6 o 2 WorsdelL — Anatomy of Stein of Macrozami a 
concluding that wood only is formed in this stem. His 
paper, however, is interesting and valuable, from the fact 
that he was the first to point out the real gymnospermous 
character of these stems and to refute the old idea of the 
similarity of their structure to that of Monocotyledons. 
Von Mohl, in his paper ‘ Ueber den Bau des Cycadeen- 
stammes 1 / gives a considerable amount of detail about the 
structure of the stems of Cycas and two species oi‘ Zamia' 
{Z. latifolia and Z 7 . horrida ). He states that in the pith of 
his Zamia latifolia there are a number of reticulately-united 
bundles, with scalariform or bordered pits, which pass singly 
through a medullary ray to the cortex. On the subject of 
anomalous thickening he says, speaking of Cycas , that some 
bundles from the normal ring pass out and run downwards 
through the cortex, arranging themselves side by side to form 
a second outer ring, of which, in ‘ Zamia', there are only very 
inconspicuous traces. It should be stated, however, that 
the plants called by him Zamia , are now placed by modern 
botanists under the genus Encephalartos 2 . 
In the monograph by Miquel 3 some of the anatomical 
characteristics of several genera are briefly touched upon, 
mention being made of such points as the nature of the pith, 
the pittings on the tracheides of the wood, &c. 
In the work on the Cycads by Mettenius 4 * , which may 
perhaps be considered the best hitherto published, a great 
deal more light is thrown on the whole structure, and we are 
enabled to see very much more clearly how matters really 
stand with regard to the anatomy of these plants. It is from 
this paper that we have obtained most of our knowledge about 
Cycadean stems. He treats of the structure of Cycas revoluta , 
1 Abh. der k. b. Acad, zu Miinchen, I, 1832 ; republished and revised in 
Vermischte Schriften, 1845. 
2 See v. Mohl, loc. cit., Verm. Schriften, p. 198, foot-note. His ‘ Zamia latifolia ’ 
was an African Encefihalartos , and had nothing to do with the true Z. latifolia , 
Loddiges. 
3 Monographia Cycadearum, 1842. 
4 Beitrage zur Anatomie der Cycadeen, Abh. der K. Sachs. Gesellsch. der Wiss., 
VII, 1861. 
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