PLUTEUS CERVINUS 



107 



in which case the two minor hooks thus produced may be equal in 

 size or one may be larger than the other, the inequality exhibiting 

 all gradations. The wall of a cystidium is thin below but thickens 

 where the shaft protrudes into an interlamellar space, and it is 

 thickest at the hooks (Fig. 51, a and 6). Treated with chlor-zinc 

 iodine, the thicker parts of the wall swell up and become violet-red. 

 At the same time strings or discs, which cross the free end of the 



Fig. 50. — Pluteus cervinus. A, surface view of a gill during the spore-discharge 

 period, showing the distribution of the spore-bearing basidia, as indicated 

 by their spores, and of the cystidia, as indicated by their branched apices : 

 a a, basidia from which a spore has just been discharged ; b b, basidia about 

 to discharge their spores ; c c, basidia with spores that have just attained 

 full size ; d d, basidia with spores about two-thirds the full size : e, basidia 

 with very rudimentary spores ; //, basidia with spores just coming into 

 existence on the ends of the sterigmata ; g, h, and i, cystidia with .3, 4, and 5 

 prongs respectively. B, another similar drawing but with the cystidia, j, 

 represented by median sections instead of by their apices ; letters b-f, as in A. 

 Drawn with the camera lucida. Magnification, 293. 



cystidium and at first resemble cell-walls, stain yellow and thus 

 indicate that they contain proteins and are merely layers of cyto- 

 plasm separating vacuoles from one another (Fig. 51, v). 



The basidia taper slightly at both ends and become protuberant. 

 At first it seemed that the basidia were dimorphic, i.e. that some 

 were longer and more protuberant and others shorter and less 

 protuberant ; but this supposition turned out to be an error. 

 Basidia which have spores about to be discharged are all equally 

 protuberant ; but young basidia begin to develop sterigmata and 

 spores before their bodies have attained full length (Fig. 51). This 

 I have not 3'et noticed in any other species. The result is that 



