Hardwicke's science-gossip : an illustrated medium of interchange and gossip for students and lovers of nature . e tracheal wall, and the inner layers ofnearly the whole alimentary canal are continuousand equivalent structures. The lining of the largertracheal tubes at least is shed at every moult, likethat of the stomodreum and proctodaeum. branched. It is interrupted frequently, each lengthmaking but a few turns round the tube, and endingin a point. The thread of a branch is never cnntinuedinto a main trunk. Both the thread and theintervening membrane become invisible or faint whenthe tissue
Hardwicke's science-gossip : an illustrated medium of interchange and gossip for students and lovers of nature . e tracheal wall, and the inner layers ofnearly the whole alimentary canal are continuousand equivalent structures. The lining of the largertracheal tubes at least is shed at every moult, likethat of the stomodreum and proctodaeum. branched. It is interrupted frequently, each lengthmaking but a few turns round the tube, and endingin a point. The thread of a branch is never cnntinuedinto a main trunk. Both the thread and theintervening membrane become invisible or faint whenthe tissue is soaked with a transparent fluid, so as toexpel the air. Both, but especially the thread. HARDWICKES SCIENCE-GOSSIP. 205 absorb colouring matter with difficulty. The thread, •from its greater thickness, offers a longer resistanceto solvents, such as caustic alkalies, and also tomechanical force. It can therefore be readily divided into polygonal areas, each of which isoccupied by a reticulation of very fine threads. Thisstructure may be traced for a short distance betweenthe turns of the spiral
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