410 AQUATIC PHYCOMYCETES 



of it was built upon the earlier observations and figures of Nowakowski 

 (1876a). Nowakowski identified with Braun's fungus a form having a 

 rounded or somewhat elongate sporangium with a conspicuous prolon- 

 gation terminating in a papilla. Its sporangium (up to three times as 

 long as broad) rested at somewhat of an angle on the expanded upper 

 part of a main rhizoidal axis which branched distally. After zoospore 

 discharge the delicate sporangium wall soon collapsed and disintegrated, 

 and the upper expanded part of the rhizoidal axis became converted 

 into a second sporangium, cut off by a cross wall, in basipetalous 

 fashion. Resting spores found in autumn were considered by him to 

 belong to the sporangial stage. Some of them were ellipsoidal and had 

 their outer wall densely covered with long hairs; at germination these 

 functioned as prosporangia. Others, however (also figured in the 

 process of germination), were completely smooth. 



Braun's descriptions of his species (1856b, 1856c), even though not 

 clear and lacking illustration, indicate that his fungus had a main rhizoidal 

 axis distally divided into rhizoids and proximally expanded, and that from 

 the upper end of this axis, which was sometimes provided with rhizoids, 

 a lateral saclike elongated sporangium protruded. The fertile part was 

 nearly equal in size to the upper expanded part and produced typical 

 chytridiaceous zoospores. Sometimes, instead of such a zoosporangium, 

 a smaller, spherical, brownish resting spore, with its outer wall covered 

 with thick protuberances or spines (but not hairs), was produced. 

 Nowakowski's fungus, therefore, differs in several features from Braun's. 

 It does not have the sporangium strongly lateral in position or form 

 new sporangia in basipetalous succession, and it has ovate or spherical 

 resting spores whose outer walls are either covered with hairs or are 

 smooth. 



Karling (1944c) identified the sporangial stage of a Rhizidiwn that 

 he collected, with Nowakowski's fungus. Emphasizing the differences 

 in resting-spore characters between Braun's and Nowakowski's fungi, 

 he combined his sporangial stage with Nowakowski's hairy type of 

 resting spore (only seen by Nowakowski), and segregated them under 

 a new binomial, Rhizidiwn nowakowskii. While he is correct in this, 

 because of the differences in resting-spore features, Karling leaves 

 unanswered the question of the proper disposition of the smooth- 



