20 The Ohio Journal of Science [Vol. XVI, No. 1, 



fruited only asexually, producing aplanospores and akinetes. 

 But several of the collections show all the forms of reproduction 

 in different cells of the same filament. 



The characteristics of this species suggest that the peculiar 

 Zygnema reticulatum, which was described by Hallas in 1895*, 

 is in reality a Debarya. The fact that the reproductive cells 

 become filled with cellulose, that the aplanospores are very 

 irregular in form and that the vegetative cells contain as high 

 as seven chromatophores, are all in harmony with this idea. 

 On this basis it is also easy to understand the most notable 

 peculiarity of the species — that spores derived from cells with 

 several chromatophores produce two or three sporelings. 



With the addition of the two new American species and this 

 Danish species Debarya reticulata (Hallas) nov. comb, the 

 description of the genus needs to be modified as follows: 



Vegetative cells cylindrical or constricted at the ends, 

 varying from 1-16 diameters in length; chromatophore varying 

 from an axile plate with two or more pyrenoids to stellate 

 chromatophores, each with a central pyrenoid. Reproduction 

 by zygospores formed of the complete contents of the game- 

 tangia; not cut off from the gametangia by partition walls; 

 but in the process of conjugation, as the gametes pass into the 

 conjugating tube, their place is taken by a secretion of cellulose. 

 Aplanospores occupying only part of the sporogenous cell, the 

 remainder being filled with cellulose. All spores variable in 

 form. Parthenospores and akinetes occur not infrequontly in 

 some of the species. The walls of the aplanospores and par- 

 thenospores resemble the zygospores of the same species in 

 their markings. 



There are now eleven described species belonging to this 

 genus. D. immersa W. West and D. africana G. S. West 

 bear a close resemblance to Mongeotia sphaerocarpa Wolle. 

 D. Ilardyi G. S. West has much the same appearance as 

 Mongeotia viridis (Kutz) Wittrock. D. desmidiodes W. & G. S. 

 West, D. calospora (Palla) W. & G. S. West, D. reticulata, 

 D. americana, and D. decussata have characters in common 

 with the Zygnemas. D. glyptosperma has the vegetative 

 characters common to several of the species, but its spores are 

 quite unique among the Zygnemales. 



*Hallas, E., Om en ny Zygnema-Art med Azygosporer. Bot. Tidsskrift 20:1-16. 

 1895. 



