CHYTRIDIALES 245 



land; pine pollen, Gaertner (1954b: 21), Egypt, Northwest Africa, 

 West Africa, Equatorial East Africa, South Africa; Gaertner 

 (op. cit., p. 40), Sweden. 



As previously pointed out (Sparrow, 1936a), this species has appar- 

 ently been misinterpreted. Braun did not observe the rhizoids (al- 

 though Rabenhorst [he. cit.] states that they are present), but he gave 

 careful figures of the sporangia and zoospores. 



The sporangia differ little from those of Rhizophydium globosum. 

 Their angularity becomes evident only when the prominent discharge 

 papillae are formed. 



No figures or description are given of Schenk's fungus. Dangeard 

 (1884-85a: 88; 1886a: 294, pi. 13, figs. 1-5) described and illustrated 

 a form which differs from Braun's in several important features. 

 The sporangium is obpyriform or casklike rather than globose, and 

 at maturity it is somewhat angular because of the formation of several 

 papillae. The rhizoid is broad and tubular, unbranched, and extends 

 through a number of cells of the host, becoming somewhat constricted 

 in passing through the transverse cell walls. Subsequent investigators 

 of the chytrids have interpreted Braun's species as modified by Dan- 

 geard (de Wildeman, 1890: 17, fig. 5; Minden, 1915: 323, fig. 14a-b; 

 Sparrow, 1936a: 439, pi. 17, figs. 1-2). It is surprising, as Minden 

 has pointed out, that Braun did not observe the very broad and ex- 

 tensive rhizoid if it was actually present in his material. In view of the 

 fact that it has been shown (Sparrow, he. cit.) that there exists a para- 

 site of Oscillatoria with spherical sporangia (angular at maturity) and 

 a very delicate rhizoidal system, it seems more logical to suppose that 

 this was the type observed by Braun, not the form with broad tubular 

 "mycelium." The latter has been termed Rhizophydium megarrhizum 

 (see below). 



Fischer (1892: 90) thinks that the fungus found by Schenk on As- 

 pidium spores may be referable to Rhizophydium sphaerotheca rather 

 than to the present species. Although this is probable, there seems 

 to be no reason, other than similarity of substratum, for this conjecture. 



