193 MINNESOTA BOTANICAL STUDIES. 



and other previous investigators. On the other hand Chloro- 

 chytrium has well developed chlorophyll and lives near the sur- 

 face where abundant light is available. The requisite inorganic 

 matter may gain access to the cells by the constant or at least 

 periodical submersion in water. 



Chlorochytrium lemntz penetrates dead as well as living 

 leaves and culture methods demonstrate an entire lack of de- 

 pendence of the endophyte upon a host plant. In many endo- 

 phytes zoospores can be developed on culture slides for months. 

 No proof has as yet been adduced for any injury of the host 

 beyond the results of the mechanical pressure exerted. The 

 explanation then of endophytism is to be found not in parasitism 

 but in the mechanical protection of position, which the inter- 

 cellular spaces of the host offered ; hence the appropriateness 

 of the term " Raum Parasiten." It is, of course, possible for 

 parasitism to develop from such a condition and this develop- 

 ment seems to be in evident progress in such a nearly related 

 form as Phyttobium dimorphum and also perhaps in Nostoc 

 lichenoides. In the systematic relations of Chlorochytrium and 

 the nearly related genera, Klebs briefly points out the inter- 

 mediate position of Chlorochytrium and Endos-ph<Rra> between 

 the Protococcaceae and the Chytrideee, the isolated position of 

 Scotinosphara and the probable affinities of Phyllobiutn on 

 the one hand with Chlorochytrium and on the other with Bo- 

 try dium. 



Schaarschmidt, 1881, found zoospores of Chlorochytrium 

 in a Desmid culture in which the zoospores subsequently devel- 

 oped, confirming Kleb's view on the parasitism of the endo- 

 phyte. In 1883 Kjellman described the following species : 



Chlorochytrium inclusum Kjellman. "In the vegetative 

 stage spherical or subspherical, entirely included within the 

 nurse plant, with the formation of the zoospores becoming 

 slightly elongated, short-conical, flask-shaped, ovoid or ellip- 

 soidal, finally bare at the pointed apex, which penetrates the cor- 

 tical layer of the nurse plant and emitting the zoospores through 

 an ostiole which has been formed." This species is endophytic 

 upon Sarc&phyllis arctica^ mostly near the surface but some- 

 times in the middle of the host. It averages 80-100 mic., has 

 yellowish-green contents and a cell-wall which is thin and of 

 equal thickness. The chromatophore is thin and is spread along 

 the wall. With the elongation at the formation of zoospores 



