362 
Proceedings of the Royal Society of Edinburgh. [Sess. 
horizontal portion, the section here passing through the junction of the 
lamina and sporophyll-base. One sporophyll has been cut across at a 
slightly higher level, and is not traversed by the section throughout its 
length. It shows the transversely widened pad of tracheidal tissue forming 
the sporangial stalk ( sp . a). Between these sporophylls of the whorl b 
appear the summits of sporangia belonging to a lower alternating whorl 
( c ). Reference to the plane of section B B indicated on fig. 1 will show that 
these sporangia are bulging up into the mucilaginous bases of the whorl of 
sporophylls a. These sporophyll-bases have been traversed at the level 
of their lower horizontal surfaces. The outer persistent portions of these 
sporophyll-bases (a) are cut through, but being here traversed at the level 
common to them and to the sporophylls of the alternating whorl below ( b ), 
are not free as in fig. 3. In fig. 4 they are seen to be continuous with the 
sporophylls between which they stand. If the tissue of the lower surface of 
the sporophyll-base a had persisted, this continuity would be apparent as a 
web of tissue connecting the sporophyll-bases of the whorl b from their 
proximal to their distal end. Since, however, only the outer margin of 
the sporophyll-base a is composed of persistent tissue, the continuity appears 
as a band connecting the sporophylls below (b) at the junction between the 
sporophyll-base and the lamina. 
The evidence afforded by the sections described shows that the 
sporophyll-bases in L. cernnnm are coherent to a short distance further out 
than the place of attachment of the sporangia. This conclusion has been 
fully confirmed by the study of sections of cones of different ages. A little 
consideration will make it clear that, when dealing with a mature cone, 
only three planes of section will afford evidence of continuity of persistent 
tissue (as contrasted with that shown by the membrane bounding the 
mucilaginous sporophyll-base). These three sections are : — 
1. A transverse section at the level of the pedicel-like persistent portions 
of the sporophyll-bases of one whorl ( b ) and the lower limit of the sporo- 
phyll-base of the whorl above (a). (Cf. the plane B B in fig. 1, and fig. 4.) 
2. A tangential section close to the periphery of the cone and passing 
through the persistent tissue of the abaxial surface of the sporophyll-bases. 
3. Sections slightly removed from the radial plane, showing the margin 
of the lamina of one sporophyll connected with the lower margin of the 
sporophyll-base of the whorl above. (Cf. the lowest complete sporophyll on 
the right-hand side of fig. 1, where this continuity is nearly shown.) 
Were the mucilage wholly removed from the cone, the fact that the 
sporophyll of L. cernuum is not composed of a free subcylindrical pedicel 
bearing a large peltate lamina would only be shown by the continuity of 
