Classification. 141 



dung of frogs and lizards. All the species are 

 structurally closely allied, and, in the entomogenous 

 forms, are characterized by the thick hyphge filled with 

 oil globules and fatty contents, which emerge from 

 between the rings of the insect^s abdomen in compact 

 white masses of gonidiophores, producing at their tips 

 comparatively large gonidia, which at maturity are 

 projected to a distance. These gonidia, on coming in 

 contact with a new host, germinate at once, and 

 propagate the disease. In addition to the gonidial 

 mode of reproduction, thick- walled resting-spores, 

 either zygospores or azygospores, are often 

 produced, in some species in the tissues 

 of the host, in others externally ; these, after a 

 period of rest, germinate and produce gonidia 

 that are also discharged into the air by the sud- 

 den rupture of the supporting gonidiophores. In 

 some species the host is firmly attached to the 

 suhstratum, or substance upon which it rests, by 

 specialized hyphal branches, termed rhizoids by 

 Thaxter.^ These rhizoids may be simple or branched, 

 the tips being often discoid. In other cases the 

 affected host is firmly fixed by its proboscis to the 

 substratum. It was at one time considered that the 

 members of the present group were stages in the life- 

 cycle of the species of Saprolegniece. For example, 

 Empusa muscat was considered as a condition of 

 Saprolegiiia/erox, the cause of the salmon disease. 

 The discovery of sexually produced resting-spores in 

 the Entomojjhthorece has shown this view to be un- 



^ Entomophthorese of the United States ; Memoirs, Boston Soc. 

 Nat. Hist., vol. iv., number vi. (1888). 



