PLATE V. 
Fig. 
29. — Young leaf of wheat ; it is seen to possess the free capsule of cells and 
epidermic plasm, closely identical with those of the root. 
29*. — Portion of edge of the above much magnified, 
30. — Some of the free cells from the above, detached. 
31. — Transverse section of embryo leaf folded, with its straw-coloured 
envelope. 
32. — Double ovate granules and molecules, showing a tendency to regular 
arrangement ; from formative matter at an early age. 
33. — Appearance of nuclei with nucleoli and vesicles, in formative matter at 
a stage more advanced than the last. 
34. — Cells increasing by sub-division ; from maize-leaf. 
35. — Annular, spiral, scalariform, and pitted vessel, in juxtaposition; 
maize. 
36. — Early formation of pitted vessel ; maize. 
37. — Dark spots indicating the commencement of actual perforation of the 
delicate membrane at the base of the pits in a " pitted " vessel ; 
maize. 
38. — Progress of absorption of basement membrane, spirally ; maize. 
39. — Transverse section, root of maize, showing the pentangular form 
assumed by scalariform tissue, through pressure of the surrounding 
cell-structure. 
40. — Scalariform vessel from young cucumber, unrolling; its pentangular 
form is thus very distinctly brought out. 
41. — Absorption of basement membrane in a linear direction, in the pro- 
duction of an annular vessel. 
42. — Transverse section of a pitted vessel, a portion of the cut edge projects 
and shows well the production of the " pits," also lines indicating the 
layers of secondary deposit on the cell-wall. 
43. — Rudimentary spiral fibre ; plumule of wheat. 
44. 45. — Early stage in formation of scalariform tissue; young vegetable 
marrow. 
46. — The same, showing formation of a scalariform vessel, by the addition 
of cell to cell, and absorption of their walls at the points of con- 
tact. 
