CHYTRIDIALES 395 



MITOCHYTRIDIUM Dangeard 



Bull. Soc. Mycol. France, 27: 202. 1911 

 (Fig. 24 C, p. 396) 



Thallus endobiotic, eucarpic, monocentric, consisting of a broad, 

 cylindrical, and unbranched, branched, or irregularly lobate tube, the 

 rudiment of the zoosporangium, from which arise one or more delicate 

 axes which become divided distally into rhizoids, wall giving a cellulose 

 reaction with chloriodide of zinc; sporangium inoperculate, formed 

 from the tubular part of the thallus which is cut off by cross walls 

 from the rhizoids; zoospores posteriorly uniflagellate, with a single 

 globule, completely formed within the sporangium and escaping 

 successively to the outside by one or more short tubes which penetrate 

 the wall of the substratum; resting spore (?) endobiotic, with rhizoids, 

 apparently asexually formed, germination not observed. 



A monotypic genus, members of which are parasitic in desmids. 



The precise method of development is not known with absolute 

 certainty. The observations of Couch (1935c: 293) indicate that the 

 tubular part of the thallus — the rudiment of the future sporangium — is 

 laid down before the purely vegetative part, that is, the rhizoids, and 

 soon becomes separated from the more or less elongated penetration 

 tube. 



Both Dangeard and Couch state that thick-walled endobiotic resting 

 bodies are formed. These appear, in contrast to the monocentric 

 sporangial stage, to be polycentric in origin, several being produced on 

 a common rhizoidal system. If both investigators did not, in fact, have 

 a mixture of Mitochytridium and Catenaria (see Couch, op. cit., pi. 62, 

 fig. 9), this is an extraordinary condition, not found in any other of the 

 chytrids except Physoderma. 



The genus appears more nearly related to Entophlyctis than to any of 

 the Cladochytriaceae, where it is usually placed. 



Mitochytridium ramosum Dangeard 

 Bull. Soc. Mycol. France, 27: 202, fig. 1. 1911 

 Sporangium nearly isodiametric throughout, straight and unbranched 

 or branched, twisted, and bearing short lobulations, up to 660 [i in 



