BASIDIOMYCETES 



437 



swelling appears, and into it the protoplasm and nucleus pass. These 

 are sometimes called sporidia : each is the product of a reduction- 

 process and is recognised as a basidiospore (Fig. 335, s, s). Their 



Fig. 336. 



Sporidia, or basidiospores, of Puccinia, germinating on the epidermis of a Barberry 

 leaf, and putting out germ-tubes, which penetrate the cell-walls. Very highly 

 magnified. (After Marshall Ward.) 



peculiarity is that they do not cause infection of the Wheat, but can 

 penetrate the epidermis of the Barberry. Acting on suspicions 

 already aroused, De Bary succeeded in carrying out an experimental 

 infection in 1864. He found that the basidiospores, easily shed from 



Fig. 337. 

 Vertical section through a patch of aecidia (<?) and spermogonia (s) on the 

 Barberry leaf, showing the swelling of the diseased part. The small aecidium 

 to the right has not yet burst. Highly magnified. (After Marshall Ward.) 



the sterigmata, germinate to form a germ-tube, which can directly 

 penetrate the epidermal wall of the Barberry (Fig. 336). This initiates 

 the second phase : and as the basidiospore itself is haploid, so is the 

 stage produced from it on the Barberry. Each cell has only a single 

 nucleus, which may be held to indicate a haploid condition, as in the 

 gametophyte. 



