INSECTS IN GENERAL, 



65 



struments, and Knoch imagined that the maxillary palpi 

 were employed in smell, and the labial in taste. But the 

 opinion that they were designed for touch has been embraced 

 by very high authorities, and above all by the Baron him- 

 self, M. Dumeril, indeed, observes that the palpi, though 

 very mobile in the masticating insects, are rudimental or 

 altogether nullified in the suctorial, and their form altogether 

 chang-ed. 



It would appear that the tarsi are very useful organs of 

 touch in many insects, and the best calculated to give them 

 an idea of the nature of bodies. In the majority they have 

 a broad spongy surface, which in flies, &c. applies with 

 great facility to the superficies of an object. In other insects 

 they are considerably elongated, and composed of very mo- 

 bile articulations. In many apterous insects these tarsi are 

 obviously the instruments which they employ to explore the 

 solidity and natvire of the bodies on which they are about to 

 transport themselves. 



Let us noAv bestow a little attention on the nutritive func- 

 tion in these interesting animals. We have already seen that 

 insects admit of two general divisions founded on the mode in 

 which they take their food, whether by suction or mastication. 

 Like other animated beings they derive the elements of their 

 nutrition from organized bodies, or from substances which 

 have already been borrowed by other living beings from 

 brute or inorganic nature. But the modes of alimentation 

 are extremely varied as we shall now briefly explain. 



The kind of food taken by insects varies greatly in one and 

 the same species, at different epochas of its existence. One 

 species is carnassial, or lives on the juices of animals in its 

 first state, and subsequently becomes herbivorous. Another, 

 on the contrary, is first nourished on the debris of vegetables, 

 and afterwards cannot live except on the fluid or solid parts 

 of animal bodies. Some, during a period of their existence, 



VOL. XIV. F 



