366 PHYSIOLOGY. 



fluid portion of the chyme. But if the period of fasting he too much 

 prolonged the caterpillar dies, and the food is even then found in 

 the stomach. In general voracious caterpillars, which usually consume 

 daily three times their own weight of food, cannot fast very long, at 

 least not more than eight or ten days ; perfect insects, namely, some 

 beetles, can do without food much longer. I myself have seen a Blaps 

 mortisaga move about quite briskly after having fasted for three entire 

 months. Other instances have been observed in capricorn beetles 

 which have been enclosed in wood for years ; they were in a torpid 

 state, but revived upon being exposed a short time to the air. Pre- 

 daceous beetles, such as the large Carabi and Dytici, cannot long fast, 

 at most a few weeks. Caterpillars which are not fed after their last 

 moult do not die, but change into pupae, but the pupae are easily killed, 

 particularly if the caterpillar immediately after moulting has been 

 deprived of food ; but the voracity of caterpillars decreases with the 

 increase of their age, and it is only during the first period of their 

 existence that they exhibit a hunger which is almost without parallel. 

 Many beetles, viz., the Carabi, the grasshoppers, and the larvae of 

 the Lepidoptera, eject upon being touched a brown, corrosive, gastric 

 juice, and cast it at their enemies. Whoever has collected insects, and 

 especially the Carabodea, nuist be well acquainted with this mode of 

 their defence, as also with the pain which the intrusion of it occasions 

 when by accident, which is not rarely, it comes into the eye. This 

 acute pain, which occasions a gush of tears, distinctly proves the 

 sharp and caustic quality of the gastric juice. In some Hymenoptera, 

 namely, in the bees and wasps *, the ejection of the food regularly 

 takes place, for they cast up, farther elaborated, the imbibed nectar of 

 flowers, and supply the young with it as food. The ejection of it is 

 caused by the antiperistaltic motion of the stomach and proventriculus, 

 and thus the gastric juice is passed into the mouth by a contorted 

 motion of the animal, whence by another quick bending it is thrown 

 from it. According to Rengger the muscles of the skin also contribute 

 considerably to the retrograde motion of the stomach, at least the force 

 was considerably diminished when he cut the caterpillar along the back, 

 and then irritated it by pressing and tormenting, causing the ejection 

 of its saliva. In many, the innermost tunic of the stomach, after great 



* Spallanzani Versuche uber die Verdauungsgesch, p, 36. Reaumur, M6m.de 1'Acad. 

 des Sc. de Paris, A. 1752, p. 472. 



