304 RESEARCHES ON FUNGI 



We are now acquainted with the fact that the production and 

 liberation of spores is the outcome of a number of complicated 

 developmental changes. Let us recapitulate the more obvious of 

 these changes in so far as they concern the basidium. A basidium, 

 on beginning to mature, grows in length and volume, and at the 

 same time gradually fills with protoplasm. On attaining full size, 

 its two nuclei unite. The fusion-nucleus then forms four daughter 

 nuclei by two successive karyokinetic divisions. Then the four 

 sterigmata are brought into existence, and afterwards the spores. 

 The four nuclei then creep up, or are drawn through, the sterigmata 

 into the spores, so that each spore comes to have one nucleus 

 only. For some hours the basidium pours cytoplasm and food 

 materials into the spores, so that in the end the spore-contents 

 become very dense indeed. The metabolism taking place in a 

 maturing spore involves, among other processes : the temporary 

 production of glycogen, the thickening of the cell-wall, and the 

 manufacture of a brown pigment ; and a mature spore excretes 

 a tiny drop of water from its hilum just prior to its being forcibly 

 shot away from its sterigma. Each spore, immediately after being 

 discharged, provided that no hindrance arises from misplaced 

 gills, creeping insects, violent winds, etc., escapes dow r n an inter- 

 lamellar space into the free air beneath the pileus and is then 

 carried off by the wind. It would be astonishing, if, in view of 

 all the complex changes which take place during the production 

 and liberation of spores, every spore out of all the millions pro- 

 duced were to succeed in escaping from a fruit-body. As a matter 

 of fact, a considerable number of spores is always wasted. These 

 victims of some accident, which has occurred either during develop- 

 ment or discharge, adhere most tenaciously to the gills and only reach 

 the earth when the fruit-body which has produced them collapses and 

 undergoes putrefaction at the end of the spore-fall period. 



While the absolute number of spores which are wasted is 

 frequently large, often amounting to several millions, the ratio of 

 the wasted spores to the whole number produced may be small. 

 It is well to bear this in mind : otherwise it may be thought that 

 the wonderful arrangements for securing the successive production 

 of mature basidia are to a large extent rendered nugatory by an 



