AUTOBASIDIOMYCETES 461 



On the oak and other deciduous trees the mycelium is much 

 more dense than in the spruce, for example. In the latter the 

 mycelium is said to be colorless. It is, however, in some instances, 

 slightly cream colored when approaching the surface. Hartig 

 has mentioned the appearance of a secondary fruit form in the 

 oak. This also occurs upon other hosts, and cultures from frag- 

 ments of the sporophore have promptly given, on various culture 

 media, a vigorous cream colored mycelium, which with age becomes 

 mealy in appearance, due to the extensive formation of conidia, 

 such as are referred to above. These conidia correspond to those 

 which are considered by Brefeld to be the typical oidial stage 

 frequently present in Hymenomycetes. 



The sporophores of this species appear usually during the late 

 summer or early autumn, in large, shelving clusters (Fig. 226) or 

 sometimes scattered. The form of the pileus may be considerably 

 modified by its position upon the host and by its relation to other 

 sporophores. The sporophore is fleshy and of a cheese-like con- 

 sistency when young, becoming harder and woodier with age. At 

 first the entire sporophore is yellow, but later the under, pore-bearing 

 surfaces are bright yellow, while the upper surfaces are ordinarily 

 orange-red. The flesh is at first white, becoming slightly cream 

 colored with age. These sporophores may grow in such masses 

 as to attain a length and height of from 30 to 40 cm. The in- 

 dividual pilei may be entirely sessile or slightly stalked, and loosely 

 scattered or so closely massed as to be united in the vicinity of the 

 host. The young plants have a distinct odor, which becomes pro- 

 nounced with age. The pores are found on the under surface 

 only. They are about 4 mm. deep, with nearly circular outlines. 

 The spores are hyaline, ovoidal in outline, and usually measure 

 7-8 x 4-5/4. 



Control. In controlling this fungus the only practical measures 

 are to cover up as promptly as possible with tar or other antiseptic 

 materials all wounds, either natural or as a result of pruning, and 

 further, to destroy all sporophores as they appear. The spores de- 

 velop very quickly after the sporophores are mature, and it is very 

 probable that their distribution is effected by means of insects, 

 which may be attracted by droplets of a sugary substance which 

 may accumulate on the under surfaces of the sporophon 



