62 



THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES 



entering the other to form hypnospores, while the 

 empty sphere may remain as a companion cell." 

 (Text— figs. B. C.) Carpenter was uncertain of the 

 identity and relationships of his fungus. Nonethe- 

 less, he referred to it as a chytrid and frequently 

 compared it with Physoderma maydis. 



The second of these fungi was reported by Tehon 

 and Harris as inhabiting the xylem of a diseased 

 Moline elm from Wisconsin. It is very similar to 

 the species found by Carpenter, and they accord- 

 ingly named it Carpenierella Molinea. Its vegeta- 

 tive thallus may appear in two slightly different 

 forms, one elongate, attenuate and thread-like with 

 few to many enlargements (text-fig. D), the other 

 amorphic and amoebic in appearance (text-fig. E). 

 This vegetative phase occurs in wood parenchyma, 

 wood fiber, and ray cells but not in trachae. The 

 thallus may be confined to one cell or extend through 

 pits in the walls to adjoining cells (text-fig. F). The 

 thalli figured by Tehon and Harris are somewhat 

 suggestive of the pseudo-plasmodium of Labyrinth- 

 ula, but the bead-like enlargements are not as dis- 

 tinctively spindle-shaped and cellular as those of the 

 latter genus. No zoosporangia have been found in 

 C. Molinea, but the occurrence of zoospores is sug- 

 gested "by the presence in some host trachae of 

 numbers of minute, mononucleate, rounded plasmo- 

 dium-like bodies, some few of which seem to possess 

 a single polar cilium," according to Tehon and 

 Harris. They have not, however, observed motile 

 flagellate cells. 



The origin of the so-called male and female thalli 

 which are reported to fuse is not clear and certain, 

 but Tehon and Harris believed that the swollen ends 

 of strands of the thallus which project into the 

 trachae (text-fig. F) become detached and assume 

 a spherical shape. These spheres later become asso- 

 ciated in pairs, and as the staining reaction of one of 

 them increases in intensity the other sphere becomes 

 more hyaline and empty and decreases in size (text- 

 figs. G— L). This shrinkage was interpreted by 

 Tehon and Harris to mean that the protoplasm of 

 one sphere had flowed into the other, and they ac- 

 cordingly designated the two thalli as male and fe- 

 male. They reported that the fusing thalli are equal 

 in size, but text-fig. G shows clearly that the male 

 cell may be considerably larger than the female. The 

 mature resting spore or oospore is spherical, 10 p, 

 with dense opaque protoplasm and numerous refrac- 

 tive globules, smooth, thick-walled, and accom- 

 panied by a small hemispherical or lunate companion 

 cell (text-fig. M). Germination of these spores has 

 not been observed. 



Tehon and Harris regarded their fungus as a 

 chytrid but were not certain about its taxonomic 

 position. They believed that the character of the 

 thallus and the presence of a vesicle or companion 

 cell on the resting spore indicate relationships with 

 the Woroninaceae (interpreted in the sense of Min- 

 den) or the Olpidiaceae. They accordingly placed 

 C. Molinea and Carpenter's fungus in the latter 



family near Pseudol pidiopxis. This disposition is ob- 

 viously untenable because Pxeudolpidiopxix is syn- 

 onymous with Olpidiopxis and belongs in the Olpi- 

 diopsidaceae. Whether or not these fungi belong in 

 the last named family will not be certain until the 

 presence or absence of zoosporangia and zoospores 

 has been demonstrated. The method of resting spore 

 formation is nevertheless very similar to that of 

 many species of the Olpidiopsidaceae, while the 

 amoebic, plasmodium-like vegetative thallus sug- 

 gests some relationship to or a parallelism in devel- 

 opment with the Plasmodiophorales and the family 

 Woroninaceae as these groups have been interpreted 

 by the author. While the origin and phylogeny and 

 relationships of Carpenierella are not clear, it is 

 nevertheless a significant genus and serves to empha- 

 size again that there may be many more simple fungi 

 to be found, the discovery of which will doubtless 

 change many of our present-day concepts concern- 

 ing the Phycomycetes. 



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