SAPROLEGNMA 57 



the former is ob\iously distinct from S. litoralis in the smaller number 

 and larger size of the eggs, in the simple, unhranched antheridial stalks, 

 in the fewer antheridia, in the al)sence of intercalary oogonia, in 

 the greater abundance of sporangia, and in the extremely distorted 

 gemmae. 



The present species can be readily recognized after the formation 

 of eggs In- the large number of oogonia with single eggs (usually over 

 50%); by the simple, unbranched antheridial stalks, and the antheridia 

 which applv themscKes to the oogonia by their ends instead of by their 

 sides. The above characters will serve in identifying the plant, but 

 the number of oogonia and even the number of oogonia with single eggs 

 varies considerably under different conditions of culture. These facts 

 will be brought out in the following general summary of results of ex- 

 periments. 



It has been found that the number of oogonia produced \aries inversely 

 with the number of sporangia produced. When cultures were made in 

 the ordinary way and left to grow for about fii\e days, only a fairly good 

 number of sporangia were formed while a very large number of oogonia 

 were produced, oogonia often being borne in clusters at the ends of 

 hyphae in addition to the usual number of racemose ones; on the other 

 hand when fresh water was added to the cultures sporangia were formed 

 on the ends of practically all the hyphae, the oogonia present being rac- 

 emosely borne. On grubs and termites the oogonial walls are unpitted, 

 but on bits of corn grain the walls of about 10 to 20% of the oogonia 

 show a few conspicuous pits. 



Quite often, especially when bacteria were present, clusters of gemmae 

 were formed on the ends of the threads, the gemmae resting until the 

 addition of fresh water. When the plant is culti\ated on termites the 

 threads are spirally twisted and the oogonia are mostly borne in elaborate 

 clusters on the ends of threads, about 75% of the oogonia containing 

 single eggs, the number in the rest of the oogonia being two, three or 

 four or very rarely more. On mushroom grubs the threads are usually 

 nearly straight and clusters of oogonia are rare, about 50% of the oogonia 

 containing single eggs. 



12. Saprolegnia parasitica n. sp. 



Plate is 



Growth rather delicate on insects and other usual media, moder- 

 ately dense, not long, rarely reaching i cm. on a mushroom grub. Gem- 

 mae abundant, size and shape very variable; often in chains, mostly 

 terminating hyphae, but sometimes intercalary. Sporangia variable, 

 but usually bent and irregular, at times up to 0.7 mm. long, very often 



