THE DISEASES OF C0XIFEK3. 



133 



o£ leaf-casting. Herpotrichia nigra^ causes a tiresome disease 

 on Pinus montana, and also on tlie Spruce and Junipers at 

 high altitudes. Hysterium hrachysporum kills the leaves of 

 the Weymouth Pine, and Farlow and Seymour t give a long 

 list of American forms that will necessitate much careful in- 

 vestigation before we can determine which are truly parasitic 

 and which merely saprophytic. 



There is in Germany a disease of the Scotch Pine known by 

 a name which I may translate the Pine-twist." Its prominent 

 symptoms are contortions and curved malformations of the tips 

 of the leading shoots, caused by the invasion of a fungus known 

 as CcBoma innitorquum. The hyph^e of this parasite so torture 

 the epidermal region of the young shoots that their growth in 

 length is no longer equal on all sides ; considerable deformity 

 may result from the curvatures of the healthy parts about 

 the dead infested regions, and even the death of the tips 

 occurs in bad seasons — i.e., seasons too wet for the Pine, but 

 very agreeable to the fungus. In dry summers, however, the 

 fangus-layers may die off, and the injured spots be occluded. 



Robert Hartig, in 1874, showed that this CcBoma ijinitor- 

 quum is merely the acidial form of a fungus long known as 

 Melampsora Trcmulce, and which develops its Uredo- and 

 Teleuto-spores on the Aspen and other Poplars. 



Plowright failed to confirm Hartig's results with these fungi, t 

 Hartig found, moreover, that a certain disease on the leaves of 

 the Larch is also connected with the above 2Ielanipsora, and this 

 was also confirmed by Plowright. But since the latter observer 

 has now repeated the infections, and confirmed Hartig's ob- 

 servation so far as the Larch is concerned,§ we are justified in 

 hesitating before we reject the view put forward above. It is 

 interesting (and also important! to see, moreover, that Plowright 

 has shown that Melamiosora Betuliiia, on the Birch, infects the 

 Larch with the same disease as does 21. Tremulce.'^ 



Perhaps there are two species of Melamjosora here concerned, 

 both of which infect the Larch ; or it may be that the CcBoma 



* E. Hartig, " AUgem. Forst. u. Jagd-Zeitung," January 1888. 

 f "A Provisional Host-Index of the Fungi of the United States," 

 Part m., 1891, pp. 160-166. 



I "Brit. Uredineffi and Ustilaginese," 1889, p. 241. 



§ " Zeitschr. fiii- Pflanzenkrankh.," 1891, B. i., H. 3, pp. 130, 131. 



II Loc. cit., p. 131. 



