124 THE VITAL FUNCTIONS. 



is exerted. A similar use may be assigned also 

 to the organs denominated Palpi, or AntennulcB 

 (p, q), which are jointed filaments, or processes, 

 attached to different parts of the mouth, and 

 most usually to the maxillae and the labium ; 

 the former (p) being termed the maxillary, and 

 the latter (q) the labial jxilpi. In addition to 

 these parts, another, which, from its supposed 

 use, has been denominated Glossa, or tongue 

 (g), is also generally found. 



For an account of the various modifications 

 which these parts receive in different tribes and 

 species, I must refer to works which treat pro- 

 fessedly of this branch of comparative anatomy. 

 I shall content myself with giving a single 

 example of the conversion of structure here 

 alluded to, in that of the rostrum, or proboscis of 

 the Cimex nigricornis. This insect belongs to 

 the order Hemiptera, which has been usually 

 characterised as being destitute of both man- 

 dibles and jaws, and as having, instead of these 

 parts, an apparatus of very diflferent construc- 

 tion, designed to pierce the skin of animals and 

 suck their juices. But Savigny, on applying 

 the principles of his theory, has recognised, in 

 the proboscis of the Cimex, the existence of all 

 the constituent elements that are found in the 

 mouth of insects formed for the mastication of 

 solid food. This proboscis consists of four elon- 

 gated filaments, contained in a kind of sheath : 



