192 
18. The sporophores each bearing a single uredospore. How 
many nuclei in each spore? 
Make a prawinc of the uredinium in section as seen under the micro- 
scope. 
The first production of uredospores furnishes inoculum for the secondary 
cycles, which are repeated often during the summer on currants and goose- 
berries. 
In some cases the telial stage is produced from the same mycelium 
which produced the first crop of uredospores, and thus the primary cycle 
may be carried forward to the production of sporidia from the germinating 
teliospores. 
In the prepared slides showing uredinia in section, NOTE:— 
19. The stroma developed just beneath the uredinium and the 
radiating mycelium extending into the host-tissue. Find a haustorium. 
DRAW. 
In prepared slides showing the telial stage, OBSERVE :— 
20. That the telial horns arise directly from the same stroma 
that bore the uredospores. DRAW. 
21. The telial horn, composed entirely of teliospores cemented 
together into a compact mass. DRAW. 
22. The germination of the teliospores, forming a short germtube 
which is septate,—the promycelium. DRAW.” 
23. The sporidia produced on sterigmata from each cell of the 
promycelium. 
The sporidia, produced as the last step in the primary cycle, initiate 
secondary cycles on the five-needled pines. The sporidia are formed during 
periods of wet weather. The teliospores germinate as soon as formed, 
there being no rest-period required. There is no saprogenesis in the life- 
history of this pathogene. 
Secondary Cycles. There are two sorts of secondary cycles in the 
case of this pathogene; those initiated by sporidia on pine, and those 
initiated by uredospores in currant and gooseberry leaves. The repeated 
succession of secondary cycles, initiated by uredospores, causes the rapid 
spread of the fungus from the currants and gooseberries harboring the 
primary cycles, until by the end of summer the fungus may be disseminated 
over several square miles. 
These secondary cycles on gooseberry and currant leaves duplicate 
the primary cycle, in that after the uredospores are dispersed, telial horns 
are produced from the same stromata and upon germination of the telio- 
spores, promycelia bearing sporidia are formed.’ The sporidia of the 
primary and secondary cycles are the inoculum which initiate the secondary 
cycles on the five-needled pines. 
Very probably the sporidia are forcibly discharged from the sterigmata 
and they are blown to the pine. They are short-lived and must find 
suitable conditions for germination soon or they will not function. The 
sporidia germinate by a germtube and this penetrates uninjured pine 
bark initiating a new mycelium. The steps in the development of the 
symptoms on pine have already been observed. Spermagonia may be 
formed in the autumn of the next year following infection. Aecia may 
be formed the second spring after infection or the production of the first 
crop of aecia may be delayed for several years. 
