338 



DISEASES OF FIELD & GARDEN" CROPS. [CH. 



but so small and gauzy that they may be readily over- 

 looked. One of these small and inconceivably thin 

 wings is shown enlarged to 20 diameters at Fig. 143, 



20 



FIG. 143. 



Green fly, from potato plant, natural size, and wing with spores or conidia 



of the potato fungus, Peronospora infestans, Mont., at A. 



Enlarged 20 diameters. 



and on the wing at A, engraved to the same scale, are a 

 number of conidia or spores of the potato fungus. Small 

 as these germs are as seen on the greatly enlarged wing, 



