262 PROCEEDINGS OF THE AMERICAN ACADEMY 



observed feeding on the secretions of the spermogonia ; yet as these 

 are usually confined to the upper surface of the leaves, it is difficult to 

 understand the agency of such insects iu fertilizing a female organ 

 borne supposedly on the under side. 



Turning now to the individual cultures my results with the different 

 species were as follows. 



G. MACROPUS. 



April 30. Sporidia sown on 



3 Pyrus Americana. 



4 Pyrus malus. 



3 Cratceyus coccinea. 

 May 11. No result. All the plants reinfected, and in addition 



2 Amelanchier Canadensis. 

 1 Pyrus arhutifolia. 



May 13. Spots with spermogonia appeared on single leaves of two 

 apples ; but being questionable, the leaves were cut off. 



May 22. Spermogonia appeared abundantly on two apples. 



May 28. Two additional plants of Pyrus malus infected, on which 

 spermogonia appeared. 



June 5. Sjioridia sown on immature fruit of Amelanchier, which was 

 kept under a bell glass. 



June 12. Signs of secidia forming on the under side of the apple 

 leaves first infected, while the leaves of those infected May 28 

 withered and ultimately fell off from no apparent cause. The 

 remaining plants yielded no result whatever. 



July 10. Peridia began to show on the two apples first mentioned 

 as affected. These developed slowly, and towards the end of July 

 were recognizable as belonging to the ^cidiuvi pyratum of Schwei- 

 nitz. It did not however assume the penicillate form peculiar to 

 this Ronstelia until exposed to the weather; when the peridia, 

 formerly long and barely lacerate, were turned back in the char- 

 acteristic fashion. 



G. CLAVARI^FORME. 



April 30. Sporidia sown on 



3 Pyrus Americana. 

 3 Pyrus malus. 



May 11. No result, and the same plants reinfected with the addi- 

 tion of 



3 Cratcegus tomentosa. 



