MELAMPSORA PINITORQUA 57 
any leaves of Ribes to which they may be carried, thereby 
forming a means of rapidly spreading an infection which is 
once started. After a few weeks, brownish thread-like growths 
appear in the uredo-sori: these are the filaments on which the 
teleutospores are borne, and the latter may be found from July 
until the fall of the leaf, and even upon the fallen leaves. The 
teleutospores may germinate at once, perhaps also after a con- 
siderable time, but the basidiospores which they produce can 
only infect young branches of Pine as described above. They 
are distributed by the wind, but probably cannot be carried to 
any great distance. Owing to the long incubation period of 
the mycelium which will produce the ecidiospores, the fungus 
cannot be seen on the Pine until it is at least three years old, 
although infection may have taken place in the seedling: by 
that time the leaves have naturally fallen off the part which 
received the infection. 
Though this disease does little harm to the currant, it is 
necessary to destroy the infested bushes, since they form a focus 
of infection for the Pines. Weymouth Pines that are more 
than 20—25 years old are rarely liable to attack. 
Melampsora pinitorqua. 
THE PINE AND AspEN Rust. 
The ecidial stage of this Melampsora lives on young shoots 
of Scots Pine (Pinus silvestris) and its uredo- and teleuto-stages 
on leaves of Aspen (Populus tremula). 
The teleutospores germinate after a winter's rest, and the 
basidiospores infect the young pine-buds, just beginning to 
elongate in May and June. The mycelium produced penetrates 
the cortex, and reaches also the bast and medullary rays. On 
these shoots the spermogones appear about the end of May, 
and are followed by the ecidia. The cortex of the affected part 
becomes orange and dead, while the unaffected part still con- 
tinues to grow. Thus thin shoots may be killed altogether, 
but in the thicker ones curvature takes place owing to the 
one-sided growth: the negative geotropism of the growing 
