Earth-Worms in History. 51 
with leaves, apparently to prevent their bodies from coming 
into contact with the cold, damp earth, and by the still other 
fact that they completely close their burrows during the 
winter. 
Some remarks about the structure of the earth-worm now 
appear apropos. Its body consists of from one hundred to 
two hundred almost cylindrical rings, each provided with 
minute bristles. The muscular system is well developed, 
thus enabling these animals to crawl backwards as well as 
forwards, and to retreat by the help of their affixed tails into 
their burrows with extraordinary rapidity. Situated at the 
anterior end of the body is the mouth. It is furnished with 
a little projection, variously called the lobe or lip, which is 
used for prehension. Behind the mouth, internally located, 
is a strong pharynx, which is pushed forwards when the 
animal eats, corresponding, it is said, with the protrudable 
trunk of other Annelids. The pharynx conducts to the 
cesophagus, on each side of the lower part of which are 
placed three pairs of large glands, called calciferous glands, 
whose function is the secretion of carbonate of lime. These 
glands are very remarkable organs, and their like is not to 
be found in any other animal. Their use is connected in 
some way with the process of digestion. The cesophagus, 
in most of the species, is enlarged into a crop in front of the 
gizzard. This latter organ is lined with a smooth, thick 
chitinous membrane, and is surrounded by weak, longitudi- 
nal, but powerful transverse muscles, whose energetic action 
is most effectual in the trituration of the food, for these worms 
possess no jaws, or teeth of any kind. Grains of sand and 
small stones, from the one-twentieth to the one-tenth of an 
inch in size, are found in their gizzards and intestines, and 
these little stones, independently of those swallowed while 
excavating their burrows, most probably serve, like mill- 
stones, to triturate their food. The gizzard opens into the 
intestine—a most remarkable structure, an intestine within 
an intestine—which runs in a straight line to the vent at the 
