212 RESEARCHES ON FUNGI 



microtome sections, the four nuclei of certain basidia were observed, 

 as it were, in the act of entering the bases of the sterigmata ; and 

 there can be no doubt that, as in other Hymenomycetes, the four 

 nuclei of each basidium-body make their way through the extremely 

 narrow sterigmatic passages into the spores. A nucleus, after 

 creeping into a spore, rounds itself oflp (Fig. 89, h) and soon divides 

 into two (j and k). Two nuclei were observed several times in 

 living spores immersed in water and also in dead spores which had 

 been stained. Sometimes, in a living spore, four rounded bodies 

 could be made out (1), but I was unable to decide whether they 

 were nuclei or merely vacuoles. 



An important phase of the development of the four spores of 

 a basidium is the passage into them of the contents of the basidium- 

 body. Before a basidium develops its spores it is usually loaded 

 with protoplasm, and no prominent vacuole is to be seen within 

 it. With the development of the spores and their growth to full 

 size, a vacuole makes its appearance toward the base of the basidium- 

 body and gradually extends its boundary in the direction of the 

 spores until, eventually, it comes to occupy the whole of the in- 

 terior of the basidium-body with the exception of the tip of each 

 sterigma. Its wall is a very thin layer of cytoplasm which is closely 

 appressed to the cell-wall. The existence of this layer of cyto- 

 plasm must be assumed, for only by its presence could the osmotic 

 pressure of the cell-sap, upon which the turgidity of the basidium- 

 body depends, be maintained during the ripening and discharge of 

 the spores. An advanced stage in the development of the vacuole 

 is shown at h in Fig. 89 (p. 208). The growth of the vacuole is an 

 indication that the contents of the basidium-body are passing 

 upwards into the spores. The emptying of the basidium-body 

 and the corresponding filling of the four spores takes several hours 

 for its completion. The basidium is evidently a spore-mother-cell 

 in that its dominating function is to produce and discharge spores. 

 It yields practically all its contents to its four spores, thus providing 

 them with protoplasm which is rich in food materials and suited 

 to the production of germ-tubes and rudimentary mycelia. There 

 is evidently a direct relation between the capacity of a basidium- 

 body and the collective capacity of the four spores which it produces. 



