56 CRONARTIUM RIBICOLA 
of Ribes (Fig. 34); they have been recorded on 26 out of about 
50 known species. The spermogones and ecidia are formed on 
stems and branches of the five-leaved species of Pinus: they 
have been found on five out of the eighteen Pines of that group, 
but do not attack species having 2 or 3 leaves in a fascicle. 
The following account is founded on that of Spaulding (1911). 
The basidiospores are formed about the beginning of August, 
and if they are blown by the wind, and adhere to moist young 
branches of the Pine, the germ-tube enters and produces a 
mycelium which. lives in the branch for several years, ultimately 
causing it to become considerably swollen in a fusiform or 
irregular manner. In about half the cases it is the main trunk 
Fig, 34. Cronartium ribicola. a, a spore of Peridermium Strobi, x 600; 
6, the teleutospore-columns on leaf of Red Currant (reduced); c, a uredo- 
spore; d, top of a column of teleutospores, x 600. 
that is infested. On this swollen portion spermogones appear 
at almost any period of the year, followed in spring by the 
ecidia, which break through fissures in the bark; these may 
be even as much as 1 cm. high, yellowish-white in colour, with 
orange spores. When the peridium bursts open, in an irregular 
manner, the spores may be carried by the wind to any plants 
of Rabes that may be near and can at once infect them. The 
distance to which the zcidiospores can be effectively carried is 
estimated to be less than 500 ft. These spores cannot infect 
the Pine; but if they fall upon a moist leaf of Ribes, the uredo- 
pustules usually appear, on the underside, in from 10 to 20 days. 
These uredospores can, as usual, reproduce themselves on 
