148 ROLAND THAXTER ON THE 



midway between the two conjugating cells in a fashion analogous to the similar process 

 in Spirogyra. The intervening walls between these two gametes, or conjugating out- 

 growths, are then absorbed and a mingling of their contents ensues. A bud then appears 

 (fig. 322) on one or both the gametes, which increases rapidly, as a rule appropriating 

 the entire contents of each conjugating cell to form the zygospore. A septation of the 

 hyphae above and below the point of conjugation is often seen, but is not invariable, 

 resembling in this respect the similar process in Conidiobolus previously described. It 

 may be mentioned, in passing, that the chief distinction between the two rests on the 

 fact that here we have a zygospore formed by budding, while in Conidiobolus the spore 

 is produced directly within one of the conjugating cells. In this, as in other cases, the 

 empty hyphae disappear rapidly after the zygospores have been formed; a circumstance 

 which, together with the rapidity of the process as a whole, accounts for the infrequency 

 with which conjugation in Empusae can be observed. In one case, however (^JE. rJiizo- 

 spora) , the hyphae after conjugation become brown and horny, holding the spores firmly 

 in a spongy mass (fig. 374) ; but even here the process of conjugation can only be seen 

 during a short period, while the spore is developing, owing to the subsequent contraction 

 and distortion of the hyphae. 



In JE. ecJiinospora, in which the zygospores are often external, a modification of this 

 Spirogyra-like process is found, which deserves to be mentioned. Here (figs. 298-802), 

 we have a conjugation taking place between two filaments in a manner similar to that 

 described above ; but, instead of arising by budding from one of the gametes or in their 

 immediate vicinity, the spore commonly develops as a terminal swelling from the end of 

 one of the conjugating hyphae. 



In addition to these types of conjugation, a singular form, not, I believe, noticed hith- 

 erto in Bntomophthoreae, occurs in E. Fresenii. It is, as far as I have observed, invari- 

 able in this species and is never associated, as is usually the case, with the production of 

 azygospores. The hyphal bodies, as they occur in the host just prior to the production 

 of conidia or zygospores, are almost perfectly spherical and very uniform ; and are de- 

 rived from large, shapeless bodies which have the appearance of naked protoplasm. The 

 spherical hyphal bodies lying side by side within the host proceed to conjugate in a man- 

 ner indicated in the succession of figures 127 to 135. A slight projection first appears 

 from the upper inner end of either hyphal body (fig. 128) . These projections soon 

 meet midway between the hyphal bodies (fig. 129), after which a bud begins to rise di- 

 rectly above their point of union (fig. 130) . The contents of both bodies pass into this 

 bud, forming the mother cell of an elliptical zygospore which, I believe, afford^ the only 

 known exception to the usual spherical shape. After the spore is mature, the two hyphal 

 bodies usually persist for some time as bladder-like appendages (figs. 135-136), which 

 slowly disappear (figs. 137-140). 



This is certainly a very simple process, yet it demonstrates I think, more clearly than 

 has yet been possible among Entomophthoreae the existence of an undoubtedly sexual 

 process of a distinctly zygosporic type. In Conidioiolus, Basidioholus, and even in the 

 examples from Empusa previously given, there is usually a more or less marked differ- 

 ence in the size of the gametes, which, in the first-named genus, led Brefeld to consider 

 the family as belonging to the Oosporeae; but, in the present instance, we have the ga- 



