1914] Anatomy of Epidiaspis Piricola. 55 
on various fruit trees. This possibly might be explained as 
being the result of a mechanical stimulus and the disrupting 
of the cellular make-up of the plant, for the long chitinous 
‘ rods that compose the mouthparts pierce and destroy a great 
many cells. This theory seems to be at fault however, in 
that all scale insects do not cause this phenomenon; for 
example, on the apple A. perniciosus causes a very distinct 
reddening while EF. piricola does not. 
The real function of the saliva is undoubtedly not to aid 
in the taking up of the plant juices, but to act upon these 
food properties after they have entered the insect’s body. 
The relationship of the opening of the salivary glands to the 
oesophagus would seem to point to this. The food is poured 
into a common chamber at the base of the proboscis (Plate 
XIII, Fig. 12-c) passing on through the slender oesophagus 
(12-e) into the stomach. 
The posterior part of the pharynx is a decidedly chitinized 
structure, apparently valvular, to which a number of powerful 
muscles (Fig. 12-f) are attached, and whose function it is 
to help force the food forward, through expansion and contrac- 
tion of the walls of the oesophagus. These muscles are attached 
to the ventral wall of the insect, and undoubtedly act in con- 
junction with the large retractor muscles found directly above 
the pump-like cylinder of the mouthparts (Plate XIII, 
Fig. 12-b). 
In the main the long, slender oesophagus resembles a 
capital letter U running forward from the chitinized pharynx 
parallel to the ventral wall (Plate XIII, Fig. 12-e) of the insect 
to about that point corresponding to the cephalic region of 
the chitinous box-like framework of the mouth-parts. At 
this point it turns toward the dorsal surface, passing between 
the two circum-oesophageal commissures close to the base 
Gfethe. brain. ~ Mere the tube turns parallel to the center, 
emptying into the stomach at a point just posterior to a vertical 
line that would run through the mentum (Plate XIII, Fig. 8). 
This tube is cylindrical in outline and it may be distinguished 
in sections from the surrounding tissue by the minute, circular 
cells, of which it is composed. 
