292 THE LOWER FUNGI— PHYCOMYCETES 



Three other species have been referred in the hterature to 

 this genus. One, M. richteri Bresadola & Staritz (Staritz, 

 1892), was subsequently transferred to Empusa (Bubak, 1906: 

 105). The remaining two, M. cleoni Wize (1905: 716) and 

 M. starilzii Bresadola (1892: 133) are so imperfectly known that 

 their inclusion here must be regarded as merely tentative. 

 5. Empusa Cohn (1855: 301). 



syn. Entomophthora Fresenius (1856: 882). 

 Lamia Nowakowski p.p. (1884: 153). 

 Tarichium Cohn p.p. (1875: 58). 



The members of this genus are all entomogenous, and were long 

 thought to be obligate in their parasitism. In recent years 

 several species have been induced to grow saprophytically on 

 artificial culture media (Sheldon, 1903; Speare, 1912; Sawyer, 

 1929) and it is probable that others will be obtained in culture 

 when the proper conditions are provided. 



In nature, infection of the host results when a germ tube 

 from the conidium penetrates the outer covering of the insect 

 and enters the body cavity. In the host the infection thread 

 usually does not develop a profusely branching mycehum. 

 Instead it forms short thick segments which break apart from 

 one another, and undergo a process of division and budding. 

 These segments are termed hyphal bodies. The process is con- 

 tinued until the body cavity is almost wholly filled with them. 

 Meanwhile, powerful enzymes are excreted which quickly dissolve 

 the various internal structures of the host until practically 

 nothing remains but the chitinous outer coat. Under unfavor- 

 able environmental conditions the hyphal bodies may assume 

 heavier walls, and enter a period of rest as chlamydospores. On 

 the return of favorable conditions they germinate quickly and 

 proceed at once to the formation of conidiophores. In the more 

 normal development chlamydospores are lacking and the conidio- 

 phores arise from the thin-walled hyphal bodies. They penetrate 

 the outer covering of the host and form conidia in the air. In 

 some species the primary hypha, without branching, abjoints 

 terminally a single conidium. In others considerable branching 

 may occur, each ultimate branch becoming a conidiophore. In 

 either case the conidium is formed as a bud at the apex of 

 the clavate termination of the conidiophore. It enlarges as the 

 protoplasm of the conidiophore passes into it, and when the 

 mature shape and size have been attained it is cut off from the 



