COPRINUS STERQUILINUS 211 



given in detail in Volume 11/ it seems clear that we can regard 

 the two successive generations of basidia which arise in the 

 former species as comparable with the first two of the numerous 

 successive generations which arise in the latter species. Since the 

 structure and development of the hymenium of most species of 

 Coprinus are similar to those of Coprinus sterquilmus, we may say, 

 speaking generally, that in the Coprini the number of generations 

 of basidia has become reduced to tivo and that the development of 

 the second generation takes place earlier th^n it does in such a 

 non-Coprinus fungus as Panaeolus campanulatus. In the Panaeolus 

 Sub-type, spores do not begin- to devjelop on the sterigmata of a 

 succeeding basidial generation until those on the sterigmata of 

 the preceding basidial generation in the immediate neighbourhood 

 have been discharged. In the Coprini, however, this is not the 

 case, for in them the development of the spores of the second- 

 generation basidia is hastened, so that, shortly after the basidia 

 of the first generation have begun to develop spores, the basidia 

 of the second generation begin to develop spores also ; and this 

 overlap in the development of the two basidial generations is of 

 such a nature that the second-generation basidia develop some- 

 what faster than the first-generation basidia, with the result that, 

 in the end, just before spore-discharge takes place, on any small 

 hymenial area (0-1 mm. square, cf. Fig. 90, D), not merely all the 

 basidia of the first generation, but also all those of the second, 

 bear spores which are full-grown, perfectly ripe, and ready for pro- 

 jection from the sterigmata. The comparison of hymenia which 

 has just been made and which has an important bearing upon the 

 question of the evolution of the Coprinus Type maj^ perhaps be 

 still more fully realised by comparing Fig. 90, D (p. 210) in this 

 volume with Fig. 98, A (p. 292) in Volume II. 



A few more facts still remain to be recorded concerning the 

 behaviour of the nuclei. The spores, whilst growing from tiny 

 rudiments to full size, are unprovided with nuclei ; but, soon after 

 they have attained full size, a nucleus appears in each, as is 

 shown in Fig. 89 at h (p. 208), which represents a living basidium 

 seen in water. By using appropriate staining reagents applied to 



1 Vol. ii, 1922, pp. 264-297. 



