54 SELECTED NOTES FROM THE SOCIETY'S NOTE-BOOKS. 



portion of the stem is the zone of growth — cambium — indi- 

 cated by cb. ; v.b., v.b., vascular bundles, porous and annular 

 vessels embedded in a mass of wood-cells ; c.t., cellular tissue. 



Fig. 2. — Portion of a longitudinal section ; c.t., cellular tissue, the 

 elements of which are seen to be porous ; 2>-^-; porous vessels, 

 not very distinctly seen, owing to surrounding wood-cells. 



,, 3. — Si^iral vessels and raphides from stem of rhubarb, x 100. 



Plate V. 



Transverse section of stem of Periploca Grceca, x 50, showing to a 

 certain extent the structure of the pith, ^5. ; wood, w. ; and bark, b. 



The wood is seen to be lax, with very numerous large ducts, d.d. ; 

 from minute fragments to be seen here and there, these are evidently 

 porous ducts, cb. indicates the cambium layer, or common centre of 

 growth for wood and bark, equivalent to the basement membrane in 

 animal tissues; /i./i., bases of hairs arising from the ectoderm ; m,.r., 

 m.r., medullary rays, very numerous and fine, whose purpose is to 

 keep up the vital connection between the central structures and the 

 seat of vital growth. These are seen to be continued, though in an 

 imperfect form, into the bark. The black patches, present through- 

 out, but most strikingly so in the bark, are of an inspissated resinoid 

 juice, and constitute the feature of sj^ecial interest in the specimen. 



Plate VI. 



Fig. 1. — Flower of Deutzia (jraciUs, natural size, to show the position 

 whence the figures have been taken. 



,, 2. — Portion of the ovary, with stellate hairs, x 50. 



,, 3. — Portion of the petal on which these hairs are also sparingly 

 present, x 50. 



,, 4, 5. — Pollen of Oxalis acetosella, end and side views. 



,, G. — Empty egg-shell of Bot-fly, seen in profile. 



,, 7. — One of the lids. 



,, 8. — Outline of another lid, curled during the process of prepara- 

 tion for mounting. 



,, 9. — Part of one of the shells more enlarged, to show that the 

 apparent hole is but a deep depression. The scale-like reti- 

 culation near the upper edge of a specimen is also shown, as 

 well as the way in which this passes gradually into undulated 

 transverse lines. 



,, 10. — Front view of the upper part of the opening, to show the 



deep hollow, now looking much like a hole. 

 ,, 11.— Edge of a part of a specimen, to show the wavy transverse 



lines to be really projecting ridges. 



,, 12. — Transverse section of egg-shell of Acrida viridlssima, drawn 

 by A. Hammond. 



,, 13. — Stomach of Bee, showing the beautifully arborescent charac- 

 ter of tracheae supplied to that part of this insect. 



Plates IV., v., and VI. drawn by Tuifen West except Fig. 12, 

 Plate VI. 



