68 MANUAL OF FRUIT DISEASES 
disease was then held. Several years elapsed before it was 
recognized that another stage of G. Juniperi-virginiane oc- 
curred on the apple. Prior to this discovery the stage on the 
apple was referred to as Restelia Pyrata. After the hetercecious 
habit of the fungus was established, the last name was dis- 
carded and the former name was, and is now, used to designate 
it in all of its stages on the cedar and the apple. 
In the spring basidiospores, or sporidia, are blown from the 
gelatinous horns of the cedar-apple to the young leaves and 
fruits of the apple. In some cases they may be carried several 
miles, but most of them do damage only at a mile or less. 
Under favorable conditions the sporidia germinate. Low 
temperatures, such as prevail in April and May, are most 
favorable to the germination of the sporidia. The germtubes 
penetrate the apple-leaf through the cuticle on the upper sur- 
face. The mycelium develops locally within the leaf, occupying 
the spaces between the cells and sending haustoria into the 
cells. As a result of the stimulative action of the mycelium, 
the leaf is hypertrophied, due to an excessive enlargement and 
multiplication of the cells in the lower part of the leaf (spongy 
parenchyma). These cells become elongated and the inter- 
cellular spaces of the spongy parenchyma are obliterated. 
The apple-fruit tissues are at first enlarged, but finally growth 
of the fruit at the point of attack is stopped, which fact explains 
the marked dwarfing and reduction in size. -About one month 
after infection, the mycelium forms the first fruiting bodies of 
the season. These are on the upper surface of the leaf or on 
the fruit and are called pycnia (spermagonia). Spores are 
developed within the pycnia and are called pycnospores (sper- 
matia); their function is unknown. They do not reproduce 
the fungus. Within a short time after the spermagonia appear, 
the cup-shaped bodies develop on the lower surface of the leaf 
opposite the spermagonia; these are known as cia. About 
the middle of July these open and their spores, called ecio- 
