004 
J. davidSox. 
'File Cornicles. — The cornicles (Riickenrolire of German 
anthoi’S, the Saftliocker of Morclwilko [1895] in Lachnns), 
in common with otlier members of the Pern ph igin ae, are 
greatly reduced in Sckizoneura lanig’era. They consist 
of a pair of small tubercles situated on the dorsal surface of 
the sixth abdominal segment, near its anterior border. Each 
tubercle surrounds a semilunai’-shaped opening, which is 
overhung by a lip-like thickening of the integument, its 
convex border being dircted towards the posterior end of the 
abdomen. 
A section through the body in the region of the cornicles 
(fig. 46) shows that the integument is thickened to form a lip- 
like structure over the semilunai’-shaped fissure (c. 0 .). Two 
bands of muscles (m. cn.) are attached to the integument near 
the opening of each cornicle, and passing to the ventral 
surface of the seventh and eighth abdominal segments, 
control the valve-like movements of this opening. 
Lying in the posterior region of the abdomen is a delicate, 
wax-sac {w. s.), which opens at each side into the cornicles. 
AVheu a living specimen is examined in normal saline solution, 
the wax-sac is seen to contain a pale-yellowish, oily fluid, 
somewhat resembling the fat-globules produced by the fat 
body-cells. In preserved material, however, the contents of 
the sac become hard, and form a conspicuous, whitish, 
refractive mass, which lies in the posterior end of the body. 
This substance is of a waxy nature, soluble in xylol, but in- 
soluble in alcohol, water, and glycerine. In sections mounted 
after treatment with xylol, the delicate wall of the wax-sac is 
seen surrounding the empty cavity of the sac, whose contents 
have been dissolved by the xylol. 
'Fhe question as to the function of the cornicles in aphids 
has occupied the attention of many observers. It would 
appear from the literature that the term “ honey-tubes,” 
which is often applied to these structures, is a misnomer. 
According to the resume of the subject given by Horvath 
(1904), Reaumur (1737), one of the earlier observers, thought 
that these structures had an excretory function. Bonnet 
