Guide to the study of insects and a treatise on those injurious and beneficial to crops, for the use of colleges, farm-schools, and agriculturists . twofilaments with the ventral gan-glionic mass, formed by theprobable union of several gan-^^ glia, and situatedin the middleFig. 622. of the false cephalothorax. The continuation of the nervous cord consists of seven abdominalganglia, with the commissures united into a single cord. The maxillary palpi, functionally, take the place of antennae,showing how one organ may perform the office of another in adifferent group of animals. It is also eviden
Guide to the study of insects and a treatise on those injurious and beneficial to crops, for the use of colleges, farm-schools, and agriculturists . twofilaments with the ventral gan-glionic mass, formed by theprobable union of several gan-^^ glia, and situatedin the middleFig. 622. of the false cephalothorax. The continuation of the nervous cord consists of seven abdominalganglia, with the commissures united into a single cord. The maxillary palpi, functionally, take the place of antennae,showing how one organ may perform the office of another in adifferent group of animals. It is also evident that the spidercombines in the same organ the senses of taste, smell and feel-ing, which are supposed in insects to reside in the two pairs ofpalpi and the antenna?. Mygale and Scorpio stridulate. The alimentary canal is formed, according to Siebold, on twotypes. In the mites and spiders, the stomach is produced latr. ARACHNIDA. 629 erally into large ca3cal appendages (Fig. 022, alimentary canalof Tegenaria civilis ; a, stomach, witli coeca ; c, liver ; cl, renalorgan; e, fat bod^), and then passes into a short, small intes-tine, going straight to the end of the bod^. In the Pedipalpes(Phrynidifi and Scorpions) the intestinal canal is more simple,not having any coecal dilatations to the very small stomach. The salivary glands are often of large size, especially inIxodes, and are thns adapted to Ihcir blood-sucking habits,much saliva being needed to mix with their food. In thespiders and scorpions the liver is well developed and distinctfrom the intestinal tube, being in tli& spiders a brown or dirty3ellow mass filling a large part of the abdominal cavity andenveloping most of the other viscera. As during the growth of the young spider the head is thrownback on top of the thorax to which it is thus most closelj^ uni-ted, it follows that the simple ej-es, from two to twelve innumber, are situated
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Keywords: ., bookcentury1800, bookdecade1880, bookpublishe, booksubjectinsects
