PANAEOLUS CAMPANULATUS 



325 



the hymenium into a fine cylindrical hair, so that the whole cell 

 is often 0-05-0-06 mm. long (Fig. 113, A). The tip of the cell 

 usually excretes a drop of mucilage (B), and often the drops of 

 neighbouring hairs become confluent, as is shown in Fig. 113 

 at C. Some of the largest drops, formed by the confluence of 

 drops from about twelve cystidia, may be as much as 1 mm. 

 wide and can just be distinguished by the naked eye. It was 



FIG. 113. Panaeolus campanulatus. The cheilocystidia and their excretions. 

 A, two young isolated cystidia. B, two cystidia projecting from a gill-edge, 

 one of which has excreted a drop of mucilaginous fluid. C, part of the free 

 lower margin of a gill, turned upwards and seen from the side, showing the 

 hymenium on the side of the gill and the cheilocystidia projecting outwards 

 from the gill-edge ; a, a ball of mucilaginous fluid formed by the confluence 

 of two drops excreted at the tips of two cystidia ; b, a hemispherical mass of 

 mucilaginous fluid formed by the confluence of about ten drops excreted at 

 the tips of as many cystidia. Magnification, 293. 



found that such drops tend to be plano-convex, apparently owing 

 to the fact that the drops are unable to pass from the tips down 

 the shafts of the cystidia (Fig. 113, C, &). When such a gill-edge 

 as is shown in Fig.' 113 is placed in water, the mucilaginous drops 

 can still be seen for some time. They are not therefore imme- 

 diately soluble in water. When exposed to air, the drops do not 

 dry up anything like so quickly as would equally large drops of 

 pure water. Knoll investigated similar hairs to these for several 

 species of Agaricineae and came to the conclusion that they are 

 hydathodes. He therefore called them trichome-hydathodes. 1 The 



1 F. Knoll, " Untersuchungen iiber den Bau und die Function der Cystiden 

 und verwandter Organe," Jahrb. f. wiss. Bot., Bd. 50, 1912, pp. 453-501. 



