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but, being the product of a reduction-process, they might properly be 

 called carpo-spores (Fig. 381, 5-, s). Their peculiarity is that they do 

 not cause infection on the Wheat, but can penetrate the epidermis 

 of the Barberry. Acting on the suspicions already aroused, the 



FIG. 382. 



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

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

 magnified. (After Marshall Ward.) 



infection was first made by De Bary in 1864. He found that the 

 carpospores easily shed from the sterigmata germinate to form a 

 germ-tube, which can directly penetrate the epidermal wall of the 

 Barberry (Fig. 382). This initiates the second phase, and as the 



FIG. 383. 



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

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

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



carpospore itself was haploid, so is the stage produced from it on 

 the Barberry. Each cell has only a single nucleus. 



A section through an infected spot on the Barberry leaf shows the 

 effect of the attack in the greatly increased thickness as compared 

 with the normal leaf (Fig. 383). The enlarged cells of the mesophyll 



