INJURIES INDUCED BY PLANTS 159 



yellow, roundish or irregular, cushion-like swollen blotches. 

 Pseudo-peridium yellowish white, closed at the shoulder, 

 ruptured on the side by numerous longitudinal fissures, which 

 extend to the surface of the leaf. These longitudinal fissures 

 are bridged over by short transverse rodlets, whence the whole 

 peridium appears grated. In this connection I may remark that 

 I have repeatedly observed the pear-rust in great abundance 

 in places where no examples of the above-mentioned host- 

 plants of the teleuto form were to be found within a wide 

 radius. 



GYMNOSPORANGIUM TREMELLOIDES 



To the three above-mentioned species a fourth falls to be 

 added, whose aecidium form is very abundantly met with in 

 the Bavarian Alps on Sorbus Aria and .S. Chamcemespilus, and 

 which as sEcidium pencillatum has already been described as an 

 independent form (Fig. 88). 



In equal abundance one meets in the same region with a 

 teleuto form on Juniperus communis which does not agree with 

 any of the above-named species, but whose connection with the 

 aecidium form on Sorbus Aria has been proved by infection- 

 experiments in the garden of the Munich institute of forest 

 botany. 



The teleutospore-layers appear in May on Juniperus com- 

 munis, as hemispherical orange yellow to yellowish brown masses, 

 which, as in the case of Nostoc communis, are mucilage- like 

 in texture and capable of swelling (Fig. 89, a a}. They 

 easily drop off when the branches are shaken, and then pale 

 yellow smooth scars remain, which are often I cm. in diameter 

 (Fig. 89, b b}. The spores are all about the same size, being 

 approximately 4045 microm. long and 2025 microm. broad. 

 The two short abruptly conical cells, whose height is about 

 equal to their greatest diameter, are provided with smoky- 

 grey walls. Some of them coalesce all along their base, others 

 are to a certain extent separated owing to contraction in fact, 

 it not unfrequently happens that the two parts of a teleutospore 

 become completely disunited. Most of the cells possess three 

 germ-pores, which, when situated near the transverse septum, 

 frequently alternate with those of the second cell (Fig. 90). 



