37. Q. What are the simplest forms of plant life? A. Those that consist
of a single cell.
38. Q. In the higher classes of plants what is the character of the union
of cells which forms tissues and organs? A. It is permanent.
39. Q. What are made by the union of cells into groups? A. The woody
fibers of plants, and the cellular tissue which makes the softer, fleshy
and pithy parts.
40. Q. What has observation shown as to the production of new cells in
the highest plants? A. That they are not produced everywhere uniformly,
but in particular spots.
41. Q. What terms have been applied to places of this kind? A.
Growing-point, and growing or formative layer.
42. Q. Where may growing-points and formative layers be seen? A.
Growing-points may be seen in the tips of buds, and formative layers
between the wood and bark of trees.
43. Q. What names have been given to the tissue which is here formed by
the division and union of cells? A. Formative or generating tissue.
44. Q. What are in direct contrast to the generation tissues? A. The
healing tissues, or cork tissues.
45. Q. How are vessels made? A. By the union of several cells, the
partition-walls disappearing, while the union continues at the margin.
46. Q. What are bast-tubes or bast-fibers? A. They are long, pointed,
thick-walled tubes, commonly united into bundles.
47. Q. To what part of the flower is the term nectaries, or honey-glands,
given? A. To any part of a flower which secretes honey or sugary fluids.
48. Q. What is the first independent tissue formed in flowering plants by
the union of cells? A. The epidermis or skin.
49. Q. What is each of the pores found among the epidermic cells called?
A. A stoma, or mouth.
50. Q. What are hairs? A. They are epidermal structures, composed of one
or more cells.
51. Q. What do we find next to the epidermis? A. The cortex, or bark,
often composed of cells containing starch or chlorophyll.
52. Q. What is beneath the bark? A. The formative layer or cambium, in
which thin-walled cells become transformed into vascular or bast-cells,
and thence are changed into permanent cells.
53. Q. What do groups of cells thus formed, united into bundles and
penetrating the rest of the tissue, form? A. The fibro-vascular bundles.
54. Q. What are the simpler types of plants that have no fibro-vascular
bundles, called? A. Cellular plants.