DIGESTIVE SYSTEM OF PERIODICAL CICADA. 2OI 



have been made, extending over a series of years, with an effort 

 to correlate them with the clearly established anatomical and 

 morphological features already described. In this connection 

 will also be reviewed some physiological results of recent times 

 which seem to have intimate bearings upon the immediate 

 problems before us. While there has been intimate and continu- 

 ous cooperation and mutual aid between the writers of this 

 paper, in almost all phases of the research, it is frankly stated, 

 however, that each is independently responsible for his own 

 contribution. 



The critical interest of the senior author in the morphology 

 and physiology of this insect began over twenty-three years ago 

 at which time its emergence in June, 1899, afforded a novelty in 

 laboratory material which was presented before a large class in 

 zoology. While in the external morphology of the insect there 

 was ready recognition of the general equivalents, or homology, 

 already familiar from laboratory studies of crickets and grass- 

 hoppers, it was quite otherwise when dissection was undertaken 

 and a study of the internal anatomy was attempted. Here it 

 was soon apparent that conditions were so different from any- 

 thing before studied as to be puzzling in the extreme, and it was 

 decided that this part of the subject was beyond profitable 

 attempt at anything more than a general, and rather superficial 

 survey, especially as it came in the hurried closing days of the 

 college year. At a later time this problem was assigned to a 

 graduate student, R. L. Henderson, reference to which was 

 made by the junior author in his previous paper. The generally 

 accepted view among entomologists was that this insect seldom 

 or never feeds during adult life, and in part this led likewise to 

 the view that the digestive organs were more or less degenerate 

 or even atrophied. Such was my own conclusion from the pre- 

 liminary study above referred to, and presented in a paper read 

 before the County Academy of Science in whose proceedings the 

 latter appeared in print. When Henderson undertook the work 

 assigned to him just cited above, he was early forced to discredit 

 my earlier conclusions on this point; and while unfortunately 

 he did not live to complete his research, some of that which he 

 left in manuscript shows that he had obtained clear evidence of 



