40G 
PEOFESSOE W. C. WILLIAMSON ON THE ORGANIZATION 
value. To all these friends I can only return my cordial thanks for the aid they have 
so kindly rendered. 
Description of the Plates. 
Lygino dendron Oldhamium. 
Plate XXII. fig. 1. Transverse section of a young stem with an exogenous branch 
emerging through the bark, magnified 4f diameters. 
„ fig. 2. Medullary axis and inner part of the ligneous zone of a very 
young stem, magnified 40 diameters. 
,, fig. 3. Segment of a ligneous zone with one of the detached vascular 
masses of the medullary axis, magnified 50 diameters. 
„ fig. 4. Transverse section of the entire vascular axis of a young stem, 
with an external young and half-developed vascular layer ; mag- 
nified 6 diameters. 
,, fig. 4'h Reticulated vessel of the ligneous zone, magnified 200 diameters. 
,, fig. 5. Transverse section of the cellular tissue of the medulla, magnified 
150 diameters. 
Plate XXIII. fig. G. Segment of a transverse section of a young stem with a young 
exogenous layer of half-developed vessels, magnified 50 diameters. 
„ fig. 7. Segment of a transverse section of a young stem, giving off a 
supposed root-bundle, magnified 50 diameters. 
„ fig. 8. Tangential section of the ligneous zone, composed of a network of 
vessels and numerous medullary rays, magnified 70 diameters. 
„ fig. 9. Radial section of part of a ligneous zone, with portions of two vas- 
cular lamina; (e), and one medullary ray composed of mural cells 
(/'), magnified 70 diameters. 
Plate XXIV. fig. 10. Transverse section of part of the bark, with its several divisions 
of innermost layer (g), parenchymatous layer (h), prosenchymatous 
layer (Jc), and subepidermal layer (l), magnified 50 diameters. 
„ fig. 11. Tangential section of the ligneous zone, giving off a lateral branch : 
the section intersects the bark (</, h, and Jc) almost radially ; It', fre- 
quent patches of dark-coloured cells : magnified 6 diameters. 
„ fig. 12. Portion of fig. 11, magnified 18 diameters. 
,, fig. 13. Tangential section of the prosenchymatous layer of the bark, with 
its prosenchymatous bands and cellular areolae, magnified 5 
diameters. 
Plate XXV. fig. 14. Tangential section of the prosenchymatous layer of the bark of 
a young stem, with a branch emerging through it, magnified G 
diameters. 
Plate XXIY. fig. 15. Tangential section of the prosenchymatous layer of the bark, 
