ANATOMY OF THE EARTHWORM. 267 
indeed, this appears most probable, but the properties of the 
secretion cannot be determined. That these three pairs of 
glands are of very vast importance in the economy of the 
worm cannot be doubted, when their proximity to, and con- 
nection with, the great vessels of the body is considered, 
and it is somewhat surprising that they should have escaped 
the notice of previous observers. 
Crop or stomach.—Leaving the cesophageal glands, we may 
follow the course of the alimentary canal, closely adhered to 
by the dorsal vessel and its surrounding granular mass, to the 
sixteenth or seventeenth ring. Here the cesophagus termi- 
nates, and the digestive tube expands into a voluminous heart- 
shaped sac, which may be regarded as a species of stomach. 
Sometimes this organ commences in the fifteenth ring of the 
body, and at other times it occupies only the sixteenth seg- 
ment; this appears to be a matter of indifference, depending 
merely on the growth of the septal muscles. The muscular 
wall is here well developed, and the continual contractions, 
which it performs even after the worm is pinned out for 
observation, show that one of the principal functions it per- 
forms is the propelling of food on its course through the 
alimentary canal. Very numerous blood-vessels are distri- 
buted to its surface, whilst the interior is lined by a loose, 
largely developed mucous membrane. 
Gizzard.—The eighteenth and nineteenth rings of the 
body are occupied by a hard cartilaginous-looking ring, which 
is attached to the muscular sac just described. Its walls are 
very thick, and composed of fibrous tissue much resembling 
the muscular fibre, but they do not appear to be contractile. 
The blood-vessels, which are very freely distributed to the 
surface, are disposed in a transverse direction, and are very 
minute. This organ has been called the gizzard by previous 
writers, though whether its functions are those of a gizzard 
does not appear at all certain. 
Intestine—Immediately attached to the remarkable fibrous 
ring just described is the intestine, which passes throughout 
the rest of the body with very little change in its structure. 
It is a loosely and much plicated tube, with very delicate 
elastic walls, which are so disposed as to occupy a small space 
whilst possessing a large amount of surface. The wall is 
composed of three distinct coats, of which the interior one is 
mucous membrane, with a finely ciliated epithelium; the 
middle, delicate muscular tissue ; and the exterior, a mass of 
yellow cells, forming an olive-brown-coloured investment for 
the whole intestine, which is of the most tender nature, and 
very easily ruptured. The cells, possessing granular contents, 
