KNT0M01MITII0RKAK OF THE UNITED STATES. 



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metes exactly alike, and in addition to this a process of development in the zygospore 

 similar to that occurring among the Mucorini in Piptocephalis. The regularity of this 

 process, and of the resulting zygospores, is worthy of mention ; and although the hyphal 

 bodies are collected in an indiscriminate mass, the details of the process never show the 

 slightest variation from that described above. 



Before leaving the subject of conjugation in Empusae, a singular method, by which 

 the resting spores of E. Q-rylli are often formed, must be described. This species is re- 

 markable for the great variety it exhibits in the details of the formation of its azygo- 

 spores; but in certain cases it seems not impossible that even in this species we may have 

 true conjugation of a type quite different from those previously described. The suc- 

 cessive figures, 31 to 35, indicate the nature of this process. In the first place we have, 

 before reproduction of either type, a condition characterized by the presence of irregu- 

 lar, rounded hyphal bodies of various size and shape (fig. 31). Instead of producing an 

 azygospore by any of the methods above described, one of these bodies may become 

 septate by the formation of a median cross partition (fig. 32). An elevation of the cell 

 wall presently appears around the hyphal body, between the cells thus formed, which 

 develops into a two-lipped fold (figs. 33 and 34). The partition between these two cells 

 is then apparently absorbed, for the contents of one gradually pass into the other to form 

 a "zygospore" (fig. 35). A variation of this process is found in the similar division of 

 the swollen extremity of a hypha (figs. 38-39) the lip-like folds in each being quite 

 peculiar. In many cases the formation of a resting spore is not accomplished by a sin- 

 gle division and subsequent union; but only results after a succession of oblique divis- 

 ions always accompanied by the lip-like folds, as in figs. 36 and 37. Spores of this kind 

 are usually characterized by their flattened bases, and in some instances two such spores 

 may be formed, one in either cell of the divided hyphal body, as often occurs in other 

 conjugating cells. "Whether this is in reality a form of conjugation, I do not feel pre- 

 pared to say; and careful observations, by means of cultivations of the hyphal bodies, 

 are much to be desired. This process may in a measure explain the appearance previ- 

 ously alluded to (p. 147) and represented in figs. 214-21G. Here there is no production 

 of a lip-like fold, yet it seems not impossible that in such cases a short hypha may have 

 divided and conjugated with itself, so to speak; the zygospore arising as a lateral bud 

 instead of developing directly within one of the divisions. Such an explanation may 

 seem somewhat far-fetched, yet the division of a hypha and subsequent conjugation with 

 itself are practically what occurs even in Basidiobolus. 



The mature azygospores as well as the zygospores in all known species are, with the 

 exception of E. Eresenii, spherical in shape; and in the majority of cases are indistin- 

 guishable in the different species, except by slight variations of size. There are, how- 

 ever, three notable exceptions to this rule. The spores of Tarichium megaspermum 

 Cohn 1 are characterized by a deep brown outer wall, or epispore, which is marked by 

 sinuous reticulations. In E. echinospora (figs. 303-305), the epispore develops numerous 

 sharp spines which separate it from all other known species; while in E. rhizospora the 

 brownish spore is held by numerous rhizoid-like outgrowths from its base (figs. 374- 

 375). A dark brown epispore seems also characteristic of E. callipliorae Giard (E. 

 muscivora Sehroeter) . 



1 l*. c. B. 



MEMOIRS BOSTON SOC. NAT. HIST., VOL. IV. 22 



