240 Bailey. — The Relation of the Leaf -trace to the Formation of 
many species of woody plants, and to Mr. A. J. Eames for Figs. 12 and 15, 
and for the opportunity of examining serial sections of herbaceous and 
semi- herbaceous plants. 
DESCRIPTION OF PLATES XV-XVII. 
Illustrating Mr. Bailey’s paper on Compound Rays in Lower Dicotyledons. 
(It is suggested that a hand lens be used in the examination of the figures.) 
PLATE XV. 
Fig. 1. Alnus actiminata. Tangential section of the mature wood, showing non-aggregated 
uniseriate rays. x 40. 
Fig. 2. The same. Transverse section, x 40. 
Fig. 3. Alnus incana. Tangential section of the mature wood, showing in the central portion 
a band of aggregating uniseriate rays, x 40. 
Fig. 4. The same. Transverse section, x 40. 
Fig. 5. Alnus rubra. Tangential section of the mature wood, showing a higher step of the 
aggregating process in which the rays have increased in size to bi- and tri -seriate and are coalescing 
in places, x 40. 
Fig. 6. The same. Transverse section, x 40. 
Fig. 7. Alnus maritima. Tangential section of the mature wood, showing an advanced stage 
of the compounding process in which the coalescing mass has taken on the fusiform outline of 
a large oak ray, and in which the fibres included in the tissue are being transformed into parenchyma, 
x 40. 
Fig. 8. The same. Transverse section. x 40. 
Fig. 9. Alnus rhombifolia. Tangential section of the mature wood, showing a completely 
fused aggregate or compound ray which is composed of a homogeneous mass of parenchymatous 
tissue homologous to the large oak ray seen in Fig. 1 1. x 40. 
Fig. 10. The same. Transverse section of the wood, showing an intermediate step between 
those shown in Figs. 7 and 9. x 40. 
Fig. 11. Quercus rubra . Tangential section of the wood, showing the large aggregate ray 
which is characteristic of American oaks with deciduous foliage, x 40. 
Fig. 12. Quercus virginiana. Tangential section of the wood, showing a compounding 
condition similar to that seen in Alnus rzibra in Fig. 5. x 40. 
PLATE XVI. 
Fig. 13. Quercus virginiana. Transverse section of the wood, showing aggregating tissue in 
which fibres and wood parenchyma cells are being transformed into ray parenchyma, x 40. 
Fig. 14. Quercus alba. Tangential section of traumatic wood, showing the reversion of 
wounded wood to primitive stages of compounding in the large rays, x 80. 
Fig- 15. Quercus velutina. Tangential section of the seedling plant, showing primitive 
compounding phase similar to that which occurs in the mature wood of Alnus rubra and Quercus 
virginiana. x 40. 
Fig. 16. Lyginodendron oldhamium. Transverse section of the primary and secondary wood, 
illustrating the fact that the wood rays originate with secondary growth and do not extend into the 
metaxylem or have any relation to the fundamental tissue or medulla, x 20. 
Fig. 17. Alnus tenuifolia. Transverse section of a small twig, showing a primitive condition 
of the woody cylinder, which is seen to consist of a solid homogeneous tubular cylinder except at the 
points where the lateral leaf-traces (marked x) and associated tissue are interposed. x 15. 
