CHAPTER V. — COMPARATIVE REVIEW. — ENTOMOPHTHOREAE. 1 59 



a shrivelled drying mummy, surrounded by a circle of spores or gonidia which have 

 been thrown off. The latter are capable of immediate germination, and do germinate 

 if duly supplied with moisture, either emitting a germ-tube which penetrates at once 

 into the body of a suitable insect and goes through the process of development above 

 described, or only producing short tubes from the extremity of each of which a new 

 secondary gonidium with the same qualities as the primary is abjointed. The 

 gonidia soon lose the power of germination ; in Empusa Muscae, for example, it does 

 not continue beyond about fourteen days. 



The Fungi are limited to the above course of development in most of the insects 

 which they attack. In some cases, however, few or no gonidia are formed and 

 zygospores or azygospores are ultimately developed, and in most species inside the 

 body of the insect. Nowakowski gives the following description of the formation 

 of zygospores in Entomophthora ovispora and E. curvispora. The cells of adjacent 

 hyphae develope an H-shaped union by means of the necessary processes, and 

 establish an open communication at the point where the processes are in contact with 

 one another. Then a spherical protuberance makes its appearance near the 

 point of union, either on the cross-bar of the H or close to it, and receiving 

 as it grows the entire protoplasm of the conjugated pair of cells is finally delimited 

 by a membrane, and becomes a zygospore in the sense in which the word is used in 

 the case of Piptocephalis. 



No azygospores have been observed in these species. But Entomophthora 

 radicans and the species of Empusa examined by Nowakowski have only azygospores 

 which are produced without conjugation as lateral outgrowths on the mycelial tubes 

 or acrogenously like the gonidia, as in the species named by Nowakowski Lamia 

 culicis. It would appear therefore that there is a difference in the matter of con- 

 jugation in the different species similar to that which is found in the Saprolegnieae 

 as regards the presence or absence of the antheridial branches. Both zygospores 

 and azygospores become resting spores in the same way. The membrane 

 becomes much thickened and is differentiated into a thick usually bright yellow 

 episporium with a smooth surface in most species, and a thinner endosporium, while 

 a large, globular, nearly central drop of oil separates in the protoplasm from 

 the general finely granular turbid mass. The mycelium is dissolved and disappears 

 after the formation of the resting-spores, which are therefore the only remains of the 

 plant in the mummified body of the insect. Their germination was observed 

 by Nowakowski in Empusa Grylli, and consists in the emission of a short tube, the 

 promycelium, which forms a gonidium at its apex ; the gonidium is abjected, in the 

 same way as gonidia from the gonidiophores described above. 



The above account is a summary of Brefeld's and Nowakowski's observations. The 

 differences in the statements of the two writers with regard to conjugation are to be 

 explained by the different behaviour of different species. The genetic connection once 

 frequently assumed between the Entomophthoreae and other Fungi, especially Saccharo- 

 mycetes and Saprolegnieae, is a subject for the history of botanical errors. Information 

 on the point will be found in the works cited below. 



Cohn has described as Tarichium a species which preys on ground-caterpillars ; it 

 has only resting-spores with thick walls roughened on the outside with warts, and may 

 perhaps belong to this section. In Nowakowski's opinion both the development and 

 affinity require to be more closely examined. 



