COPRINUS STERQUILINUS 255 



If one places a living gill flat on a glass slide under a cover- 

 glass without any mounting fluid , and if one then watches the spore- 

 free zone with the high power of the microscope, one can observe 

 the autodigestion of the.hymenial elements (Fig. 104, zone d, p. 242). 

 A cell undergoing autodigestion first loses its turgidity, and then 

 its walls become granular. Soon, the cell-contours become indis- 

 tinct ; and eventually they disappear. The granular particles 

 derived from the cell-walls persist for a time ; but they gradually 

 become more and more difficult to trace and, in the end, most of 

 them seem to disappear altogether. It is not improbable that the 

 walls become resolved into a thin mucilage. The basidia are more 

 persistent than the paraphyses, and the projecting long basidia 

 than the non-protuberant short basidia. The part of each basidium 

 to disappear last . is the free end crowned with the remains of the 

 sterigmata. This is probably due to the fact that the free end 

 of each basidium does not sink down in the hymenium and become 

 involved in the general autodigestive fluid until some minutes after 

 its last spore has been discharged (c/. Fig. 105, I and s in zone d, 

 p. 249). Traces of the basidia, which appear flattened from above 

 downwards, can still be seen at the top of the zone of the products 

 of autodigestion (Fig. 104, zone e, p. 242). The zone of auto- 

 digestion in Fig. 105 has been drawn to correspond with that in 

 Fig. 104. There is no doubt that the process of autodigestion 

 involves not only the hymenium but also the subhymenium and 

 trama, and the destruction of these inner parts of a gill has there- 

 fore been represented in the zone d of Fig. 105 (p. 249). The only 

 cells of a gill which escape autodigestion are the waste spores. The 

 zone of autodigestion, whilst moving upwards on a gill, gradually 

 comes to involve every spore which was not successfully discharged 

 when it was in the zone of spore-discharge. One such spore is shown 

 on the left-hand side of Fig. 104 at m and another at n (p. 242). 



When giving an account of the autodigestion of the gills of 

 Coprinus comatus in the first volume of this work published in 1909, 

 I expressed the opinion that the phenomenon is brought about by 

 appropriate enzymes liberated from the cell-sap of the dying cells ; ^ 

 but, at that time, there was not any experimental proof that such 

 ^ Researches on Fungi, vol. i, 1909, p. 200. 



