702 AQUATIC PHYCOMYCETES 



definite, characteristic arrangement that it enables one to recognize free- 

 swimming spores of this genus, as well as those of Monoblepharella and 

 Gonapodya. When the spore is in motion the refractive granules in the 

 cytoplasm come to occupy the most distal portion of the now more 

 cylindrical spore body and, indeed, often appear to protrude from the 

 somewhat acuminate slightly quivering apex (Fig. 48 C, p. 700). Some- 

 times they seem to be fused into a single broadly conelike structure 

 ( Fig. 48 D-E). Immediately beneath them is a space entirely devoid of 

 granular material. A narrow band or strand connects the granules with 

 the rest of the spore body or possibly with the nucleus. The greater part 

 of the spore is of a very finely granular slightly refractive protoplasm, 

 which appears in some views to be a band the two ends of which have 

 fused (Fig. 48 E). At the point of insertion of the flagellum a highly 

 refractive body may usually be found. The little-known figures of zoo- 

 spores and antherozoids given by Cornu in van Tieghem's Traite de 

 Botanique indicate that he was well aware of this characteristic internal 

 structure. It is essentially like that observed in the swarmers of Blasto- 

 cladia, AUomyces, and such chytrids as Nowakowskiella and Clado- 

 chytrium, although Blastocladia and AUomyces lack the well-organized 

 nearly centric globule found in the other two genera. 



In Monoblepharella nonsexual and sexual reproductive organs may 

 occasionally be formed simultaneously on the same plant. Apparently, 

 as earlier indicated, this occurs when favorable temperatures for the 

 production of each overlap. The zoosporangia are ordinarily formed 

 at the periphery of the colony, at the tips of delicate, sparingly branched 

 hyphae. By subsequent sympodial branching of the hypha they appear 

 lateral. The difference in width of the sporangium and its attendant 

 hypha is so striking that the sporangia frequently resemble long 

 slender fusiform or siliquiform highly refractive conidia lying free in the 

 tangled mycelial complex. The zoospores are fully matured before 

 discharge, and emerge through a small pore formed upon the deliques- 

 cence of the sporangial apex, in the same manner as in species of 

 Monoblepharis. They are ovoid or somewhat cylindrical, and have a 

 single long posterior flagellum. The internal organization is exactly 

 like that in Monoblepharis. Secondary sporangia are produced by 

 sympodial branching. 



