INTRODUCTION 



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Fig. 119. Class Basidiomyceteae. Diagrammatic sketches comparing the nuclear 

 behavior in the formation of the ascus and the basidium and the further steps leading 

 to the production of the ascospores and basidiospores, respectively. (A) Development 

 of the ascus and ascospores. (B) Development of the basidium and basidiospores. (a) 

 Dicaryon terminal cell of a hypha. (b) union of the two nuclei to form a diploid nucleus; 

 (c, d) as the cell enlarges the first and second meiotic divisions occur, the daughter 

 nuclei in each division being indicated by a connecting line; (e) ascospores are formed 

 around each nucleus in the ascus; (f) external pockets are formed near the apex of the 

 basidium; (g) a wall is formed surrounding the cytoplasm and nucleus and separating 

 them from the sterigma. Spores are now mature. 



according to the observations of Buller (1909). The distance to which the 

 spores are discharged may be ten to twenty times the length of the spore. 

 By affixing a clean glass coverslip a short distance above the surface of the 

 mature hymenium, e.g., a gill of a mushroom, the basidiospores will 

 sometimes be found sticking to the glass in groups of four. In this manner 

 it is possible to obtain and make cultures from the four spores arising 

 from a single basidium. Buller has made very extensive studies of this 



