NOTES AND MEMORANDA. 



Sexual Reproduction in Lower Thallophytes. — A couple of 

 fresh instances of the diffusion of a differentiation of sexes 

 amongst the lower Thallophytes have lately been recorded — 

 one in a member of the Chlorophyllophycefe, another of the 

 Chytridiacese, which are of considerable interest. 



Polyphagus Euglence^ Nowakowski. 



Dr. Leon Nowakowski describes at considerable length his 

 observations on a Chytridiacean, not indeed new but of 

 which he has discovered the sexual reproduction. ^ After 

 giving a short resume of the observations previously made 

 on the parasites of the Euglense, he proceeds to recount 

 his own observations. The distinctions from the genera 

 Chytridium, A. Br., and Rhizidium, A. Br., presented by 

 the subject of his investigations, were so considerable that it 

 became necessary to found a new genus under the name of 

 Polyphagus, and he now calls the form Polyphagus Euglencs. 



The author begins his account with the organization of 

 this form. The zoospores, after the cessation of their move- 

 ments, germinate between the resting Euglense ; they are at 

 first minute globular cells, colourless, with a strongly refrac- 

 tive yellowish nucleus. They give off four cruciately posed 

 or several (5-6) extremely thin threads radiating around 

 (Fig. d). Each of these becomes more or less elongated until it 

 encounters a Euglena come to rest, whose skin it perforates, 

 penetrating into the green protoplasm ; inasmuch as it gradu- 

 ally absorbs this it now acts as a Jiaustorium (Fig. d, e). One 

 of the germ-threads, namely, that one which first penetrates a 

 Euglena, soon surpasses the others in thickness, assuming the 

 aspect of a tubular stem, the parasite thereby acquiring a 

 clavate figure (c, e). The body of the Polyphagus increases in 

 size, owing to the nutriment absorbed from the Euglena, whilst 

 the nucleus grows smaller and finally disappears, some oil- 

 drops and vacuoles taking its place. The rest of the haustoria 

 either remain filamentary or they may elongate and become 



^ Nowakowski : " Beitrag zur Kenntniss der Chytridiaceen," in Cohn's 

 ' Beitrage zur Biologie der Pflanzeu,' Bd. ii, Heft 2 (Dresden, 1876) p. 201, 

 t. viii, ix. 



