She joined the Germans and other backpackers in an Irish dance as the cigarette smoke thickened and the rock band grew louder.
The medusae of this order are characterized by the tough, rigid consistence of the umbrella, due partly to the dense nature of the mesogloea, partly to the presence of a marginal rim of chondral tissue, consisting of thickened ectoderm containing great numbers of nematocysts, and forming, as it were, a cushion-tyre supporting the edge of the umbrella.
The umbrella is shallow and has the margin supported by a rim of thickened ectoderm, as in the Trachomedusae, but not so strongly developed.
As a result of this extension of the umbrellar margin, all structures belonging to this region, namely, the ring-canal, the nerve-rings, and the rim of thickened ectoderm, do not run an even course, but are thrown into festoons, caught up under the insertion of each tentacle in such a way that the ring-canal and its accompaniments form in each notch of the umbrellar margin an inverted V, the apex of which corresponds to the insertion of the tentacle; in some cases the limbs of the V may run for some distance parallel to one another, and may be fused into one, giving a figure better compared to an inverted Y.
In relation to its characteristic function of protection, the epidermis, which, as above defined, consists of a single layer of cells has typically thickened and cuticularized outer walls.
Isolated celh (idioblasts), thickened in various ways, are not uncommonly founc supporting the tissues of the leaf.
This consists of elongated cells with cellulose walls, which are locall~ thickened along the original corners of the cells, reducing the lumer to a cylinder, so that a number of vertical pillars of cellulose con nected by comparatively thin walls form the framework of th~ tissue.
During the process the thin walls are stretched and the turns of the spiral become pulled apart without rupturing the wall of the tracheid or vessel, If the pitted type of tracheal element were similarly stretched its continuously thickened walls would resist the stretching and eventually break.
Thus the structure of an old thickened root approximates to that of an old thickened stem, and so far as the vascular tissue is concerned can often only be distinguished from the latter by the position and orientation of the primary xylems. The cambium of the primary root, together with the tissues which it forms, is always directly continuous with that of the primary stem, just in the same way as the tissues of the primary stele.
It is thickened more in some places than in others, and thus are formed the spiral, annular and other markings, as well as the pits which occur on various cells and vessels.
Besides the internal or centripetal growth, some cell-walls are thickened on the outside, such as pollen grains, oospores of Fungi, cells of Peridineae, &c. This centrifugal growth must apparently take place by the activity of protoplasm external to the cell.
The beetles have feelers with eleven segments, whereof the terminal few are thickened so as to form a club.
This may be associated with mud-eating habits; but it is not wholly certain that this is the case; for in Chaetogaster and Agriodrilus, which are predaceous worms, there is no protrusible pharynx, though in the latter the oesophagus is thickened through its extent with muscular fibres.
When the races were over, and we turned our faces homeward, one of the party noticed a black cloud drifting in from the sea, which grew and spread and thickened until it covered the whole sky.
The verdure had thickened and its bright green stood out sharply against the brownish strips of winter rye trodden down by the cattle, and against the pale-yellow stubble of the spring buckwheat.