﻿BOTANICAL GAZETTE 



results from the change in the relative position of the pileus during 

 its growth, the pileus after a time approaching a position nearly 

 or quite parallel with the axis of the stem. Figs. 23 and 24 are 

 from sections perpendicular to the stem axis. 



Attachment of the lamellae to the stipe.— Before the 

 plants are fully mature the margins of the lamellae become attached 

 to the stipe. The age of the lamellae when this attachment takes 

 place probably varies in different plants, and even in the same 

 plant, depending on the size of the annular gill cavity and the 

 distance which the lamellae must grow in width before the margins 

 come in contact with the stipe. For example, in some cases the 

 younger portions of the lamellae at the extreme margin of the pileus 

 may become attached to the stem before the older portions do, 

 because of the narrower space between the margin of the pileus 

 and the stem and the cramped situation in which the lamellae 

 are immediately following their origin or at the time of their 

 origin. Where the gill must cross an open space before it comes 

 in contact with the surface of the stipe, the edge is evenly rounded 

 and furnished with the closely parallel clavate cells forming the 

 palisade layer which is continuous with the similar palisade layer 

 on the sides forming the hymenium. When the lamellae come in 

 contact with the stipe they press more and more firmly against it 

 as growth continues. This pressure tends more and more to spread 

 many of the palisade cells of the margin laterally, and thus bring 

 the trama cells more or less in direct contact with the surface of the 

 stem. This is well shown in fig. 23, where the three lamellae 

 show different phases of this process. The one at the left shows 

 the strong spreading of the marginal palisade cells with trama 

 hyphae in contact with the stem. In the middle one the marginal 

 cells are only partially spread, there being in this section two clavate 

 cells which still keep the trama hyphae separated from the stem 

 surface. In the lamella at the right the marginal cells have only 

 just begun to spread laterally. 



While the marginal cells of the lamellae are thus spreading 

 laterally, and afterward, a few of these cells as well as branches 

 from the trama hyphae, by growth, interlace more or less with the 

 loose open plectenchyma of the stem surface and the junction is 



