THE @SOPHAGUS, STOMACHS AND INTESTINES. 409 
numerous small vessels, which apparently perforate the quasi- 
cartilaginous tissue of the plug, which thus affords a rare 
exception to the rule that the trachee do not penetrate into 
the substance of the organs which they supply. 
Functions of the Proventriculus—Many opinions have been 
held with regard to the functions of the proventriculus. It is 
undoubtedly homologous with the gizzard of manducatory 
insects, and it may serve for crushing soft, semi-fluid food. 
Weismann asks if it may not be regarded as glandular, but 
such a view is in no way suggested by its structure. More 
recently Emery has ascribed a suctorial function to the pro- 
ventriculus in Ants (Formicide) [169], which closely resembles 
that of the Diptera. The arrangement of the plug, which 
resembles the plunger of a pump, lends some support to this 
view; but, on the whole, I am inclined to think it is a gizzard 
and nothing more. 
The Proventricular Ganglion differs but little from the same 
structure in the larva. It consists of large ganglion cells, and 
lies in front of the proventricular cesophagus. It gives off 
numerous nerves to the chyle Stomach, proventriculus, and 
cesophagus. 
The Chyle Stomach commences in front above the proventri- 
culus, traverses the thorax, enters the abdomen beneath the 
mesophragma, and curves upwards and backwards in the 
middle line ; at the posterior margin of the second abdominal 
segment it deviates to the right, and after a short course 
terminates in a narrow pylorus, which enters the proximal 
intestine. 
The thoracic portion is covered by small hemispherical 
projections, except at its anterior extremity, which is smooth 
like the abdominal portion. Hence the chyle stomach may be 
said to consist of three parts or segments: the caput, the 
thoracic or intermediate part, and the pyloric extremity or 
abdominal part. The muscular coat of the caput and the 
pyloric parts of the organ is continuous; but in the interme- 
diate portion its external longitudinal coat is arranged in six 
longitudinal bands, whilst the circular fibres are arranged in 
