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XIV. The Comparative Anatomy of certai^pecies 0/ Encejolialartos, Lelw). 



By W. C. WoR^LL, F.L.S. 



(Plate XLIII.) 



Read Kith November, 1899. 



IHERE may be said to be two types of structure prevailing in the stems of the 

 Cycadacese — viz., the one in which there occurs a single vascular cylinder, as in 

 the majority of Dicotyledons ; the other in which there is more than one cylinder, often 

 as many as a dozen. There are three genera which present this last type of structure,. 

 viz., Cycas, Macrozamia^ and Encephalartos. Of these, the first two have already been 

 worked out and described in detail ; the third, although the main features of its structure 

 have been superficially touched upon and referred to, has yet to be treated in the same 

 way as the others have been. This detailed account of the structure I propose giving in 

 the following pages. 



Historical Survey. 



Mohl * in his paper, " Ueber den Bau des Cycadeenstammes," shortly describes the 

 structure of Encephalartos under the generic name of " Zamia." He distinctly mentions 

 the occurrence of the medullary system of bundles, and states that of a second vascular 

 cylinder there are only very inconspicuous traces. The species described by him under 

 the old generic name were Encephalartos latifolia and E. horrida. 



Miquel's monograph f includes many species of Encephalartos, but, naturally, very 

 little information as to the anatomical structure is given. 



Mettenius %, in his excellent work on Cycadean anatomy, treats briefly of the principal 

 features of the stem-structure of Encephalartos, as also of Cycas^ Eicon, and Zamia 

 tnuricata. 



Encephalartos catfer, Lehm. 



General Structure. 



Having obtained from Mr. Wm. Bull, of Chelsea, an old plant of Encephalartos caffer, 

 Lehm., with a stem about 9 inches in diameter, I was enabled to carefully investigate its 

 anatomical structure and to compare it with that of Cyca^ and Macrozamia. I have 

 found the structure to be extremely similar to that of the latter genus— so similar, in 



* Abhandl. der konigl. baj-. Akad. zu iliincbcn, i. 1832, pp. 397-442 ; republished and revised in ' Vermischte 

 Schriften/ 1845, pp. 105-2 U. 



t Monographia Cycadearum, 1842. 



t "Beitriige zur Anatomic der Cycadeen," Abhandl. der kiinigl. sachs. Gesellsch. der Wiss. vii. 1801, pp. 565-609. 



SECOND SERIES. — BOTANY, VOL. V. 3 Y 



