42 On the Uses of the Dorsal Vessel. {Juxy, 
animals. ‘This circulation is still more evident in the mantes than 
in the genera that we have described. The air taken in by the 
branches of the arterial trachez in the stigmata, is spread, by 
means of their common trunks, into the branches of the pulmonary 
trachee which carry it to their principal trunks, where it is taken 
up by other ramifications, and distributed in all parts of the body, 
When the decarbonization of the blood is effected, the remaining 
oxygen, the azote, and the carbonic acid, are driven out by the 
contraction of the elastic trachee, These gases may either take the 
road by which the air entered, of a different one. All parts, then, 
enjoy the impression of air; and the pulmonary trachez are des~ 
tined to serve as a reservoir, that this impression may be for some 
time independent of the inspirations and expirations. 
The locusta exhibits likewise two orders of trachez, but their 
situation is different from what we described as that of the mantes. 
The pulmonary tracheee extend in a straight line from one extre- 
mity of the body to the other, always keeping towards the middle 
and upper part of the body, They originate above the cerebrum, 
give some branches to that organ, then proceed to the eyes, sending 
different branches to the organs situated in the head. 
These traches penetrate into the corcelet through the foramen 
occipitale, approach each other by degrees, and become gradually 
parallel, giving out a branch to the first pair of legs. When they 
come to the thorax they give out different branches, some of which 
go to the two last pair of legs, and others to the muscles of the 
thorax. _When they reach the abdomen their diameter diminishes, 
though they receive nine branches from each side, furnished them 
by the arterial trachee. ‘These tracheze then extend to the extre- 
mity of the body, giving out a certain number of ramifications’ to 
the dorsal vessel. 
The pulmonary tracheve are very conspicuous in this genus ; but 
the contrary is the case with the arterial. Originating below the 
cerebriform ganglion, they distribute themselves to different parts 
of the head, giving in particular numerous branches to the muscles 
of the head. They extend in the corcelet by two common trunks, 
which go along the side of the body. But when they reach as far 
as the first pair of legs, they become considerably larger, form a sort 
of tubular cavity, and take air immediately by a large oval opening or 
stigma situated in that part. This trachea, the diameter of which 
is very considerable, extends to the extremity of these legs. Be- 
sides this great branch, the arterial trachez furnish other ramifica- 
tions to the muscles, and which bring air to the trunk of the pul- 
monary trache. The arterial trachese continui* win the thorax and 
abdomen by two common trunks, send branches to the legs, the 
pulmonary trachece, and the muscles of the thorax. 
The arterial tracheze become very complicated in the abdomen. 
By their internal side they give off 16 principal branches, 12 of 
which proceed in pairs, while the other four ave simple. The first 
branch is simple: at first very small; it inereases suddenly, giving 
