The house-fly, Musca domestica Linn: its structure, habits, development, relation to disease and control . channels are kept openby means of small incomplete chitinous rings which give thepseudo-tracheae their annular ajDpearance. Each of these incom-plete chitiiious rings is bifurcated at one end but single at theother end (fig. 4). The rings are so arranged that the bifidends alternate with the single ends. The pseudo-tracheal channelcommunicates with the external surface of the oral lobes throughthe opening through the bifid extremities of each ring, as isshown in the accompanying figure (f
The house-fly, Musca domestica Linn: its structure, habits, development, relation to disease and control . channels are kept openby means of small incomplete chitinous rings which give thepseudo-tracheae their annular ajDpearance. Each of these incom-plete chitiiious rings is bifurcated at one end but single at theother end (fig. 4). The rings are so arranged that the bifidends alternate with the single ends. The pseudo-tracheal channelcommunicates with the external surface of the oral lobes throughthe opening through the bifid extremities of each ring, as isshown in the accompanying figure (fig. 5). From the outeredge of the oral lobe the pseudo-tracheae gradually increase in sizeas they approach the inner margin of the lobe. The number 16 THE EXTERNAL STRUCTURE OF jMUSCA DOMESTICA of pseudo-tracheae traversing each oral lobe is thirty-six, andthey are giouped in three sets. One anterior set of twelvepseudo-tracheae run into a single large pseudo-tracheal channelrunning along the anterior inner margin of the oral lobe, anda posterior set of twenty or twenty-one all run into a common t S--.
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Keywords: ., bookcentury1900, bookdecade1910, bookpublishercambridgeuniversit
