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THE ROYAL SOCIETY OF CANADA 



wood. However, in 1865, Thomas (13) and later, in 1871, Von Mohl 

 (10) expressed the view that it was a derivative of parenchymatous 

 tissue. Moreover, in 1890, Daguillon, after an extensive study of the 

 foliar conditions of the Abietinese came to substantially the same 

 conclusion, in that he evidently considered transfusion tissue of 

 pericyclic origin. DeBary (1) in 1877, and Lignier (9) as late as 



Fig. 2. — Cordaites principalis. 

 [Long, radial section of leaf bundle — Stopes after Jeffrey (7.).] 

 • cp. — Centripetal xylem. 



i.s. — Inner transfusion sheath. 

 O.S. — Outer transfusion sheath, 

 px. — Protoxylem. 



1892, formed the opinion that it might have been developed in replace- 

 ment of a reduced foliar venation. A few years later (1879) after 

 considerable careful study along this line, Worsdell (16) came to the 

 conclusion that transfusion tissue was "phylogenetically derived from 

 the centripetally formed xylem of the vascular bundle." Bernard's (2) 



Fig. 3. — Prepinus statenensis. 

 Transverse section of leaf bundle — Jeffrey 7. 

 b— Bast, 

 cp. — Centripetal xylem. 

 cf. — Centrifugal xylem. 

 i.s. — Inner, o.s. — outer, transfusion sheath. 

 px. — Protoxylem . 



