46 RESEARCHES ON FUNGI 



doubtless function as guards and prevent adjacent gills from coming 

 into contact during the development of the spores. Each cystidium 

 (Fig. 31, d) has a thin cylindrical stalk about 20 [j. long and a body 

 which is ventricose below, becoming narrower and obtusely rounded 

 above. The length of each isolated cystidium is 80-100 [o, varying 

 in very large fruit-bodies up to 150 y., while the breadth of the 

 ventricose part of the body is 25-28 [i.. The pleurocystidia of 

 C. plicatilis, relatively to those of C. micaceus, C. lagopus, and 

 C. niveus, are but slender structures. 



The ends of the short gills are free from basidia but bear cheilo- 

 cystidia (Fig. 24, p. 41). These more or less resemble the pleuro- 



A B C D E 



•!• ••. 1* • ::. t • 



Fig. .30. — Coprinus plicatilis. Variations in number of spores on a basidiiun 

 viewed from above. A, a normal basidium bearing four spores. B-D, 

 abnormal basidia : B, with three spores ; C and D, each with five spores. 

 E, three isolated normal spores lying on one side in water. Fruit-body 

 obtained at King's Heath, England. Magnification, 587. 



cystidia in form but are smaller. The ends of the long gills bear 

 swollen cells (Fig. 24, p. 41). 



As the pileus expands, adjacent gills come to be moved widely 

 apart ; and, when expansion is just complete, the cystidia can be 

 seen with the microscope projecting from the gill-sides as free pegs. 



The Spores. — The spores are deep black, both en masse in a 

 spore-deposit on white paper and when seen individually under 

 the microscope. Their dimensions, relatively to the basidial axis, 

 are three : length, breadth, and thickness. The average dimensions 

 for fifty spores obtained from a single fruit-body which grew on 

 a lawn at Birmingham, England, measured with the Poynting plate- 

 micrometer, were 12-9 X 10-7 X 7-9 [x.i When seen from in front 

 or behind {i.e. when one looks from or toward the axis of the 

 basidium), a spore appears heart-shaped or, in some fruit-bodies, 

 spindle-shaped ; and, when seen from above {i.e. when one looks 



^ These Researches, vol. i, 1909, p. 162. 



