17 



of the centrifuge tube was then carefully drawn off with a 

 pipette,: thus concentrating the entire sediment in 1 cc. or less 

 of water. This sediment was given a thorough microscopic 

 examination, primaril}^ to determine whether the spores of the 

 blight fungus present were pycnospores or ascospores, but also 

 to get an idea of the other kinds of spores which the insects 

 were carrying. 



RESULTS OBTAINED FROM THE CULTURES. 



As has already been stated, insects Nos. 1-18 and 23-25 were 

 taken from certain experiments carried on in the laboratory 

 and insectary at Philadelphia. All of these were red ants 

 belonging to tlie same species (Table I). Before being tested 

 Nos. 1-3 and 10-18 were permitted to run over pieces of moist- 

 ened chestnut bark bearing active peri thecia, while Nos. 4:-Q 

 had run over bark bearing spore horns. ;! f\ 



Of these 21 ants, 5 yielded positive results, two of them 

 carrying 2,733 and 4,000 spores of Endothia parasitica respect- 

 ively (Table I). Only One of these five had had access to 

 pycnidial material, while the other four had been on and ab6ut 

 bark bearing active perithecia. 



