THE DIGESTIVE SYSTEM OF THE PERIODICAL CICADA, 

 TIBICEN SEPTENDECIM LINN. 



L. M. HiCKERNELL, Syracuse University. 



I. Morphology of the System in the Adult Insect. 



I. Introduction. 



II. Literature. 



III. Material and Methods. 



IV. The Digestive Tube of the Adult Male Insect. 

 V. Relative Conditions in Male and Female. 



VI. Discussion. 



VII. Summary and Conclusions. 



VIII. Bibliography. 



IX. Description of Figures. 



I. Introduction. 



Numerous authors have reported the impossibiHty of fol- 

 lowing the digestive system of the periodical cicada throughout 

 its entire length. Of those who state that it is complete and 

 well organized, none attempts any detailed description. My 

 attention was called to the matter in 1916 by Dr. C. W. Hargitt 

 who had himself been interested in the question of digestive 

 activity in this insect for some years. Dr. Hargitt' s observation 

 dealt particularly with the feeding habits of the cicada. He 

 had also directed a graduate student, R. L. Henderson, in an 

 attempt to work out the morphological details of the enteron. 

 Unfortunately before this work was completed the death of 

 Mr. Henderson intervened. 



In the present work I have constantly consulted with Dr. 

 Hargitt, but the entire responsibility for the morphological 

 details herein presented lies with me. A further publication, 

 in which Dr. Hargitt has the major interest, dealing with the 

 physiological aspects of the problem, will appear shortly. 



II. Literature. 



There has been much lack of agreement in the literature 

 as to whether the cicadas do or do not feed and this question 

 has led in turn to the inquiry as to whether the digestive tube 

 is atrophied in the supposed cases of non-feeding. Marlatt 

 (1898) in his summary of the habits of the insect, says that dur- 

 ing its aerial existence "it seldom, if ever, takes food." In. 



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