366 



URKDINEAE. 



in shape, yellow in colour, and their outer coat is beset with 

 spiny projections. The stalk-cells grow ont into elongated tubes, 

 after completion of spore-formation. In the vicinity of the 

 scar of a Caeoina--pntch, the twig turns brown and its tissues 

 become permeated with resin, while the tissues underlying the 

 patch die even into the pith. 



Hartig's ^ investigations show that this same Melamjjsora causes 

 Cacoma laricis on the needles of the larch. Plowright - also 

 produced a similar Caeoma-tonn from Mclami^sora hctulina, and 





Fio. 198. — Melampsora betulina. Teleutospore-sorus, with many of the sjiores 

 producing promycelia and sporidia (s). r, Mycelium ; p, parenchyma ; c, portion 

 of ruptured epidermis. (After Tulasne.) 



succeeded in re-infecting Bctula alha from Cacoma laricis. 

 Rostrup obtained Cacoma mereurialis by infecting Mercurialis 

 with Mel. trcmulae ; yet this may have happened because two 

 different species of Melam.psora occurred on the aspen leaves. 

 Klebahn ^ was successful in infesting Popvlvs tremtda with 

 Cacoma laricis but did not succeed with the birch. 



1 R. Hartig, AUei/em. Forst. u. Jagd-zeittmg, 1885, 



-Plowright, " Impfversiiche m. Rostpilzen," Zeitschrifl f. PJlanzenkrankheiten, 

 391. 

 •■'Klebahn, Zeitxchrift f. PflanzenkranUmtei} , 1894. 



