OF DIGESTION. 369 



during the peristaltic motion of the stomach through the exterior 

 muscular tunic, and the remainder,, which was not thus passed through, 

 was driven towards the end of the stomach, and here distended the 

 exterior tunic in the circumference of the pylorus. In a cockchafer, 

 whose longer ilium was filled only at certain parts with food, he 

 observed, after the stomach was removed from the body, a continued 

 distending of it at those parts where the food was found. Upon opening 

 the external skin at those parts, the brownish green chyle streamed 

 forth. Rengger also observed the transmission of the chyle through the 

 intestine in larvae, which he opened alive, for, having carefully dried 

 the exposed stomach, he saw it speedily become again moist. 



Upon the chemical inspection to which Rengger subjected the chyle, 

 that he found between the tunics of the stomach, it did not exhibit 

 the alkaline property of the saliva and the gastric juice. In weak 

 acid it formed flocks, as also when exposed to heat, which was dissolved 

 in concentrated sulphuric acid ; but, upon the addition of water, it re- 

 formed flocks. He found similar flocks when he caused the caterpillar 

 to vomit into diluted acid. Hence it appears that the chyle consists 

 chiefly of albumen, which appears to be suspended in water. Rengger 's 

 experiment further confirms this opinion, for he injected water into the 

 stomach of a caterpillar after he had tied up its end, and, upon opening 

 it after a short time, he found the chyle at the anterior end much more 

 full of water than that of the posterior, of which he convinced himself 

 by the coagulation of the albumen by heat. 



From the chyle being transmitted through the tunic at that part of 

 the intestine usually called the stomach, is another reason for not 

 considering it the stomach only, for the chyme alone is prepared in the 

 stomach, from which the chyle is separated in the duodenum and ilium. 

 We must, therefore, consider this portion, as in the lower animals, 

 merely as the simple internal digestive cavity, whence gradually, by 

 metamorphosis, different intestinal parts are produced, which present 

 themselves as the crop, proventriculus and duodenum ; or where such a 

 division of the simple cylindrical nutrimental canal is not found, that 

 that insect has remained stationary upon a lower grade of the organisa- 

 tion of the digestive apparatus. We should thus find within this single 

 class a progressive succession of the perfection of the intestinal canal, 

 for, commencing with the bag of the larvae of the bees, which has no 

 anal aperture, it terminates in the perfect structure of the predaceous 

 beetles, and which corresponds distinctly with the development of the 



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