1922] Essig: Morphology of Schizophyllum commune Fries 467 



downward. At the end of 17 days a normal sporophore about 1 cm. 

 in diameter had developed (fig. 2, pi. 60). 



In another experiment the entire hymenophore was removed by 

 cutting across the stipe at the distal end. Specimens left in the orig- 

 inal position produced new hymenophores in one of two methods. If 

 the stipe was small at the cut end, only one new sporophore, as a rule, 

 developed by the growth of hyphae out through the cut end of the 

 stipe (fig. 3, pi. 60). This developed in the usual way. If the cut 

 end of the stipe was of considerable area, several small sporophores 

 developed. These grew in the usual way except that the hymenial 

 plates arose in position with respect to the old stipe and not as though 

 the separate sporophores were distinct individuals (fig. 18d, pi. 52). 

 The sporophores more advantageously placed, that is, at the upper 

 edge of the stipe, grew more rapidly and became much larger than 

 those at the sides. The sporophores might be cut away to within a 

 millimeter of the base of the stipe and still a new sporophore would 

 develop upon the cut end. The specimens used were mature and were 

 shedding spores, but were comparatively young. Thus the sporo- 

 phores have, at least while still young and fresh, the ability to regen- 

 erate practically the entire body. 



Stipes with the entire hymenophore removed and in an inverted 

 position in all cases produced either one or several small sporophores 

 upon the cut end, but growth soon ceased. Sections through these 

 specimens showed that thej' had stopped growing either in the 

 "peziza" stage or after one or two hymenial plates had been formed 

 (figs. 19-20, pi. 52). The inability of the sporophores to develop 

 further in an inverted position is doubtless due to their lack of power 

 to change the polarity of the different parts with respect to the 

 reaction to the force of gravity. That gravity is the form-stimulus 

 was clearly demonstrated by Hasselbring (1907). 



4. EELATION OF THE MYCELIUM TO CELLS OF DEAD WOOD 



Upon sectioning dead wood it is found that there is an unexpected 

 paucity of mycelium in the tissues infected by Schizophyllum. Wood 

 brought in from the field in a dry condition covered with the sporo- 

 phores may be sectioned and fail to display any mycelium in a large 

 percentage of the sections. In some, however, a few hyphae can be 

 seen. 



The hyphae of this fungus are shown by sections to be confined 

 almost entirely to the tracheae of the wood (pi. 61). In some ducts 



