INJURIES INDUCED BY PLANTS 179 



CHRYSOMYXA LEDI l 



This parasite induces the same pathological symptoms in the 

 spruce as the preceding one, but it differs in producing its teleu- 

 tospores and uredospores on the leaves of Ledum palustre* 

 Letters received from Russia mention that the fungus occurs in 

 extraordinary abundance in that country, and I have also recently 

 had it forwarded from the district of Konigsberg. It has also 

 frequently been observed in other parts of Germany, with the 

 exception of the south, but of course only where Ledum occurs 

 in the immediate neighbourhood. 



In the case of the parasites about to be described, the eecidium 

 forms alone are as yet known, so that the investigation of the 

 course of development of what are probably all hetercecious 

 forms of fungi is work for the future. 



ISOLATED ^CIDIUM FORMS 



From amongst the aecidium forms of whose teleutospore-forms 

 we are so far ignorant, attention will here be directed only to 

 those species which occur on forest trees. 



(PERIDERMIUM) ELATiNUM 2 f 



This fungus is parasitic on the silver fir, where it produces the 

 so-called witches' brooms and canker-knobs which may be seen 

 anywhere in Germany where woods of silver firs occur. 3 As I 

 have always noticed small wounds on one- or two-year-old 

 witches' brooms close to their base near the point, namely, where 

 they have developed from a bud it may in the meantime be 

 assumed that infection occurs at such wounds. The mycelium 

 of the fungus, which stimulates growth in a very marked manner, 

 is perennial in the cortical and bast tissues of the stem, and even 

 penetrates the cambium and the wood. Should infection occur 



1 De Bary, Bot. Zeit., 1879. 2 Ibid., 1867. 



[ 3 Very common also in many parts of Britain, e.g. the south-west of 

 Scotland. Trans.] 



*[An Ericaceous plant found on moors, &c., in N.E. Europe. ED. ] 



t [The cankers occur in various Silver Firs grown in English gardens, 

 though they often seem devoid of the Witches' Brooms and aecidia. I have 

 seen both, however, on Abies Pinsapo and other species. ED.] 



N 2 



