PANAEOLUS CAMPANULATUS 269 



this area retain its individuality from first to last throughout its 

 development ? One cannot answer with an unqualified yes. The 

 fact is that, whilst the earlier generations of basidia were being 

 produced, the contour of the area remained practically unchanged ; 

 but, whilst the later generations were being produced, some parts 

 of the area lagged considerably behind others in development. 

 Into the details of the alteration of the individuality of the original 

 area it is unnecessary to go. It will be sufficient to say that, in 

 arriving at the estimate of the amount of time which was required 

 for the maturation of each successive generation, my attention was 

 fixed on one and the same small part of the area. 



Another question arises in connection with the density of 

 distribution of the spore-bearing basidia : was this density the 

 same for all the generations ? The spaces separating the basidia 

 of the first generation observed were equal to those shown in the 

 central black area of Fig. 89 (p. 257). The number of basidia 

 per square 0-1 mm. in the second, third, and fourth generations 

 observed, was about the same as in the first generation. Then a 

 diminution took place. The basidia of the fifth generation were, 

 on the average, farther apart than those of the first, second, third, 

 and fourth ; and those of the sixth and seventh farther apart than 

 those of the fifth. 



The significance of gill-mottling and the economy involved in 

 the production of successive series of generations of basidia have 

 yet to be discussed ; but it will be of advantage to postpone this 

 discussion until the reader has first been made acquainted with 

 the structure of the hymenium in detail. As we shall see, the task 

 of interpreting the nature of the hymenial elements will be con- 

 siderably facilitated by the knowledge, based on direct observation, 

 that, on any small hymenial area, the basidia come to maturity 

 in a series of successive generations. 



Description of the Hymenium of Panaeolus campanulatus in 

 Detail. Previous descriptions of the hymenium of the Non-Coprinus 

 Agaricineae have all been incomplete. Where mottling of the 

 gills occurs, as in the Panaeoli and Psalliota campestris, the pro- 

 duction of successive generations of basidia has been overlooked. 

 There has usually been some doubt whether paraphyses, i.e. elements 



