530 The University Science Bulletin. 



tions were interrupted before much data could be obtained. The 

 longest observation was that on a fourth instar, which started mak- 

 ing spittle on a large leaf which could easily be placed under the 

 microscope. It started making spittle at 9:40 a. m. At this time 

 the abdomen was extended in the air, and from the slitlike opening 

 in the anus could be seen to exude a clear fluid, which flowed down 

 beneath the body in the ventral channel or air canal of Sulc. A 

 second or so was spent in ejecting this fluid, and then the insect 

 began dipping the abdomen in and out of this fluid, each time pro- 

 ducing a bubble. It did this for ten times, and then the abdomen 

 was lifted high in the air twice and the terminal plates were spread 

 far apart. When a number of bubbles was produced the abdomen 

 was pulled beneath them and then brought up through them so that 

 they were separated and pushed on each side of it. When reaching 

 after air the plates were spread far apart, but at the surface of the 

 spittle they came together. The farther out the abdomen was ex- 

 tended and the slower the movements the larger the bubbles were. 

 The abdomen was next pulled down deeply in the spittle and a few 

 small bubbles were produced. Again the nymph rested for a minute 

 or so, while more fluid flowed from the anus. At times the nymph 

 kicked rapi'dly with its two front pair of legs, making the bubbles 

 go to the side, and during the whole performance one front leg was 

 constantly kicking so that gradually the bubbles were worked head- 

 ward. Again it made bubbles, rested for three and one-half minutes, 

 while the body was straightened out until the spittle was all around 

 the side and partly on the side of the head. Another cessation of 

 bubble-making lasted for six minutes. Later the nymph lay almost 

 on one side with the bubbles entirely on the other side. Next more 

 fluid was ejected until the. body was entirely surrounded and the 

 bubbles pushed entirely to the edge of the fluid mass. A rest of ten 

 minutes followed. At 11:10 it had not ceased making spittle, and 

 the insect was still visible, although the entire body was covered by 

 a thin sheet of foam. At 11:45 there was considerable more spittle 

 and the nymph was still working. 



Another nymph was watched. It started making spittle at 8:20, 

 and in fifteen minutes had enough spittle to make a thin covering 

 for its body. 



From a study of the nymphs of Lepyronia it appears that Sulc 

 has described the process more accurately than any of the others. 

 His description seems to differ only in extent from that of Fabre and 

 Morse, both of which consider the two tergal plates of the ninth 



