ANTHRACNOSE OF CUCURBITS. 25 
As a result of the examination of a considerable number of these 
preparations, it was found that within 24 hours after inoculation 
appressoria had been formed in abundance, usually one to each spore, 
sessile, or on short germ tubes. These were particularly numerous 
Fia. 1.—Surface view of a portion of a cucumber-leaf epidermal cell, showing appressoria and penetration 
tubes, six days after inoculation. In five instances the empty spore case is shown lying near the 
appressorium. The circular germ pores can be seen in the appressoria. ‘Two appressoria (upper right) 
have formed short penetration tubes. Another has produced considerable mycelial growth within the 
host cell. (Camera-lucida drawing; magnified about 395 times.) 
in the vein depressions and in the depressions bounding the epidermal 
cells. No signs of host penetration were found in this material or in 
material fixed 44 hours after moculation. 
In leaf areas fixed 65 hours after inoculation, penetration tubes 
were commonly visible within the epidermal cells underneath the 
appressoria and a 
small round pore 
was visible in the 
wall of the appres- 
sorium next to the 
host cuticle (fig. 1). 
Hasselbring noted 
similar pores in the 
appressoria of the 
apple bitter-rot 
fungus. In mate- 
rial fixed 121 hours 
Fic. 2.—Surface view of epidermal cells of a cucumber leaf, showing intra- after inoculation, 
cellular mycelium from three appressoria, six days after inoculation. when Macroscopic 
(Camera-lucida drawing.) symp toms were 
already apparent, the penetration tubes were found under a large 
percentage of the appressoria, and in many cases considerable 
mycelium was found in the epidermal cells underneath (fig. 2). 
69806°—18—Bull. 7274 
