REPORT OF THE STATE BOTANIST, I919 47 



The question of whether these cystidia on the edge differ from the 

 sterile cells in origin has not been settled, and depends somewhat on 

 how much of the surface of the edge is meant when referring to 

 " edge "of the gills. Massee shows no figure demonstrating that the 

 larger " marginal cells " are different in origin from the cystidia on 

 the sides of the gills. 



The cystidia may, like the spores, be classed under two main 

 types : the thick-walled cystidia, and the thin-walled cystidia. (a) The 

 former are the " true cystidia " of Massee. Their walls are quiie 

 diick and highly refractive, frequently thickened only along the 

 upper two-thirds of the cystidia, so that the wall of the pedicels 

 remains unthickened. At the apex they exude crystalloid masses at 

 maturity by the deliquescence of a small area or pore at the apex. 

 1 agree with Massee that the presence or absence of these caps at the 

 apex of the cystidia is of no morphological value in classifying the 

 species. The different age of the gills or influence of external con- 

 ditions during development would modify the observation on dif- 

 ferent specimens of the same species. The thick-walled cystidia 

 are generally, although not in all cases, quite ventricose above the 

 pedicel, while above this enlargement they taper more or less tov.-ard 

 the subacute or subrounded apex. This type is usually numerous, 

 especially toward the edge of the gills, {b) The thin-walled type of 

 cystidia has either thin walls corresponding in thickness to that of 

 the pedicel, or when somewhat thickened as is frequently the case 

 in older plants, the thickening tends to run around the apex and is 

 uniform, whereas in the thick-walled type the wall varies markedly 

 in thickness, usually thickest a short distance from the apex. Fur- 

 thermore, the majority of the thin-walled type are entirely subcylin- 

 drical above the pedicel or if ventricose at all, the portion above is 

 not abruptly narrowed to a lance-like neck as in many thick-walled 

 cystidia, but remains broadly cylindrical to the broadly rounded or 

 subtruncate apex. However, this type may show considerable varia- 

 tion from the commoner shape just described, and this is not unusual 

 in the same plant. The commonest variation is that where there is a 

 gradual tapering from the broadest part of the cystidium to its. 

 apex, which may even be acute ; there is also a tendency in this type 

 of cystidia to taper gradually, instead of abruptly, to the slender 

 pedicel. The thin-walled cystidia also tend to be less numerous; 

 in most species of this group they are scattered or scanty and may 

 be almost lacking- In L s u b f u 1 v a Pk. they are reduced to the 

 condition of " sterile cells" and are often found with difficulty. 



