BLAKESLEE. — SEXUAL REPRODUCTION IN THE MUCORINEAE. 237 



Dicranophora fulva Schroter. 



Schrbter ('86^ ) is the only one wlio lias found or described this species 

 which is reported growing on Paxillus involutus. The zygospores are 

 formed on the mycelium, which develops abundantly between the lamel- 

 lae of the host and arise from the copulation of two erect unlike branches. 

 One of them is very thick and sack-like, arising from a mycelial hypha by 

 a narrow stalk, and its upper third is distinguished by a cross wall for the 

 formation of the zygospore. The second branch is hardly thicker tlian 

 the hypha from which it originates, and from it a short cylindrical piece 

 is cut off. *' The unlike character of the copulating branches, especially 

 in size and thickness, points distinctly to a sexual difference in the 

 branches and suggests an antheridium and an oogonium." Figure 113 

 of Schrbter ('97), in Engler and Prantl, leaves no doubt as to the hetero- 

 gamic character of this species, but the figure is not sufficient to show the 

 connections of the suspensors. The closely related American form 

 subsequently referred to, however, is homothallic. 



Choanephora Cunninghamiana Currey. 



The species was found by Cunninghum ('80) on the flowers of Hibiscus 

 in India. The following statements occur in connection with the descrip- 

 tion of the formation of zygospores. " This happens comparatively rarely, 

 and I have as yet been unable to determine what the precise conditions 

 are under which it occurs. ... In all cases in which I have been able to 

 determine the point accurately, the opposed organs have been derived 

 from two distinct mycelial filaments. In many cases, however, the rela- 

 tions of the processes and filaments are very much obscured . . . and 

 in some the appearances seem to indicate that contact occasionally oc- 

 curred between processes arising from the same filament." 



The evidence thus indicates a heterothallic condition. 



Choanephora Simsoni Cunningham. 



The species was found by Cunningham ('95) on Ipomoea rubro-caerulea. 

 In both this and C. Cunninghamiana the nutrition was found to regulate 

 the fructification, zygospores being obtained when the nutriment was 

 below the normal. " There is nothing to indicate what is the essential 

 determinant of the appearance of zygospore fructification, for in two cul- 

 tures side by side from the same specimen of nutrient material zygospores 

 are absent in the one and almost entirely replace the sporangia in the 

 other. ... In some instances the conjugating processes take origin from 



