RIDDLE. — ON THE CYTOLOGY OF THE ENTOMOPIITHORACEAE. 193 



bodies may not take place, in which case the hyphae often become 

 septate. These septa cut off cells containing relatively few, regularly 

 spaced nuclei which from their larger size have evidently an increase 

 of elliciency. The tendency toward nuclear reduction has extended to 

 the conidium resulting in a uni-nucleate condition. The resting- 

 spores are formed by the fusion of coenogametes, with relatively few 

 nuclei, — these coenogametes being of a simple type, where all of the 

 nuclear material enters the zygote. In Basidiobolus the hyphae are 

 regularly septate and do not normally form hyphal bodies. It has been 

 shown, however, by Raciborski (96*) that under certain culture condi- 

 tions such a formation of h}T^)hal bodies may be induced. The tendency 

 to nuclear reduction has here reached its highest expression, resulting 

 in uni-nucleate cells. Accordingly the zygote is formed by the fusion 

 of two uni-nucleate cells, which must, however, from a phylogenetic 

 view-point, be considered coenogametes. The production of the peculiar 

 beak-cells is clearly a late specialization and makes these coenogametes 

 of the second of Davis's types, namely, where only a portion of the 

 nuclear material is functional. 



If the evolutionary line thus indicated be the true one, it is reason- 

 able to expect that Empusa, as the primitive form, will show a possible 

 derivation from other Phycomycetes. The close agreement of the 

 methods of zygospore-formation, both as to general morphology and as 

 to cytological conditions, between Entomophthora and the Mucorales, 

 which has been pointed out above, indicates relationship in that 

 direction. If we consider such a form as Sporodinia, we find h}^hae 

 with very numerous small nuclei ; a sporangium forming a number of 

 uni-nucleate spores ; and zygospores formed by the fusion of primitive 

 coenogametes. Apogamy in this species is of frequent occurrence ; 

 and it is reasonable to assume that the azygospores thus formed are 

 multi-nucleate. Comparing with this the conditions in Empusa, we see 

 at once a possible line of derivation. The hyphal bodies, into which, 

 on account of the peculiar endophytic habit, the hyphae break, contain 

 many small nuclei, which are, however, less numerous and larger than 

 those of Sporodinia. Thaxter ('88) has already shown that the "co- 

 nidium " of Empusa might be regarded as a sporangium. It is clear 

 therefore that, just as the coenogamete is a gametangium into which 

 has been extended the coenocytic habit and which accordingly functions 

 as a unit, so the " conidium " of Empusa is a sporangium into which 

 has been extended the coenocytic habit and which likewise functions 

 as a unit. Apogamy has become constant in Empusa, resulting in the 

 formation of multi-nucleate azygospores. The close relationship of 

 Empusa and Sporodinia seems undeniable. 



AOL. xr.ii. — 13 



