m 



FIG. 111. R, stem of Zamia fioridana ; S, central cylinder of same; T, cortical foliar 

 bundle of Cycas revoluta ; l\ petiolar bundle of same ; F, section of part of leaf of a 

 species of Cordaites; W, cotyledonary bundle of Ginkgo biloba: px, protoxylem ; 

 x 1 , centripetal wood ; a; 3 , centrifugal wood. 



