418 RESEARCHES ON FUNGI 



filled with dense protoplasmic contents. The development, ripen- 

 ing, and discharge of the spores of the present-generation basidia, 

 as we have seen, take about eight hours to accomplish. During 

 this time, the coming-generation basidia interspersed between them 

 are by no means quiescent. They first complete the growth in 

 length and diameter of their basidium-bodies, so that these become 

 equal to those of the present-generation basidia (cf. b and c, on 

 the right-hand side of Fig. 146). Then the fusion-nucleus in each 

 basidium divides and so produces nuclei which are subsequently 

 to be translated to the spores. I have not attempted to study 

 the nuclear divisions in the basidium, and therefore am unable 

 to state from my own observations whether the fusion-nucleus 

 divides into two or four nuclei. However, Rene Maire, who made 

 a cytological investigation upon the bisporous basidia of a Cultivated 

 Mushroom, states : that there are two nuclei in the young basidium 

 which unite to form a fusion-nucleus (secondary nucleus) ; that 

 this nucleus then behaves in the usual manner, i.e. it produces 

 four nuclei by two successive divisions a process probably accom- 

 panied by the reduction of the chromosomes to one-half x ; and 

 that, after the first of these nuclear divisions has taken place, the 

 basidium begins to produce its two sterigmata. 2 The development 

 of the sterigmata is a slow process which requires at least thirty 

 minutes. Usually a coming-generation basidium begins to develop 

 its sterigmata about half an hour or so before the moment when the 

 nearest present-generation basidium will discharge its last spore. 

 Thus the sterigmata of the coming-generation basidia are almost 

 ready (within 15 minutes or so of being ready) to develop spores at 

 the moment when the hymenium in their immediate neighbourhood 

 has become cleared of the spores of the previous generation of 

 basidia. Thus one crop of spores is quickly followed by another. 

 It is in consequence of this very orderly mode of development 

 of one generation of basidia after another that by far the greater 

 part of the hymenium at any moment is found to contain spore- 

 bearing basidia. As soon as a basidium begins to develop the 



1 Rene Maire, " Recherches cytologiques et taxonomiques sur les Basidio- 

 mycetes," Bull Soc. Myc. France, T. 18, 1902, p. 151. 



2 Ibid., p. 152. 



