196 N. TAX AK A. 



-sustain its life. In the state just described no fructification of the 

 fungus is yet observable, although its subterraneous vegetative 

 mycelia are actively growing. 



After the fungus has Ijeen growing in this manner for some time, 

 flat irregular disks of mycelia begin to form under certain circum- 

 stances on the aerial portion of the tree at the bases of the shoots. 

 These disks are the first stages of the |)ileus. The successive stages 

 -of growth of the pileus are shown in Plate XXIV, Figs. 2, 3, and 

 4. It first appears as a thin etfused mass of mycelia of a dark purplish 

 brown colour, haviug a paler margin of definite outline, and present- 

 ing a smooth velvety appearance (PL. XXIV, Fig. 2, a). It surrounds 

 the basal [)art of the shoots of the diseased tree to a height of 15 

 cm. or more, sometimes leaving here and there small narrow portions 

 unG<wered. It often encloses in its embrace some extraneous matter, 

 such as decayed leaves, branches, and the like, together with particles 

 of soil. As it gradually develops, it forms generally an irregular 

 r(3undish flat disk, one part of which stands out at right angles from 

 the surftce of the shoot, while the other remaining part is firmly 

 attached to it. The projecting part of the [)ileus then expands 

 laterally either on one side of the shoot or on both sides ; and as the 

 shoot is usually bent horizontally at the base, the pileus becomes also 

 horizontally expanded. The hymenium is produced on the free sur- 

 face of the pileus, on the u{)per and lower sides of the projecting 

 parts, as well as on the exposed side of the part fastened to the shoot. 

 The fully developed pileus is of a whitish colour tinged with violet ; 

 the projecting part is about 5 mm. thick, and its upper surface is more 

 uneven than its lower surface (PL. XXV, Figs, 1, 2). 



By carefully detaching the young pileus from the substratum, 

 numerous mycelial strands of unequal thickness may be observed on 

 its lower margin (PL. XXV, Fig. 3). These strands are found on 



