Jan. 14. 1918 Cultures of Wood-Rotting Fungi on Artificial Media 63 



of these three fungi. The cultural differences between P. texanus and 

 P. dryophilus are much more marked than those between P. farlowii 

 and P. dryophilus. A study of the tables giving the characters of these 

 three fungi at once shows marked and constant differences between each 

 . of the three species. It will be seen that general color resemblances are 

 not as distinctive in differentiating specific characters as are certain 

 other factors. Many of these species have a buckthorn brown color on 

 several of the agars, which indicates their general relationship while 

 specific characters must be sought in the differences of growth on certain 

 agars. 



The difference in the fruiting of related species on the various agars is 

 also of much value in differentiating species. For instance, P. farlowii 

 fruits vigorously on several of the ten culture media producing perfect 

 and typical pores, P. dryophilus very rarely fruits on the culture media 

 here given unless the inoculum is fresh sporophore tissue, while P. texanus 

 has so far fruited on only two of them. 



IDENTIFICATION OF UNKNOWN ROTS BY CULTURAL CHARACTERS 



The cultural character method here given can be used to determine 

 what fungus produces a given rot. In a large majority of cases rots, 

 both heart and saprophytic, will be found without any sporophores 

 being present to indicate what fungus produced the rot. If careful 

 inoculations are made from such infected wood, it is a comparatively 

 easy matter, as a rule, to obtain pure cultures of the causative organisms 

 and later grow them again on the 10 media given, thus determining their 

 cultural characters and from them the fungi producing the rots. 



The number of species of fungi producing heartrots in living trees is 

 not very great. A few of them produce rots which can usually be 

 identified by the character of the rot alone, such as Trametes pini, but 

 the great majority of them can not be certainly determined by the rot. 

 For instance, the rot produced in conifers by Polyporus schweiniizii, 

 P. stUphureus, and Fonies laricis are so similar that no one can be certain 

 by examining the rot alone which of these three fungi was the cause of 

 the rot in question. 



The rots of structural timbers are more numerous than the true 

 heartrots and the causative organism producing each rot is more difficult 

 to determine from the rot alone, since the majority of the structural- 

 timber rots are very similar in general appearance. Most of these rots 

 are of the carbonizing type, where a brownish, brittle rot is produced 

 which on dessication breaks up into little cubical blocks of varying sizes. 

 Pure cultures from these structural timber rots will differentiate them 

 as to their causative organisms at once. The value of such means of 

 determining the causative organism from the rot in the absence of any 

 sporophore is very evident to anyone who has had to deal with such rots. 



