396 



BOTANICAL GAZETTE 



[NOVEMBER 



drawn from a specimen with sporangia like those in tig. 9, B and C, 

 and in this respect is characteristic. 



Sections of sporangia, like those shown in fig. 9, B and C, 

 show that the smaller sporangia contain no spores at all (fig. 10). 

 In most of these cases the sporangium wall is from 4 to 6 cells 

 thick, with the inner layer not differentiated into a definite tape turn, 

 and the outer lacking the anticlinal thickenings so characteristic 

 of sporangia which produce even imperfect spores (fig. 11). In 

 extreme cases the sporangium is a mere mass of parenchyma cells ; 

 in others, a narrow streak of mucilage indicates that sporogenous 

 tissue had begun to form; in still others, like the one shown in 



& ■„ 



1 



I 





1 



fa 



--■■ 



.V 





k ** 









A 



B 



C 



D 



Fig. 9. — A,B, C,B,dissectutn; Z>, B. obliquiim; X2 



mass 



muci 



many 



consisted partly of imperfect, disorganizing spores. 



In the apparently perfect sporangia of B. dissectum 

 of the spores are somewhat smaller than the average size for 

 B. obliquum, and there are many spores which look as if they might 

 be abortive. Fig. 11 shows six spores still floating in the tapetal 

 Plasmodium. The two spores at the upper left, one of them 



are doubtless abortive; of the other four, 



outline 



only the one at the 

 spore of B. obliquum. 



diameter 



pidermal 



sporangia 



