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very close together in the hymenium, as shown in fig. 42. At this 

 stage of development the approximate hymenia of two adjacent 

 lamellae are still more or less separated, showing distinct gill 

 chambers, but the numerous cystidia already project above the level 

 of the young basidial hymenium. At certain places two cystidia 

 from opposite hymenia meet head on and the pressure sometimes 

 results in a deformity of one or both. Even at this stage of develop- 

 ment it can be seen that many of the cystidia originate below 

 the subhymenium. In this respect my observations do not agree 

 with those of Buller (12a), who describes and figures the cystidia 

 of C. atramentarius as arising from the small subhymenial cells at 

 the same level as the origin of the basidia. 



In older stages of the lamellae (figs. 44 and 45) the approxi- 

 mate hymenia of adjacent lamellae become very closely crowded 

 together, so that the gill chambers are entirely obliterated. The 

 hymenia are very compact and deeply stained, while the trama 

 presents a loose open mesh and is lightly stained. One of the 

 striking features at this stage is the appearance of the cystidia in 

 cross-sections of the gills. With low magnification they appear 

 as quite regularly spaced clear areas, oblong or elliptical in outline, 

 lying directly across the two approximate hymenia. With low 

 magnification it is often difficult or impossible to determine from 

 which lamellae a given cystidium originates. With higher magni- 

 fication one can readily determine the lamella from which they 

 arise. Now it is very clear that many of them, at least, originate 

 from hyphae of the trama below the subhymenium. I have not 

 examined the situation thoroughly enough to make any general 

 statement. It is possible that some of them may arise from sub- 

 hymenial cells on a level with the origin of the basidia, as Buller 

 states, but it is very certain that many of them originate in the 

 trama. In fig. 45 a cystidium is shown which originates from the 

 middle of the trama. 



During the growth of the cystidia they push their way into the 

 hymenium of the adjacent lamella, according to my observations, 

 much farther than illustrated by Buller. The one shown in fig. 45 

 has pushed through the hymenium of the adjacent gill. Many 

 of them reach this distance and some even extend into the 



