STRUCTURE OF THE DIGESTIVE CANAL. 
209 
are not quite sufficient. The descriptions, both general and histological, 
refer to the locusts unless expressly stated to refer to the cricket. 
The best method with which I am acquainted for readily obtaining 
a general view of the course and divisions of the digestive tract is the 
following : Place a female (a male will do, but is not quite so good) in 
alcohol of about 50 to 60 per cent, for from 12 to 24 hours; then 
put it in strong alcohol (90 per cent.) for a day or longer; then, with a 
sharp razor, cut it carefully into halves along the median line, so as to 
have the right and left sides separately. Lay the pieces under alcohol, 
and carefully remove the contents of the digestive canal, which will 
then appear very plainly, its course being as represented iu Fig. 45. 
The cavity of the mouth, M, ascends obliquely forward, and is generally 
found filled with a black mass, the coagulated " molasses" which grass- 
hoppers pour out when caught or irritated. The oesophagus, oe., is nar- 
rower, of uniform diameter, it curves upwards and backwards, terminat- 
ing very nearly in the center of the head, where it opens into the very 
large crop, Or. The crop extends through the posterior half of the 
head and the whole of the thorax ; it attains its greatest diameter in 
the prothorax, behind which it descends, tapering off slightly, and end- 
ing in the proventiculus, P. The crop itself is divisible into two dis- 
tinct portions : 1, the anterior (Or. 1 ) lies in the head and prothorax, and 
is characterized by the somewhat irregular transverse ridges on its 
inner surface ; in Caloptenus spretus, the Rocky Mountain locust, these 
ridges are somewhat less numerous and powerful than in 0. femur- 
rubrum ; 2, the posterior ( Or. 2 ), in which the ridges are longitudinal and 
much smaller and closer together than in the front segment ; the shape 
of the posterior division is that of a truncated cone. The proventriculus 
(Kaumagen) P, is so much reduced in the grasshopper that it appears 
as hardly more than the terminal portion of the crop, instead of being 
a large and distinct segment of the digestive canal as in other Or- 
thoptera. The Kaumagen opens into the large " chylific stomach " or 
ventricle, ven., which extends along the ventral surface about half the 
length of the abdomen. At its anterior end it gives off the six blind 
pouches, so long known and so frequently described ; iu a longitudinal 
section only one of these can be seen (Div.) extending forwards under- 
neath the crop. The first part of the intestine I propose to call the 
Ileum, II. It appears at first sight as the direct continuation, or rather 
as the posterior division, of the stomach, from which, however, it is in 
reality perfectly distinct, both by its structure and by its separation 
through a peculiar valve, which I shall describe later. The Malpighiau 
vessels open just underneath and in front of this valve. The second 
division of the intestine I call the colon, col., a name sometimes applied 
by older authors to the rectum. The colon is smaller in diameter than 
any other part of the digestive tube ; it ascends and opens into the 
rectum, B. The rectum extends horizontally directly underneath the 
dorsum ; its diameter is about two-thirds that of the stomach ; its inner 
14 L 
