TELEUTOSPORES 



11 



both (Fig. 12). The uredospore retains its capacity for 



germination for a longer time, even 



for more than three months ; in fact, 



in certain foreign species, some of these 



spores acquire a thicker wall which 



enables them to act as a kind of 



resting-spore — these are called amphi- 



spores, but they are not formed by 



P. Caricis. 



It is found, generally, that if the 

 spores of the Uredinales are dried 

 gradually, they retain their power of 

 germination for a longer time and in 

 a better degree than if dried quickly 

 or not dried at all. Most likely a slow 

 drying enables them to mature more 

 perfectly. 



Fig. 12. Two uredospores 

 of P. Caricis, both germi- 

 nating in distilled water. 

 xl80. 



The Teleutospores. 



After a time, probably in response to the weather or other 

 change of environment, the mycelium which has hitherto given 

 rise only to uredospores begins to produce, at first in the same, 

 afterwards in separate sori, the fourth kind of spore — the 

 teleutospore. In the genus Puccinia this is almost always a 

 compound body, formed of two superposed cells ; each cell is 

 really a spore, and is capable of independent germination. In 

 many species of the genus the teleutospores readily break 

 apart at the septum, e.g. in Puccinia fusca and P. Pruni- 

 spinosae, and the lower half may be, and has been, mistaken for 

 a uredospore. Those of P. Caricis do not easily break apart 

 until they are old and dead. 



The teleutospores are formed on a pedicel, much in the 

 same way as the uredospores, except that the uppermost cell 

 is again divided, but apart from that they differ widely in 

 their character. They have a thick dark-brown exospore, 

 covered with a chitinous cuticle ; in this species the exospore 



