430 RESEARCHES ON FUNGI 



a pair of basidia as 3 and 5 is decided by stimuli which affect the 

 nuclei. Exactly how these stimuli operate is at present a matter 

 for speculation. It may be that mutual stimuli are conducted 

 from one basidium to the other by means of protoplasmic con- 

 nections passing through one or more cells of the subhymenium ; 

 or, possibly, stimuli are provided by the mutual pressure of the 

 basidia, by a gaseous emanation, or by transpiration. Possibly 

 some day the matter may be decided by performing minute 

 operations on the hymenium with the aid of instruments for micro- 

 dissection such as have been used by Kyte. The mutual adjust- 

 ment of the positions of the spores on neighbouring basidia only 

 takes place when the basidia producing the spores simultaneously 

 are in contact or nearly in contact ; but basidia which are relatively 

 distant from one another, e.g. nos. 11 and 16, do not seem to in- 

 fluence one another in any way, and a prediction of the probable 

 relative positions of their spores is impossible. The corners- 

 of-a-square arrangement of the spores of two adjoining bisporous 

 basidia of a Cultivated Mushroom exactly resembles the corners- 

 of -a -square arrangement of the four spores of a quadrisporous 

 basidium of the Wild Mushroom. Two adjoining bisporous basidia, 

 therefore, appear to respond to the stimulus which decides the posi- 

 tions of the spores like the two halves of a quadrisporous basidium. 



The coming -generation basidia (nos. 8, 18, 28, 36, 42, 46, 55, 

 and 60) are destined to produce the next crop of spores after the 

 spores on the sterigmata of the present -generation basidia have 

 been discharged. Like the present -generation basidia they are 

 distinctly protuberant, but they differ from these in that they do 

 not bear spores. They develop sterigmata in the later stages of 

 their growth. Nos. 42, 46, and 55 are not yet fully protuberant, 

 as they are relatively young : they are associated with present- 

 generation basidia which bear very rudimentary spores. On the 

 other hand, nos. 60, 8, 18, 28, and 36 are fully protuberant, for 

 their bodies have attained maximum length : they are associated 

 with present-generation basidia which bear relatively mature 

 spores. The cell-contents are not shown but, if they were, we 

 should see that the body of each coming-generation basidium was 

 filled, or almost completely filled, with fine protoplasm. 



