166 DISEASES OF TREES 



between these two fungi, and this I was able afterwards to 

 confirm. At the same time I proved that M. Tremulce produces 

 Cceoma Laricis on the larch. 



Then Rostrup also obtained Cceoma Mercurialis by infection 

 with M. Tremulce. Rathay believes that he has also obtained 

 ALcidium Clematitis on Clematis vitalba by infection with spores 

 of M. populina. 



As regards Cceoma pinitorquum and C. Laricis, I obtained the 

 aecidia of both by infection with sporidia from the same aspen-leaf^ 

 and, further, I have infected Pinus with teleutospores of Melamp- 

 sora which I had raised by- sowing Cceoma Laricis on the aspen. 



Thus, although it appears to me that the identity of these 

 two species of Cceoma has been conclusively proved, still it 

 would be desirable to have this confirmed. Even more pressing, 

 however, is the solution of the problem whether Cceoma Mer- 

 curialis also originates in the same species of Melampsora, or 

 whether various species occur on the aspen to which these 

 aecidium forms belong. Further, it is necessary to discover 

 whether the species present on P. nigra, P. alba, and P. bal- 

 samifera are identical with those on the aspen ; and, finally, it 

 remains to be determined whether the aecidium forms possess a 

 facultative character, as appears to me most probable. I have 

 described below the two diseases produced on conifers by M. 

 Tremulce. 



First Form on Pinus sylvestris with Caeoma pinitorquum. The 

 Pine Shoot Twist Disease. Melampsora Tremulae pinitorquum 



This disease is distributed throughout the whole of Ger- 

 many, being most prevalent in the north, where it has proved 

 exceedingly destructive, especially from 1870 to 1873. It may 

 attack young pine seedlings even at the stage when they are 

 just appearing above ground. In such a case longish pale 

 yellow sporogenous layers rupture the epidermis and appear 

 upon the surface of the stems or leaves. The disease is most 

 frequently observed in pine woods from one to ten years old, 

 infection being brought about by the teleutospores of M, 

 Tremulce which develop on aspen- leaves that are lying about on 

 the ground. The disease may be recognized by the fact that in 

 the beginning of June, sometimes even in the end of May, at the 



