196 MODERN FOREST ECONOMY. 



development, do damage as parasites to the plants which 

 supply to them a lodging place. 



' The Peridermium pint, Lev., or Kiefern-Masenrost, and 

 the P. oblong{sporinm,Fvic]iL., or Kiefern-nadelrost introduce us 

 to the kinds spoken of; both stand in the nearest relation- 

 ship to one another, and are treated by many students as 

 of the same species,' A discussion of their specific charac- 

 ters would lead us too far at present; and the author 

 considers it preferable to treat them in his work as dis- 

 tinct species. ' The habitat of both is pretty well known 

 to every forester ; everywhere are they of no rare appear- 

 ance, both in forests of the white and of the black pine. 

 Only is injury done, or can be done, by the Kiefer-Uaserv- 

 rost, when it comes upon the branches or trunks. It kills in 

 young woods many young trees, and it produces rents in 

 the trunks of old pines, when it finds a home either within 

 or below the crown, producing the well-known appearance 

 of the Krebses or Kienzopses. The Coleosjporiuw, senecionis, 

 Lev., found upon different species of Senecio, it is generally 

 admitted, is a peculiar propagator of both species of Peri- 

 dermium, and no further investigation of the fact appears 

 to be necessary here ; nor is it necessary to discuss further 

 the innumerable well considered measures for the preven- 

 tion and destruction of this fungus which have been 

 proposed. 



' Postia (Polyporus) destructor, Thuem, the Zersioerende 

 Loecherschwamm, vegetates abundantly on wood work in 

 dwelling-houses, damp cellars, stables, manufactories, old 

 palings, and especially on wood which has been for a long 

 time exposed to the influence of humidity. As it by no 

 means rarely grows in shady forests on the bark of firs, 

 pines, and black pines, and this not only when they are 

 felled or dead, the conclusion come to by some seems to 

 be justified, that the infection takes place in the forest ; 

 and that when, at a later time, the wrought wood comes 

 into an atmosphere heavily charged with moisture, with 

 limited access to the open air, the mycelia to be found in 

 the body of the wood produce a new fructification. The 



