36 ELEMENTARY STUDIES IN INSECT LIFE 



The Sense of Touch. - If the soft surface of the tips of 

 the palpi (labial and maxillary) of the grasshopper's 

 mouth (Fig. 195, e, g] he examined under the compound 

 microscope., little peg-like structures will he observed. 

 These are connected with nerves which transmit sen- 

 sations of contact, or touch. These organs derive their 

 names from this function. While this sense is localized 

 chiefly in the palpi, it is not confined to them alone. 

 The antenna 1 also serve as tactile organs, but in a varia- 

 ble degree according to their forms, their development, 

 and the habits of the species. Species of beetles with- 

 out eyes find their way about by means of these an- 

 tennae. Our familiar long-horned beetles grope their 

 way among the branches of trees, using their long an- 

 tenna' for the purpose. Insects with long, filiform, 

 many-jointed antenna 1 use them as feelers. Insects 

 with short, stiff antenna 1 , with few joints, evidently 

 do not use them as feelers, and so do not have the 

 tactile sense of the antenna 1 developed in such a high 

 degree. In many insects the extremities of the limbs 

 also have nerve cells which convey impressions of touch. 

 The membrane underlying the chitinous covering of 

 insects is sensitive to touch, so that nearly every por- 

 tion of the insect's body perceives contact with foreign 

 bodies. 



The Sense of Taste. The sense of taste has to do with 

 the determination of the character of matter presented 

 as food, and so the organs of taste naturally lie in the 

 vicinity of the mouth. Of the nerves of taste, some are 

 to be found on the palpi of the mouth, situated with the 

 tactile nerve cells, and others on the membranes of the 

 mouth. This sense is verv eloselv connected with the 



