Ill 



Take some fresh spores from an ascidium, and place 

 them in a drop of water on the surface of a fresh leaf 

 of some Gramineous plant : after keeping it in moist air 

 for about 4860 hours, strip off a part of the epidermis, 

 or better, cut tangential sections 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 aecidium 

 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 aecidium 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 endo- 

 spore, with four germinal pores, arranged equatorially ; 

 here the inner wall is wanting: note the protoplasmic 

 contents with reddish granules. 



Attempts should be made, as above directed for the aecidium 

 spores, to infect leaves of the Barberry and of the Grass with these 

 uredo-spores, when the infection will be found to succeed on the 

 Grass, but not on the Barberry. 



The infected Grass plants which have produced 



