﻿4 TKI.XSOX — L ( »/'A7_\ / V 



97 



It seems almost needless to state how the presence of a general, 

 annular, prelamellar cavity is determined, when the fundamental 

 principle of determining not only the extent, but the continuity and 

 conformation of structure by serial sections, is so generally known ; 

 but inasmuch as the presence of such a cavity in the development 

 of any of the Agaricaceae has been denied, it may be stated that 

 its presence has been determined by serial longitudinal sections of 

 basidiocarps, that is, sections parallel with the axis of the stem. 

 Beginning on one side of the basidiocarp, 1 ? q 

 as the sections enter the region of the 

 annular cavity, there is but one cavity 

 in each section which is more or less 

 transversely elliptical in form. As the 

 sections pass through the stem, there 

 will appear two cavities symmetrically 

 placed, one on either side of the stem; 

 then as the sections pass beyond the 

 stem through the opposite side of the 

 basiodocarp, there is but one cavity, as 

 on the entering side (see diagram I). 



Origin of the lamellae. — Coprinus 

 comatus is an exceedingly interesting 

 form in which to study the origin of the ™ e ul ^ n s ^ n ^ty similar 1 to 

 lamellae. The ''posterior" ends of the ^ in sect ions at i; B, zenith 

 lamellae are not only "free" from view through same, showing 

 the stem, but they are quite distant from J^* 011 ^ 0 * seTfigT 

 it. In their origin, therefore, the ques- T^^^' ~' ^ 3 ' ^ gS " 

 tion is not complicated by certain diffi- 

 culties sometimes met with in studying the origin of lamellae which 

 are "adnexed " or "adnate," or even where they are free at maturity 

 but very close, or adnexed, to the stem in the very young stages. 

 In C. comatus there is a circular area on the under surface of the 

 pileus immediately surrounding the apex of the stem, over which 

 the fundament of the hymenophore is not formed, at least in all the 

 specimens which I have examined thus far. This accords with the 

 earliest formation of the palisade layer, which, as previously stated, 

 begins at some little distance from the stem and then proceeds 



rnmetrically disposed, 



