420 RESEARCHES ON FUNGI 



Levine. 1 The first of these observers showed that, when traversing 

 a sterigmatic neck, a nucleus undergoes a great alteration in shape : 

 it becomes drawn out into a filament. The other workers have 

 observed fibrillar strands leading upwards from the nuclei into 

 the sterigmata and sometimes into the spores. According to 

 Levine, at the end of the second nuclear division in the basidium- 

 body, the four centrosomes become attached to the free end of 

 the wall of the basidium and the four daughter nuclei become 

 reconstructed in close connection with them. The four nuclei 

 then move downwards somewhat in the basidium but maintain 

 their connections with the centrosomes by means of fibrillar strands. 

 The positions which the centrosomes take up at the free end of the 

 basidium-wall mark the points of origin of the sterigmata ; and, 

 as these structures develop, the centrosomes are carried up in their 

 tops. The fibrillar strand connecting each nucleus with its centro- 

 some becomes elongated during this process. When the spores 

 begin to be formed on the ends of the sterigmata, the centrosomes 

 still remain attached to the cell-wall and come to occupy positions 

 destined to be the spore-apices. Each fibrillar strand again elon- 

 gates during the growth of the corresponding spore to full size, 

 so that eventually the four nuclei which may be situated some 

 distance down the basidium-body, are attached by relatively 

 very long and thin fibrillar strands with the centrosomes at the 

 apices of the spores. 2 Maire, Fries, and Levine all agree that the 

 fibrillar strands are associated in some way with the passage of 

 the nuclei into the spores. The strands occupy the paths of the 

 nuclei and possibly direct the nuclear migrations. Levine says 

 that, since the strands pass not merely through the sterigmata 

 but also into the spores, they may be of significance in the 

 apparently difficult process of passing the nuclei through the 

 extremely narrow sterigmatic necks. I am inclined to agree with 

 this view. It remains, however, to be discovered whether the 

 strands are kinoplasmic and contract, so that they drag the 

 nuclei into the spores, or whether they merely represent lines of 



1 M. Levine, " Studies in the Cytology of the Hymenomycetes, especially the 

 Boleti," Bull. Torrey Botanical Club, vol. xl, 1913, p. 173. 



2 M. Levine, loc. cit., pp. 172-173. 



