The wood is compact and fine grained, the rings of secondary tissue being developed from a normal cambium as in the case of the higher Gymnosperms, and the individual tracheae have round bordered pits.
Tracheae of Wood of Botryopteridean Fern in Longitudinal Section, showing the rows of pits on the walls.
Tracheae are abundant just in proportion as blood-vessels become suppressed.
In Peripatus the stigmatic pits at which the tracheae communicate with the atmosphere are scattered and not definite in their position.
A great point of interest therefore exists in the knowledge of the structure and embryology of tracheae in the different groups.
Tracheae are developed which are dendriform and with spiral thickening of their lining.
Having accepted these two conclusions, we formulate the generalization that tracheae can be independently acquired by various branches of Arthropod descent in adaptation to a terrestrial as opposed to an aquatic mode of life.
Usually the tracheae open by paired stigmata placed upon the sides of a greater or less number of the somites, but never quite regularly on alternating somites.
When the facile tendency of Arthropoda to develop tracheal air-tubes is admitted, it becomes probable that the tracheae of Hexapods do not all belong to one original system, but may be accounted for by new developments within the group.
The tracheae have made their appearance, and the mouth is provided with a pair of mandibles.
Richard erroneously supposes that Grew did not know of the tracheae till 1682.
Sometimes they are tracheae or air-vessels, which, as in the class Insecta, replace those of circulation.
He further affirms, that they are only the large trunks of the Tracheae that cast their skins, none being detached from their smaller ramifications[481].
The Trachean Arachnida have only a pair of spiracles, from which the tracheae must radiate, if I may so apply the term, in order to convey the necessary supply of air to every part of the body.
The tracheae to the central nervous system in many instances enter the nervous system bound up in the same sheath as the nerves.
In front of the mouth there is a very large median ventral tracheal pit, which gives off tracheae to the ventral part of the nervous system, and still more in front a large number of such pits close together.
At this nick it is firmly attached to the ventral side of the foot by muscles and tracheae, and when cut away from its attachment the muscles and tracheae cannot easily be detached from it.
The tracheae themselves are extremely minute, unbranched (so far as I could follow them) tubes.
Cuvier says that the internal membrane of the tracheae being soft and moist, appears calculated to receive scents[1064].
Part of one of the tracheae of ditto, to show its coats and spiral thread.
Tracheae send off at equal distances lateral branches just as if there were spiracula to correspond with them.
The air-tubes of the Woodlice, however, are precisely like tracheae in structure and function, and only differ from the tracheae of the other groups in the fact that they are confined to the appendages, and do not penetrate into the body.
The specimens shewing tracheae which Moseley has placed in my hands are quite sufficient to leave no doubt whatever in my mind as to the general accuracy of his description of the tracheal system.
The anterior atrophies, and the posterior acquires tracheae and gives rise to the first pair of wings.
The development of the tracheae strongly supports the view, arrived at by Moseley from his investigations on Peripatus, that they are modifications of cutaneous glands.
When the insect contracts its body, the tracheae are compressed and the air driven out.
The number of tracheae in the body of an insect is very great.
The air penetrates into the tracheae by a number of orifices placed at the sides of the body, which are termed spiracles.
In Scutigera the tracheae differ both in structure and position from those of all other Chilopoda.
B, Two segments of Scolopendra, showing the branching and anastomosing tracheae and a spiracle (sp).
The apertures, as in the case of other genera, are protected by fine hairs; and the tracheae themselves are strengthened by a fine spiral filament.
Probably tracheaehave developed independently by the same process in several groups of tracheate Arachnids.
A supplementary pair of tracheae opening behind the basal segment of the 4th appendage of the prosoma.
The appearance oftracheae in place of lung-sacs cannot be regarded as a starting-point for a new line of descent comprising all the tracheate forms; tracheae seem to have developed independently in different lines of descent.
Tracheae opening by a pair of stigmata situated above and behind the base of the 4th or 5th or 6th pair of appendages.
Tracheae typically opening by stigmata situated in the articular sockets (acetabula) of the 3rd, 4th, 5th and 6th pairs of appendages.
The tracheae are formed in the most wonderful manner, so as to keep them always open, that the air can readily pass through them.
As these animals have no circulating fluid except the air in their tracheae and bronchiae, their locomotive powers, with few exceptions, must depend altogether upon the state of that element.
The vessels contained in the nervures consist of a spiral thread, whence they appear to be air-vessels communicating with the tracheae in the trunk.
In their internal anatomy the arachnids show in some forms a peculiar modification of the respiratory organs, the tracheae being flat and leaf-like and massed together in a few groups rather than being tubular and ramifying through the body.
The insects, in further contradistinction to the crustaceans, are mostly land animals and breathe by means oftracheae or tracheal gills.
The Myriapoda are land-animals breathing by means of tracheae like the insects.
Respiration is carried on by gills in the aquatic forms, and by a remarkable system of air-tubes or tracheae in the land forms (insects).
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "tracheae" in a variety of sentences. We hope that you will now be able to make sentences using this word.
