. The physiology of the Invertebrata. nsectby the action of the maxillary plates were filtered, as itwere, into the narrow oesophagus. In Mygale, however,there is only one aper-ture. The oesophagusleads into a stomach pro-duced into several lateralappendages, which some-times extend into thelimbs. The stomach ofTegenaria domestica, andother species, is capableof great distension, andpasses directly into theintestine, which dilatesinto a rectum and thenjberminates in an the intestine openseveral so-called biliaryducts, The latter arethrown off from a largeorgan (Fig. lo) situatedon ei
. The physiology of the Invertebrata. nsectby the action of the maxillary plates were filtered, as itwere, into the narrow oesophagus. In Mygale, however,there is only one aper-ture. The oesophagusleads into a stomach pro-duced into several lateralappendages, which some-times extend into thelimbs. The stomach ofTegenaria domestica, andother species, is capableof great distension, andpasses directly into theintestine, which dilatesinto a rectum and thenjberminates in an the intestine openseveral so-called biliaryducts, The latter arethrown off from a largeorgan (Fig. lo) situatedon either side of the in-testine, but which isgreatly concealed by largemasses of adipose tissueoccupying the sides ofthe abdomen. This organhas not the function of aliver, for its secretion isof a pancreatic nature. In front of the rectum open two long slender tubes whichoften branch; these are the Malpighian tubules. Salivaryglands are also present. Spiders are carnivorous animals,and the females are sometimes addicted to cannibalism. D. Fig. io.—Diagram of the AlimentaryCanal of Pholcus rivulatus. a = salivary glands. b = stomach. c = intestine. (^ = so-called liver. e = Malpighian tubules. /= rectum. so PHYSIOLOGY OF THE INVERTEBRATA. They devour their Eomeos, if the latter are in the leastobnoxious. (i8) The Arthrogastra.—In this order, to which thescorpion belongs, the mouth is situated between the labrumin front, the bases of the pedipalpi and those of the firsttwo pairs of ambulatory limbs at the sides and behind. Itis a very small aperture and leads into a pharyngeal sacwith chitinous walls. The pharynx passes into a narrow(Esophagus, and into this two ducts from large salivaryglands discharge the secretion. The intestine forms prac-tically a straight tube which terminates in an anus. As inthe Araneina, numerous so-called biliary ducts open intothe intestine. The pancreas or digestive gland (the so-calledliver) is extremely well developed in Scorpio, occupying allthe sp
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectinverte, bookyear1892
