LEPIOTA CEPAESTIPES 



II 



of each sporabola has been supposed to be about 0-1 mm., as in 

 the Mushroom. From the fact that the spores measure 7-8 by 

 5 /i and from the observations of the rates of fall of spores of 

 various sizes given in Volume I.,^ it may be inferred that, in still 

 air, the rate of fall of the spores of Lepiota cepaestipes in a vertical 

 direction between the gills is about 1 mm. per second. At this rate 

 of fall, a spore would take 4 seconds 

 to fall from the top to the bottom 

 of one of the interlamellar spaces 

 shown in Fig. 5. 



The pileus-flesh is composed of 

 large, loosely-compacted hyphae 

 between which are well-developed 

 interhypal air-spaces (Fig. 5). 

 Similar hyphae are to be found in 

 the trama of the gills, but here 

 they are placed in more or less 

 transverse positions, so that they 

 cross the mid-plane of each gill from 

 one subhymenium to the other. In 

 Lepiota procera the tramal elements 

 have an approximately similar 

 disposition (Fig. 17, B, p. 27). By 

 reference to Fig. 9 (p. 16), it will 

 be seen that the trama has the 

 lightest possible construction : its 

 organisation reminds one of the trellis-work or web in the girders 

 of iron bridges ; although, of course, it is not in the least mathe- 

 matically regular. Each gill can be divided into hymenium, sub- 

 hymenium, and trama. 



Very thin transverse sections through parts of the gills, made 

 when the pileus is beginning to expand, take on shapes like those 

 shown in Fig. 6. A study of such sections teaches us that, in the 

 uninjured gills, there are certain strains and stresses normally set 

 up, which make for gill-rigidity and which are of importance in the 

 expansion of the pileus. Strips of the hymenium and subhymenium, 



1 These Researches, vol. i, 1909, p. 175. 



Fig. 4. — Lepiota cepaestipes. Part 

 of a transverse section through 

 an unexpanded pileus {cf. Fig. 

 2, left), showing: packing and 

 shape of the gills, and the 

 nature of the trama and pileus- 

 flesh. The sterigmata were 

 just beginning to develop on 

 the most protuberant basidia. 

 Magnification, 15. 



