2/6 C. H. TURNER AND E. SCHWARZ. 



how often in recent years doubt has arisen as to the ability of 

 insects to hear, it has been largely maintained that they possess 

 an auditory sense, and for the following two reasons: (i) the 

 ability of many insects to produce sounds as a part of their normal 

 behavior; (2) the possession by insects of organs which struc- 

 turally seem fitted to act as receptors of sound waves. 



Students interested in the morphological method of investi- 

 gating this question will find the paper by Radl ('05) intensely 

 interesting. After epitomizing the work by Lee ('83, '85), by 

 Graber ('82), and by Weinland ('91), he states that, on a priori 

 grounds, he doubted the assumptions of Graber; but that certain 

 experiments had convinced him that insects have a crude auditory 

 sense. In support of his contention, he offers the following 

 reasons. 



1. Graber is inaccurate when he claims that the chordotonal 

 organs are located rigidly between two immovable parts of the 

 body; for the proximal end is attached to an indifferent part of 

 the body, while the distal end is in close proximity to one or more 

 muscles. 



2. The chordotonal organ cannot function like a string attuned 

 to a certain pitch; because it expands and contracts. 



3. All of the chordotonal organs examined are attached at 

 each end to a chitinous framework and the nerve penetrates 

 from the side. 



4. The chordotonal organs resemble somewhat those muscles 

 which occur especially in the limbs of the Arthropoda muscles 

 which terminate in long tendons. 



5. No chordotonal organ is found in either the Myriapoda or 

 the Arachnida. 



6. Chordotonal organs are found in some insects for which a 

 sense of hearing could have no significance. They are well 

 developed in caterpillars; even in those of the Tortricidae, which 

 spend the entire larvel period inside of some fruit. They are 

 also well developed in the internal parasites of certain insects. 



7. All attempts to determine experimentally that insects react 

 to pure and simple tones have yielded negative results : however, 

 i-t is comparatively easy to evoke responses of insects to shrill 

 noises, such as the voice of a cricket or the screech produced by 



