324 RESEARCHES ON FUNGI 



end the spores will be placed in as favourable positions as 

 possible. Evidently, adjacent basidia exercise a mutual influence 

 of a complex kind upon one another during development : the two 

 nearest sterigmata of two basidia which develop at the same time 

 in close proximity tend to bend away from one another : when 

 one sterigma of a basidium bends inwards toward the basidium- 

 axis, the opposite sterigma bends inwards also, and at the same 

 time the other pair of sterigmata become divergent as if repelled 

 from the first pair. This results in the rhomboidal arrangement 

 which can so readily be observed. 



The Cheilocystidia. In addition to the basidia and the 

 paraphyses, the hymenium of many of the Agaricineae contains 

 elements of a third kind which are known as cystidia. The 

 cystidia are usually very protuberant, and are often considerably 

 larger than either the paraphyses or basidia. They were originally 

 called cystidia because they are often swollen and appear as cysts. 

 Cystidia occur in the genera Coprinus, Pluteus, Inocybe, Russula, 

 etc. Now the cystidia on the gills of many Agaricineae can be 

 divided into two groups according to their location. Those which 

 occur on the sides of the gills we may call pleurocystidia on account 

 of their lateral position, whilst those which are present on the free 

 lower edges of the gills we may call cheilocystidia. Some lamellate 

 fungi possess both these kinds of cystidia, others one kind only, 

 and yet others are lacking in both. Panaeolus campanulatus 

 is unprovided with pleurocystidia, but possesses a considerable 

 number of cheilocystidia. The free gill-margin of this species is 

 devoid of basidia and therefore of spores, and the cheilocystidia 

 are present in such large numbers that the gill-margin appears to 

 the naked eye as a white line. 



My investigations upon the cheilocystidia of Panaeolus cam- 

 panulatus were made upon freshly-gathered fruit-bodies obtained 

 from a grassy field in England close by a house which I was using 

 as a laboratory. The fringe of cheilocystidia extends upwards 

 above the extreme edge of the gills in some fruit-bodies to a 

 maximum distance of 0-1 mm., but in others not so high. Each 

 cheilocystidium has a somewhat swollen base embedded in the 

 hymenium and is prolonged outwards beyond the general level of 



