JOURNAL 



OF THE 



ROYAL MICROSCOPICAL SOCIETY. 



DECEMBEK, 1879. 



TRANSACTIONS OF THE SOCIETY. 



XXXV. — O71 the Morpliology of Vegetable Tissues. 

 By W. H. GiLBURT, F.E.M.S. 



(Head 8th October, 1879.) 

 (Plates XXII. and XXIII.) 



In the early autumn of last year, while examining some pre- 

 parations I had been making of the leaf-buds of various trees, 

 certain appearances were observed, which seemed scarcely to agree 

 with the views now held, concerning the origin of the cambium 

 layer in the stems of the woody dicotyledons ; and suggested the 

 desirability of a further study of the subject. 



During the twelvemonth which has since elapsed I have 

 followed up the inquiry, with results of at least considerable 

 interest, 



EXPLANATION OF PLATES XXII. AND XXIII. 



All figures drawn icith Camera Lucida. 



pc6, procambium ; c6, cambium; ?wr, medullary rays; m, medulla; c, cortex; 

 sv, spiral vessel ; ss, sieve septa ; ry, rudimentary vessels. 



Figs. 1, 2.— Sections through procambium of Ci/tisus laburnum, showing earliest 

 observed appearance of cambium. Fig. 1. Very oblique, radial diameter of cells 

 much exaggerated. 



Figs. 3-5. — Sections through procambium of Lombardy poplar. Fig. 3. Show- 

 ing first division of procambium cells. Figs. 4, 5. Two stages in development 

 of cambium. 



Figs. 6-8. — Sections of Ficus carica. Fig. 6. Before division of generating 

 cells (m xylem side. Fig. 7. Enlargement, division, and thickening of cells, pro- 

 ducing first vessels of medullary sheath. Fig 8. Appearance of cambium septa 

 in cells dividing thickened cell-forms. 



Figs. 9-11. — Tangential sections through cambium of Cytisus laburnum. 



Figs. 12, 13. — „ „ Syringa vulgaris. (Figs. 



9, 10, 12, 13. Showing cambium cell-groups. Fig. 11. Same after absorption of 

 transverse septa. Medullary rays in transverse section.) 



Fig. 14. — Section through cambium of Salisburia adiantifolia. 



Fig. 15. — Development ot vessels in Sambucus nigra; sieve septa indicated by 

 dotted lines ; transverse septa still remaining. 



Fig. 16. — Sieve septa in rudimentary vessels of Ailanthus glandulosus ; very 

 oblique, and cut through. 



VOL. II. 3 H 



