1898.] Swan. — The Genus Leptoleg7iia. 31 



These chlamj^dospores, according to Breteldt, 1887, can 

 produce zoospores direct (which are liberated from a short 

 out-growing tube or from a simple opening), or they can 

 throw out an ordinary filament. 



Humphrey, however, draws a distinction by calling the 

 globular, direct zoospore-producing vessels " resting spor- 

 angia," whereas true chlamydospores produce their zoospores 

 in a distinct tube formed within an out-growing germ-hypha. 



The life-history of the individual species of the different 

 genera is fairl}^ constant under uniform conditions of favour- 

 able culture, but it is noticeable that the zoospores may be 

 induced to change their usual life-habits. Thus the diplanetic 

 zoospores of Saprolegnia will readily germinate without waiting 

 for a second period of activity, while monoplanetic zoospores 

 will occasionally even germinate within the sporangium. 



The genus Leptolegnia was founded by De Bary, on a single 

 species which he discovered in 1888 in a German mountain- 

 lake, and it appears to be rare, for its occurrence had not to 

 my knowledge been again noticed, until I lately found it at 

 Bandon, together with a new species of the same genus, which 

 I have called L. bandoniensis. 



The genera Leptolegnia and Saprolegnia are allied by their 

 diplanetic zoospores, and also b}^ the renewed development of 

 the zoospores taking place within the emptied zoosporangium, 

 otherwise the two species of Leptolegnia have a strong 

 morphological resemblance to the smaller and more delicate 

 genus Apha7i07nyces. 



The only description Qi Leptoleg7iia caudata, De Bary, which 

 I have seen is that contained in Rabenhorst's '' Kryptogamen- 

 flora" of Dr. A. Fischer, and although this agrees well enough 

 with the plant as found here to leave no doubt of its identity, 

 I have noticed differences worthy of mention. 



The very characteristic form of the oogonia described as 

 ** Schief-eiformig " is more noticeable in young than in matured 

 examples, the latter being irregularly globular, or when egg- 

 shaped, blunt, rather than sharp egg-shaped at the smaller 

 end, while practically spherical at the other. In a foot-note 

 (page 346) Dr. Fischer speaks of a plant which he kept in 

 cultivation for some time, and which, although agreeing with 

 De Bary's description of L. candata, yet failed to produce 

 sexual fruit. As my experience shows that L. candata .-gxo- 



A 2 



