6 BOTANICAL GAZETTE [july 



The secondary gills originate at varying distances from the 

 stem in the same manner as the primary gills, and their develop- 

 ment progresses outward. Young secondary gills are shown in 

 figs. 20, 22, 37, and 38. They are also well shown in a transection 

 of the fruit body (figs. 24, 39). The primary gills during their 

 origin and development are attached to the stem (figs. 9, 15, 30, 32), 

 and in a transverse section of a fruit body (fig. 24), but they become 

 free during the general expansion of the fruit body (fig. 23). In 

 Agaricus rodmani Atkinson (7) found that the gills were often 

 attached to the stem in the early stages of development. 



ORIGIN OF CYSTIDIA 



During the -origin of the gill saHents the cystidia begin to appear 

 (figs. 34-36). Text fig. 3 shows in outline the position of cystidia 

 and basidia in the basidiocarp shown in fig. 36 as accurately 

 as could be determined. As shown here, the filaments bearing 



both cystidia and young basidia 

 pass out from the trama in a 

 usually unbranched condition, the 

 cystidia being only distinguishable 

 from the basidia by their more 

 scanty protoplasmic content and 

 larger size. As the gills develop, 



however, the filaments leading out 



Fig. ^. ^Course of filaments form- , ,1 ,•■,■ ■, 1 1 



, J , J- . . to the cystidia become enlarged 



ing trama and leadmg out to young -' " 



basidia and cystidia. and for some time remain little, 



if at all, branched, while those bear- 

 ing basidia and paraphyses are smaller and much branched (figs. 

 38, 47, 47a, text fig. 4). A and B of text fig. 4 show the details of 

 the gills at this stage as definitely as could be determined, A being 

 a reconstruction of the portion shown in fig. 47a. A slightly older 

 gill is shown in fig. 48 and text fig. 5, A showing the detail of the 

 cystidium shown in fig. 48, and 5, C, D, E, and F showing parts of 

 other gills in the same series. The filaments bearing the cystidia 

 seemingly branch somewhat during the later development and give 

 rise to basidia and paraphyses, but even with the highest powers of 

 the microscope it was difficult to determine positively. Cystidia 



