ZYGOMYCETES 123 



(Thaxter, 1888). In E. Grylli, the hyphal bodies divide by a septum 

 into two daughter cells; hereupon the content of one passes over into the 

 content of the other (Fig. 75, 1 to 3) and this becomes a zygospore 

 (Thaxter, 1888). In this species azygospores may be formed instead 

 of zygospores; under favorable conditions the hyphal bodies put forth 

 a process which takes up the protoplasm together with the nuclei, is 

 abjointed and surrounded with a thick wall. The nuclei neither divide 

 nor fuse. Accordingly the azygospores develop entirely parthenogene- 

 tically (Riddle, 1907). 



The remaining species are distinguished by uninucleate conidia and 

 branching conidiophores, as E. sphaerosperma (E. radicans) on the 

 caterpillars of cabbage butterflies (Brefeld, 1881), E. Sciarae on the 

 larvae and imago of Sciara, a small species of fly (Olive, 1906), E. 

 geometralis on a moth (Riddle, 1907), E. americana on certain flies 

 (Riddle, 1907), E. Delpiniana (Cavara, 1899) on Polyete lardaria, etc. 

 The germ tube rapidly penetrates the host, especially the fat bodies, 

 branches, and forms a coenocytic mycelium with only a few septa (Fig. 

 76, 1). When the fat body is consumed and the hyphae have reached 

 the blood vessels, they divide (in some species, e.g. E. sphaerosperma) 

 into hyphal bodies which increase by sprouting and division. Under cer- 

 tain conditions these may be changed to gemmae by the thickening of their 

 walls. After approximately a week, the infected insects die. The whole 

 content, even to the tracheae and stomach contents, is used up and the 

 insects are changed into mummies (fungus pseudomorphs). Toward the 

 end of this time, in the species with undivided mycelium, e.g.,E. Delpiniana, 

 the number of septa increases considerably, and the hyphae are eventually 

 divided into cells with few nuclei. These (in other species corresponding 

 to the hyphal bodies) develop almost simultaneously to long tubes which 

 pierce the body wall on all sides. On the lower side of the insect they 

 change to rhizoids and attach the dead body to the substrate. On the 

 distal side they develop conidiophores and fork so much that the branches 

 form a palisade and surround the insect with a thick felt. Some of these 

 threads remain sterile and become setaceous, like the paraphyses of the 

 hymenium in the higher fungi. The others form at each end a young 

 conidium into which a nucleus (in E. Culicis 2) slips and which is finally 

 cut off by constriction. They swell by continual water absorption and 

 discharge the conidia for a considerable distance as the Piloboleae do 

 their sporangia. The thin- walled conidia retain their ability to ger- 

 minate for about 8 days; under unfavorable conditions each germ tube 

 ends with a secondary conidium. 



At the appearance of unsuitable growth conditions, hypnospores, 

 zygospores and azygospores are formed. In E. sphaerosperma, only 

 azygospores are known. As the season progresses the hyphal cells no 

 longer develop conidiophores but their content migrates into a pro- 



