ZYGOMYCETES 121 



suddenly shoots off the conidium by an arching back of the wall (Fig. 73, 

 2 and 3), which collapses, although uninjured. 



The conidiophores and zygospores are formed approximately at the 

 same time. Certain protrusions develop to thick hyphae whose tips 

 swell after contact (Fig. 73, 4). The smaller hypha discharges its 

 content into the larger which is surrounded by a double wall and becomes 

 the hypnospore (Fig. 73, 5). After a few days the zygospore may 

 germinate with one or more hyphae which generally begin to cut off 

 conidia after a short period (Fig. 73, 6). In Condiobolus mllosus, conidia 

 and asexual hypnospores were produced but no zygospores (Martin, 1925). 

 The cytological relations of this species have not yet been investigated, 

 but in the closely related Delacroixia coronata, on agarics and orchid seed, 

 the hyphal cells and conidia are multinucleate (Gallaud, 1905). 



The peculiar outgrowths of the mycelium of Conidiobolus also appear 

 in Completoria complens, parasitic on prothallia and young leaves of 

 several genera of ferns (Leitgeb, 1882). Because its parasitism is limited 

 to a few host cells, its thallus has undergone considerable degeneration, 

 so that in the Entomophthoraceae, Completoria occupies a place like that 

 of Lagenidium in the Oomycetes. The conidium germinates by a tube 

 which forms numerous protrusions within a host cell, and finally entirely 

 fills this cell which meanwhile has swollen to twice its original volume. 

 Where these protrusions touch the side wall, they penetrate the neigh- 

 boring cells where they develop to similar knobs. At the end of the 

 vegetative period, the protrusions develop to hyphae, each of which 

 pierces the cell walls and cuts off a conidium. The conidia are discharged 

 by the bursting of the conidiophore. With insufficient nourishment, e.g., in 

 young prothallia, the fungus proceeds to the formation of hypnospores. 

 The content of the group of tubes collects in one or more parts and is 

 surrounded with a thick wall of several layers. 



Entomophthora, parasitic on insects, lacks the mycelial protrusions and, 

 in contrast to Conidiobolus, increases by sprouting and division; here 

 the sprout mycelium is the only thallus. 



Entomophthora Muscae (Empusa Muscae) causes epidemics among 

 flies in the fall (Brefeld, 1884; Thaxter, 1888; Olive, 1906). The conidia 

 cling between the hairs of the upper surface of the body. They form a 

 germ tube which generally penetrates the interior through the breathing 

 pores or through the thinner membrane at the junction of the appendages 

 or the thinner parts of the integument on the lower side of the body. 

 Inside it develops into irregular, thick multinucleate fragments of 

 variable form and size, called hyphal bodies. These reproduce con- 

 tinually by sprouting and division and are distributed over the whole 

 body by the blood vessels. After 2 or 3 days, the flies are plugged by 

 fungi; they cling somewhere, often on window panes, and die. The 

 hyphal bodies germinate with one or more unbranched germ tubes which 



