Hardwicke's science-gossip : an illustrated medium of interchange and gossip for students and lovers of nature . he rectal bands are well developeddo not take water into the intestine at all. Gegen-baur has therefore modified Leydigs *suggests, (Grundzuge d. Vergl. Anat.) that thefunctional rectal folds of dragon-flies and the non-functional folds of terrestrial insects are both survivalsof tracheal gills, which were the only primitiveorgans of respiration of insects. The late appearanceof the rectal folds and the much earlier appearance related to the six theoretical elements (tw
Hardwicke's science-gossip : an illustrated medium of interchange and gossip for students and lovers of nature . he rectal bands are well developeddo not take water into the intestine at all. Gegen-baur has therefore modified Leydigs *suggests, (Grundzuge d. Vergl. Anat.) that thefunctional rectal folds of dragon-flies and the non-functional folds of terrestrial insects are both survivalsof tracheal gills, which were the only primitiveorgans of respiration of insects. The late appearanceof the rectal folds and the much earlier appearance related to the six theoretical elements (two tergal,two pleural, two sternal), traceable in the arthropodexoskeleton, of which the proctodeum and stomo-daeum are reflected folds. The anus of the cockroach opens beneath the tenthtergum, and between two podical plates. Analglands, such as occur in some beetles, have not beendiscovered in cockroaches. The three principal appendages of the alimentarycanal of the cockroach are outgrowths of the threeprimary divisions of the digestive tube ; the salivaryglands are diverticula of the stomodseum, the ca^cal.
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Keywords: ., bookcentury1800, booksubjectnaturalhistory, booksubjectscience
