234 PRACTICAL BOTANY 



cells resemble that of the spores themselves though not so 

 regular : note the thickened and striated outer wall. 

 Returning to the spermogonia, observe 



1. The closely packed, parallel, rod-like hyphas 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 hyphae which protrude through the narrow 

 pore. 



VI. It is known that the secidium-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 

 " Heteroecism." The spores retain their germinating power 

 only for a short period. 



Take some fresh spores from an aecidium, and place them in 

 a drop of water on the surface of a fresh leaf of some Gramin- 

 eous plant : after keeping it in moist air for about 48 60 hours, 

 strip off a part of the epidermis, or better, cut tangential sec- 

 tions of that part on which the spores have been placed : mount 

 in water with the outer surface of the epidermis uppermost, 

 and examine under a medium power : observe that the secidium 

 spores have produced tubular hyphae, which make their way, 

 through the pores of the stomata, into the tissues of the Grass 

 plant. 



VII. Infect a Grass plant with secidium spores and keep it 

 in a moist atmosphere : .in about a week reddish swellings will 

 appear about the points infected, and the epidermis will be 

 ruptured. 



Cut transverse sections so as to traverse one of these ruptured 

 spots : mount in water, and observe under a medium power : 

 note 



1. The branched mycelium ramifying in the tissue of the 

 Grass. 



2. The ruptured epidermis. 



3. The closely packed uredo-spores of simple oval form, 

 borne on thin pedicels (basidia). Observe further the exospore, 

 rough with small outgrowths : the endospore, with four 



