x] ROOTS. 347 



diagrammatically sketched in fig. 92 illustrates very clearly the 



Fig. 92. Tangential section through a node of Calamites^ showing a root in 

 organic connection with the stem. 

 R, R'. Root (Astrornyelon) in transverse and oblique section, x, xylem ; 



m, primary medullary ray ; t, leaf-trace ; s, Stigmarian appendage. 

 R", the inner portion of one of the xylem wedges of R' more highly magnified. 

 Sketched from a section in the Cambridge Botanical Laboratory Collection. 



