88 EQUISETUMS AND CALAMITES. 
Calamites which I have neater as sclerenchymatous, but apparently 
forming part of the fibro-vascular bundle, to be sclerenchyma, the 
necessity for considering the gore decorticated at once disappears, 
These woul 
ting in the underground stems, hence the dnhitinated appearance 
usually ascribed to them 
hat part does the sclerenchyma, which forms so important a 
constituent of the at of other vascular Cryptogams, play in the 
construction of Cala 
In Ferns the slorenchyma i islargely developed. In Pteris pee 
it forms two well-marke migrate plates between the fibro 
vascular bundles, and also forms a thick zone under the epidermis, stot 
complete, but defective along tie lateral lines. — small scleren- 
chymatous bands are scattered between the bun In Tree Ferns 
Williamson’s interpretation of the Calamite stem be correct, then no 
pe vtagg ed exists, orif it did exist it has been lost with the missing 
©! supposition, however, can hardly hold good, because 
the salebelintiyats was as likely to be preserved as any other part, ~ 
as it forms a more or less complete investing cylinder in most case 
wo! certain to have the Slto-rdaaliar 
s, unless removed by face sufficient to have destroyed the more 
delicate internal tissues. The conclusion that forces itself on me is 
chyma, which must be perforated by the tissues run ning to a branch or 
leaf ; or that agen oe Figen has taken place in the bundle 
after hae ie ch was a 
called woody-cylinder i in that baaaas and in whieh? Prof. * Williamson 
eemete hi bent discovered circumferential Eryw it _pne pointed base 
cones Punaiickite Schriften, Dp. 138. 
+ Phil. Trans., plate, xxiv, 
