228 The habits of a Species of PtyeJus. 



the Aphrophorcc secretes or emits the froth from its body. 

 Thus Dr. Sharp summarizes the older opinion in the 

 following words: — ". . When in the immature stages, 

 certain of them [Oercopidcv] have the art of emitting the 

 liquid in the form of bubbles which accumulate round the 

 insect and conceal it " (1. c. p. 577). Professor Morse shows 

 that when the insect is cleared from the bubbles and 

 placed on its food- plant, " it will crawl quite rapidly along 

 the stem . . . , stopping at times to pierce the stem for 

 the purpose of sucking the juices within, and finally 

 settling down in earnest, evidently exerting some force in 

 thrusting its piercing apparatus through the outer layers, 

 as shown by the firm way in which it clutches the stem 

 with its legs. After sucking for some time, a clear fluid 

 is seen to slowly exude from the posterior end of the 

 abdomen, flowing over the body first and gradually filling 

 up the spaces between the legs and the lower part of the 

 body and the stem upon which it rests. . . . During all 

 this time not a trace of an air-bubble appears; simply a 

 clear, slightly viscid fluid is exuded, and this is the only 

 matter that escapes from the insect. . . . This state of 

 partial immersion continues for half-an-hour or more. . . . 

 Suddenly the insect begins to make bubbles by turning 

 its tail out of the fluid, opening the posterior segment, 

 which appears like claspers, and grasping a moiety of air, 

 then turning the tail down into the fluid and instantly 

 allowing the enclosed air to escape. . . . These movements 

 go on at the rate of seventy or eighty times a minute. 

 At the outset the tail is moved alternately to the right 

 and left in perfect rhythm, so that the bubbles are dis- 

 tributed on both sides of tlie body, and these are crowded 

 towards the head till the entire fluid is filled with bubbles, 

 and the froth thus made runs over the back and around 

 the stem." Many other interesting facts and observations 

 are recorded in this paper which should, I think, be repro- 

 duced in a more accessible form, together with the simple 

 but entirely adequate illustrations. The probability of 

 some accessory aid to respiration by means of thin-walled 

 leaf-like appendages is also discussed. The whole problem 

 of the respiration of the insect enclosed in its mass of 

 froth would be a fascinating subject of inquiry. The mere 

 contemplation of it is enough to bring home the utter 

 improbability of the older view as to tlie origin of the 

 included gas. — E. B. Poulton. 



