58 MELAMPSORA PINITORQUA 
point, combined with this lateral curvature, causes S-shaped 
distortions which have given rise to the name “ Pine Branch 
Twist” for the disease (Fig. 35). 
It is suggested by Massee that the zecidiospores can repro- 
duce the excidia and thus propagate the parasite on the Pine 
without reference to the alternate host, but no proof is given of 
this statement. The mycelium is almost certainly perennial 
in the affected branch, and thus fresh outbreaks arise year by 
year more or less, according to the weather in the spring. 
If the ecidiospores are blown on to a leaf of Aspen, they 
germinate there and the mycelium produces uredospores during 
Fig. 35. Melampsora pinitorqua (from a German specimen, ex herb. 
Sydow). «, a young shoot of Pine, in June, with newly-formed 
leaves, showing three ceomata (@), shaded; the leaves have been 
removed from the affected portion, which is beginning to be curved; 
b, w ceoma, x10; cv, ecidiospores; d, old leaf of Aspen, showing 
numerous teleuto-sori on the lower surface ; e, teleutospores. 
the summer: these are usually so abundant as to cover the 
underside of the leaves, and the parts on which they occur show 
plainly as yellow spots on the upper side. For a time, the 
uredospores spread the disease rapidly during the growing 
season, until sometimes all the leaves of a tree are more or less 
attacked and are covered with a bright orange powder. As 
the leaves begin to die, teleuto-sori are formed; at first these 
are brown, and show as little angular crusts on the under side. 
Afterwards, when the leaves are fallen off, the crusts begin to 
turn almost black as the teleutospores mature. These spores 
are produced beneath the epidermis, standing erect and side by 
