First, the whales forming the margin of our lake began to crowd a little, and tumble against each other, as if lifted by half spent billows from afar; then the lake itself began faintly to heave and swell; the submarine bridal-chambers and nurseries vanished; in more and more contracting orbits the whales in the more central circles began to swim in thickening clusters.
Aphidesand may be easily penetrated by certain Fungi such as Peziza, Nectria; and when thus attacked, the repeated conflicts between the cambium and callus, on the one hand, trying to heal over the wound, and the insect or Fungus, on the other, destroying the new tissues as they are formed, results in irregular growths; the still uninjured cambium area goes on thickening the branch, the dead parts, of course, remain unthickened, and the portion in which the Fungus is at work may for the time being grow more rapidly.
D, stages in the development of the broodcapsules in Echinococcus: a, the thickening of the parenchyma of the bladder; b, subsequent formation of a cavity in it; c, development of the suckers; d, a capsule with one head inverted into its cavity; e, a capsule with two heads; X 90.
Have a spiral, annular, or reticulated thickening of the wall.
It is a noteworthy fact that other tubes in these same terrestrial Arthropoda - namely, the ducts of glands - are similarly strengthened by a chitinous cuticle, and that a spiral or annular thickening of the cuticle is developed in them also.
The thickening of the epidermis in the hands and feet, which occurs from constant use, is nature's provision for meeting the extra wear to which these parts are subjected by much use; but pressure is apt to cause the defensive process to be carried too far, and to lead to corns, which give rise to much pain and annoyance.
We may note that it was long since shown that the apical organ (at first assumed to be the brain) of these larvae was innervated from an anterior thickening of the circular nerve ring, corresponding with the brain of Rotifers; the nerve cells immediately below the pit are the ordinary bipolar From H.
The artist can accentuate the high lights or solids in the original drawing or photograph, and the stereotyper can emphasize points in the picture by thickening the plate in the parts necessary to stand out.
The clitellum consists of a thickening of the epidermis, and is of two forms among the Oligochaeta.
There is no secondary thickening except at the node in E.