insects: their ears and eyes. 159 



ties, and may govern their instincts and actions. Among 

 such we may mention, conjecturally, the comparative 

 moisture or dryness of the atmosphere, delicate changes 

 in its temperature, in its density, the presence of gaseous 

 exhalations, the proximity of solid bodies indicated by 

 subtle vibrations of the air, the height above the earth 

 at which flight is performed, measured barometrically, 

 the various electrical conditions of the atmosphere ; and 

 perhaps many other physical qualities which cannot be 

 classed under sight, sound, smell, taste, or touch, and 

 which may be altogether imperceptible, and therefore 

 altogether inconceivable, by us. It is probable, however, 

 that the antennae, are the organs in which the sense of 

 hearing is specially seated; a conclusion which has long 

 been conjecturally held, and which is confirmed by some 

 observations recently made on the analogous organs in 

 the Crustacea^ which I will allude to more particularly 

 presently. 



The forms which are assumed by the antennae of Insects 

 are very various; and I can bring before you only a very 

 small selection out of the mass. One of the most simple 

 forms is that found in many Beetles, as in this Carabas, 

 for example. Here, each antenna is composed of eleven 

 joints, almost exactly alike and symmetrical, each joint a 

 horny body of apparently a long-oval shape, polished on 

 the surface, but not smooth, because covered with minute 

 depressed lines, and clothed with shaggy hair. There is, 

 however, a slight illusion in the appearance : it seems as 

 if the dividing point of the joints were, as I have just 

 said, at the termination of the oval, but when we look 

 closely we see that the summit of each oval is, as it were, 

 cut off by a line, and by comparing the basal joints with 

 the others, we see that this line is the real division, that 

 the summit of the oval really forms the bottom of the 

 succeeding joint, and that the constricted part is no 

 articulation at all. The first, or basal joint (called the 



