110 PRACTICAL BOTANY. 



though not so regular : note the thickened and striated 

 outer wall. 



Prepare similar sections from a young blotch, in which all 

 the aecidia have not yet ruptured the epidermis of the host : and 

 note 



1. The origin of the secidia in the mesophyll of the host. 



2. That the secidia are relatively narrow when young, the 

 hymenium growing hroader as it grows older, by intercalation of 

 new basidia. 



3. The traces of displacement, and ultimately of rupture of the 

 superficial tissues of the host. 



4. The outgrowth of the peridium as a tube open at the 

 apex, and extending beyond the general surface of the Berberis 

 leaf. 



Returning to the spermogonia, observe 



1. The closely packed, parallel, rod-like hyphae 

 converging to the centre (sterigmata). 



2. The minute oval bodies (spermatia) abstricted 

 from them, and escaping through the narrow pore on 

 to the outer surface of the leaf. 



3. The brush of hyphaB which protrude through the 

 narrow pore. 



A careful teasing out of the spermogonia with needles, and 

 examination under a high power will be a profitable exercise. 

 Attempts may also be made, with suitable precautions, to cultivate 

 the spermatia in various nutritive solutions. 



VI. It is known that the aacidium-spores of this 

 fungus will not infect the Barberry plant afresh, but 

 will only germinate so as to infect a Grass plant ; thus 

 the fungus is an example of " Hetercecism." The spores 

 retain their germinating power only for a short period. 



