resting for about four months were put in fly extract on September 

 13. 1912, in two watch glasses. One had a cover glass put over the eggs to exclude 

 air. Kept until September 24th. Neither showed germination though the eggs 

 seemed perfectly good. 



Experiments to test best method of preserving live cultures: 



Culture put in vial on corn meal agar, March 18, 1913, was found to be dead December I, 



19'.^- 

 Culture put in aquarium jar with algae in laboratory on March 3, 1913, was tested in 



jar on September 18, 1917, but no growth appeared. 



