366 



UREDINEAE. 



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

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

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

 scar of a Caeoma-patch, 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 Melampsora causes 

 Caeoma lands on the needles of the larch. Plowright ^ also 

 produced a similar Caeoma-iorm from Melampsora betuliTia, and 





& 



Fto. 198. — Melampsm-a betulina. Teleutospore-sorus, with many of the spores 

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

 of ruptured epidermis. (Aiter Tulasne.) 



succeeded in re-infecting Betula alba from Caeoma laricis. 

 Eostrup obtained Caeoma mercurialis by infecting Mcrcurialis 

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

 different species of Melampsora occurred on the aspen leaves. 

 Klebahn^ was successful in infesting Populits tremula with 

 Caeoma laricis but did not succeed with the birch. 



'R. Hartig, Allegtm. Forst. u. Jagd-zeitung, 1885. 



^Plowright, " Impfversuohe m. B.ost]>i\zen," Zeitschri/t /. PJlanzenh-ankheiten, 

 1891. 

 ' Klebalin, Zeitschrift f. Pflanienhrankheiten, 1894. 



