1815.) On the Uses of the Dorsal Vessel. 39 
which establish a communication of superior and inferior ramifica- 
tions, All these trachese enjoy immediately the action of the air, 
and distribute it into the pulmonary trachee. It is from the first 
branch principally that the trachee proceed which spread them- 
selves on the organs of generation, while those of the intestinal 
viscera are furnished successively by the six branches. Besides these 
principal branches, the common trunk furnishes other four, one 
which precedes all the branches, and three which come imme- 
diately after them. ‘The first spreads itself on the superior abdo- 
minal muscles, and upon the intestinal tube. The others, on the 
contrary, give numerous ramifications to the muscles of the abdo- 
men, and particularly to the organs of generation. 
The pulmonary traehez, more constant in their direction, rise 
above the cerebriform ganglion by a common trunk, which divides 
into two principal branches, the upper of which go to the eyes and 
the antenna. The lower extend backwards to the foramen occipi- 
tale, traverse the muscles of the mandibles, and penetrate into the 
corcelet. There they separate a little from each other, give out a 
branch to the first pair of legs, and furnish a very few branches to 
the muscles of the corcelet. ‘These tracheze then make their way 
into the thorax, where they give out two principal branches, which 
terminate in the legs, furnishing some ramifications to the muscles, 
When they come to the abdomen, they approach each other, and 
run near the dorsal vessel, sending out a great number of branches, 
which divide themselves on the external membrane of this vessel, 
During their whole passage we see them almost always sinuous, 
forming from distance to distance semicircles, which touch each 
other by their summits. As we have already explained how these 
trache receive air, we shall not resume the subject again, 
The respiratory organs of the phasme consist equally of two 
orders of trachez, the arterial and pulmonary. ‘These last present 
in the head four principal branches. The superior branches are the 
largest and longest. ‘They furnish branches to the antenn, the 
upper lip, and the mandibles. When these trachew make their 
way into the corcelet, they separate from each other, and unite with 
the branches of the inferior pulmonary trachee to penetrate into 
the first pair of legs, where they spread themselves. ‘The inferior 
branches of the pulmonary trachee are situated below the preceding, 
Their trunks are more nearly straight. All these traches issue 
through the foramen occipitale, and unite in the corcelet, so as to 
form only two principal trunks, more or less near to the dorsa 
vessel, but always accompanying it. When these branches have 
come as far as the second pair of legs, they send them a principa 
branch. The same thing happens when they come to the third 
pair. Whien they enter the abdomen, they proceed still nearer the 
dorsal vessel, to which they send numerous branches. 
The arterial trachew have not a direction so constant as the pul- 
monary. In general, being composed. of bundles of branches, they 
make all parts enjoy the impression of air, which they reecive im- 
