﻿ATKfXSOX~COPRI.XLS 



right when he said in regard to the origin of the lamellae of C. lagopus 

 that they arise as new, free vegetation points on the under surface 

 of the pile us and continue through apical growth (12, p. 127). It 

 should be said, however, that growth continues throughout the 

 width of the lamellae and of the palisade layer. 



Besides the clear evidence just presented as to the origin of the 

 lamellae in C. micaceus, there are other considerations which sup- 

 port the conclusion just arrived at. These are (1) the method of 

 origin of the secondary lamellae; (2) the lack of fundamental ele- 

 ments in the trama; and (3) the freedom of the primary and 

 secondary lamellae, under normal conditions, from each other, 

 during all stages of development. 



Origin of secondary lamellae.— By "secondary" lamellae 

 is meant those which arise later than the primary or first lamellae. 

 The secondary lamellae are the shorter ones which are inserted in 

 the space formed by the divergence of the primary ones as they 

 extend farther from the stem. Because of the centrifugal growth 

 and organization of the pileus, young hymenophore, and gill origins, 

 by which the younger, or later, origins of these morphological ele- 

 ments appear successively in a centrifugal direction, and thus 

 farther and farther from the stem, it will be seen that the secondary 

 and later lamellae originate later than the primary ones, provided 

 they are appreciably shorter than the latter. In comparatively 

 young basidiocarps cross-sections of the hymenophore with young 

 lamellae usually show that the secondary lamellae are narrower 

 throughout their entire length than the primary lamellae. Some 

 of them later become connected with the stem, while others do not. 



A series of tangential sections perpendicular to the lamellae 

 and parallel with the axis of the stem, in a comparatively young 

 basidiocarp, the knife traveling away from the stem toward the 

 margin of the pileus, will show the origin and different stages of 

 development of a secondary lamella. The ends of the secondary 

 lamellae toward the stem are arrested in development because the 

 space is here more cramped than farther away where the primary 

 lamellae are farther apart. Figs. 56-61 are from 6 such serial sec- 

 tions. A "landmark," or indicator, was selected, so that in mak- 

 ing the photomicrographs the two primary lamellae between which 



