1914] THAXTER—NEW ZYGOMYCETES 357 



Choanephora, the peculiar characteristics of its sporangiospores 

 being in themselves sufficient evidence of this relationship. But 

 the chief interest which attaches to it rests upon the fact that the 

 conidia so characteristic of Choanephorae are here replaced by 

 sporangiola similarly related to large spherical heads; and further 

 that these sporangiola, in the life history of one and the same 

 species, pass by almost insensible gradations to large typical soli- 

 tary sporangia such as are produced normally by a species of 

 Choanephora. If, however, one compares the conidial fructification 

 of C cucurbitarum , for example, with the sporangiolate fructifica- 

 tion of the present type, one is unavoidably impressed by the close 

 correspondence between them, both in the form, peculiar color, 

 and ornamentation of the spores, and in the similar origin of conidia 

 and sporangiola from large spherical heads. The conclusion seems 

 almost inevitable that in the conidia of Choanephora we are 

 dealing with a condition in which the sporangiola of the present 

 type are replaced by single spores which have been called conidia, 

 but which should in all probability be regarded as monosporous 

 sporangiola. On this supposition it might even be questioned 

 whether the two types should be separated generically. 



The writer has been unsuccessful in attempting to separate 

 mechanically an outer thin wall from the colored and ornamented 

 wall of the conidia in C. cucurbitarum; but that such a thin wall, 

 corresponding to the sporangiolum wall, may actually be present 

 is suggested by the fact that sometimes in normal heads, but more 

 often in those in which the spore formation has been arrested or is 

 m some way abnormal, one finds a condition like that represented 

 in fig. iSA. In such instances the contents of the "conidium" has 

 contracted away from the base of the thin colorless mother cell 

 wall, and has surrounded itself with the characteristic purple 

 'conidial" wall, which is clearly distinguished from the empty space 

 below it, as is indicated in the figure cited. No indication has been 

 seen, however, of the formation of more than one spore in this 

 supposed sporangiolum. In all the species of Choanephora, more- 

 over, the conidial heads when not primary arise from a primary 

 head, not from a subdichotomously branched hypha- termination as 

 in the present instance, and the distinction between sporangia and 



