60 Alfred J. Ewart : " BI ad- fellow s BrearU 



the pot had remained the whole of the time, within two days 

 white pustules appeared, these developino' from cracks on the 

 side and upper surface af the sclerote. In four days one of 

 these developed into a large Pohjporus fructification, 5 inches 

 in diameter, with a somewhat irregular margin and a. short stalk, 

 and two additional small outbreaks of pustules developed later 

 to similar fructifications. On a darkened portion and on the 

 under surface, no development of fruits took place. The power 

 of developing a hymenium is not confined to the surface of a 

 sclerote, for spore-bearing tubes may develop directly from the 

 central portion of the fruit when this is cut in two. Mr. 

 McAlpine noted that on the under side of a slice, groups of 

 tubes formed on the surface, without any properly stalked fruit 

 body being produced, whereas on the upper surface, a normal 

 sporophore appeared. He concluded that the former peculiarity 

 was due to the fact that on the under surface, the formation of 

 a sporophore was physically impossible. This is, of course, not 

 the case, for many fungi will develop sporophores when the 

 rudiment starts in the inverted jDOsition, the stalk usually 

 bending so that the pileus or cap is developed in the normal 

 position. Similarly, the sporophores of Polyporus are able to 

 develop against far greater pressures than would be represented 

 by the weight of a slice of the sclerote. Actual experiments 

 showed that the same formation of groups of sessile tubes, 

 instead of a stalked sporophore, took place on slices placed with 

 their cut surface vertical, Avhere there was no physical resist- 

 ance to the formation of a stalked sporophore. Evidently, 

 therefore, neither the influence of gravity nor that of light can 

 be responsible for the non-formation of the usual regular stalked 

 sporophore in such cases. Apparently, cutting the sclerote into 

 slices produces a profound disturbance in the morphogeny of the 

 sporophore, which usually breaks through cracks in the outer 

 surface. The removal of the mutual pressures exercised by the 

 central tissues at the cut surface as well as the cessation of 

 their reciprocal formative or inhibitory influence on the free 

 surface at least, probably leaves each part of the exposed surface 

 free to exercise its spore forming tendency in the most direct 

 possible manner, which is by the immediate formation of 

 hymenel tubes without the intervention of a sporophore. 



