84 Elementary Manual of Zoology. 
(2) A narrow gullet. 
(3) A large crop, whieh occupies the greater part of the body 
cavity. 
(4) A little muscular gizzard which is armed inside with six little 
brown teeth something like what we found in the fresh- 
water crab, only on a smaller scale. 
(5) A narrow thin-walled portion (mesenteron), into the front part 
of which a series of large glandular tubes (hepatic ceca) 
open. 
(6) A narrow convoluted portion (proctodeum), which connects 
the mesenteron in front with the anus behind, Notice 
the numerous thread-like seeretory organs (malpighian 
tubes) which pour their secretion into the digestive tract, 
just when the mesenteron joins the proctodeum. 
Notice the little silvery tubes (trachez) which ramify throughout the 
whole body, carrying air from the spiracles at the sides. In some lights 
the students will be able to make out with a lens the spiral filament by 
which the walls of the trachew are supported, but usually a microscope 
is required for this purpose. 
-Now carefully brush away the fat at the posterior end of the abdo. 
men. If the specimen is a female, make out the two sets of slender 
tubes (ovaries), in which can be seen a number of white thickenings, 
which are the eggs. If the specimen isa male, make out the large white 
tults of glandular tubes (mushroom gland), which receive the spermato- 
zoa derived from the pair of minute testes, which the students will not 
be able to make out. 
In the centre line of the abdomen, close to the ventral armour, the 
students will now be able to make out the ventral nerve system. This 
consists of a series of little white nerve masses (ganglia), each connected 
with the next by two nerves, so as to form a chain which extends 
throughout the whole length of the body. ‘Trace this chain as far as 
possible in both directions. Notice the little nerves given off from each 
ganglion, and in dissecting the portion about the neck, try to make out 
the nerves which pass round the gullet, and connect the nerve mass 
which lies in the.bead (supra-cesophageal ganglion) with the front 
ganglion of the ventral chain, Now make a careful drawing of the 
dissection and inark in the names of the organs that have been successfully 
made out. 
DISSECTION OF THE MULBERRY SILK CATER: 
PILLAR. 
Mulberry silk caterpillars (Bombyx) were for a long time culti- 
vated in Majra in the Eastern Dun. They can now be procured either 
from Cashmere, where the large species Bombyx mori is to be had, or 
