376 INCREASE OF CYCADE^ BY BUDS. 



megalophyllus, and Cycadites microphyllus (see PI. 60, Fig. 

 1, and PI. 61, Fig. 1,) and form an important point of agree- 

 ment in the Physiology of the Uving and fossil Cycadese* 



Thus, we see that our fossil Cycadites are closely allied 

 by many remarkable characters of structure, to existing 

 Cycadese. 



l.By the internal structure of the trunk, containing a ra- 

 diating circle, or circles, of woody fibre, embedded in cellu- 

 lar tissue. 2. By the structure of their outer case, composed 

 of persistent bases of petioles, in place of a bark ; and by all 

 tlie minute details in the internal organization of each Pe- 

 tiole. 3. By their mode of increase by Buds protruded 

 from ixerms in the Axillee of the Petioles. 



* In the fossil trunk of Cycadites microphyllus, PI. Gl. Fig. 1, we see 

 fourteen Buds protruding from, the axillEe of the leaf stalks, and in PI. 60, 

 Fig. 1, we have three Buds in a similar position in Cycadites megalophyllus. 



In PI. 61, Figs. 2, 3, exhibit transverse sections of three Buds of Cyca- 

 dites niycrophyllus. The section of the uppermost bud. Fig. 3, g, passes 

 only through the leaf stalks near its crown. The section of the bud, Fig. 

 3, 'd, being lower down in the embryo trunk, exhibits a double woody cir- 

 cle, arranged in radiating plates, resembling the double woody circle in the 

 mature trunk, PI. 61, 1, B,b. But in PI. 61, Fig. 2, the laminated circle within 

 the embryo trunk near d, is less distinctly double, as might be expected in so 

 young a state. 



At PI. 62, Fig. 3, d, and d', we see magnified representations of a portion 

 of the embryo circle within the Bud, Pi. 61. Fig. 3, 'd. These woody cir- 

 cles within the buds, are placed between an exterior circle of cellular tissue' 

 interspersed with gum vessels, and a central mass of the same tissue, as in 

 the mature stems. 



On the right of the lower bud, PI. 61, Fig. 3, above b, and in the magni- 

 iied representations of the same at PI. 62, Fig. 3, e, we have portions of a 

 small imperfect laminated circle. Similar imperfect circles occur also near 

 the margin of tlie sections, PI. 61, Figs. 2. 3, at e, c', e" ; these may be im- 

 perfectly developed Buds, crowded like the small Buds near the base of the 

 living Cycasj PI. 58: or they may have resulted from the confluence of the 

 bundles of vessels, in the Bases of leaves, forced together by pressure, con- 

 nected with a diminution or decay of their cellular substance. The normal 

 position of these bundles of vessels is seen magnified in PI. 62. Fig. 3. c. and 

 in nearly all the Sections of Bases of petioles in PI. 61. Fig. 2, 



