DEATn'S-HEAD HAWK -MOTH. 137 



Bible, from the nature of their organization, that 

 any insect can be possessed of a genuine voice, it 

 has been conjectured that the noise is occasioned by 

 the friction of one organ against another, as is well 

 known to be the case with many beetles, grass- 

 hoppers, &c. Reaumur and others accordingly 

 ascribe it to the reciprocal action of the trunk and 

 palpi ; but the sound having been found to continue 

 after these organs were cut off, it must evidently 

 have some other origin. Under the idea that it 

 was connected with the motion of the wings, 

 another observer was led to conceive that its source 

 was two concave scales placed at the base of these 

 appendages, against which the air is forcibly pro- 

 pelled by their rapid motion. M. Lorey, a French 

 physician, maintains that the stridulation in question 

 is produced by the escape of air from a trachea 

 placed on each side of the base of the abdomen, 

 which, when the animal is in a state of repose, are 

 closed by a fascicle of fine hairs. A more recent 

 writer, M. Duponchel, controverts all these state- 

 ments, and gives it as his opinion that the noise is 

 emitted from the interior of the head, in which there 

 is a cavity communicating with the trunk, and near 

 which are placed the muscles by which the latter is 

 put in motion. As M. Lorey, however, affirms that 

 he has heard the sound after the head was ampu- 

 tated, and M. Duponchel makes the same assertion 

 in relation to the abdomen, these various opinions 

 must be considered as irreconcilable, and the matter 

 left to be decided by future investigation. 



