1929] 
Tracheal System of Pyrausta nubilalis 
347 
mass on each side of the alimentary tract in the forward 
end of the thorax; a large mass which extends across the 
thorax below the alimentary tract, and which, therefore 
lies on both sides of the tract as well as beneath it; next 
come two large masses which largely fill the cavity of the 
abdomen; two masses, one on each side of the alimentary 
tract in about the seventh abdomnial segment ; and a large 
mass in the caudal end of the body which lies on each side 
of the alimentary tract, and ventral to it. The large middle 
masses, one on each side, extend from about the first to the 
seventh abdominal segments; they are made up of large 
lobes, and each segment apparently has a lobe lying in it. 
No definite distribution of these bodies is made here with 
regard to the individual body segments, either in the thorax 
or abdomen, since they overlap each other. These are the 
large masses of fat that have been said to be storage of 
nutriment for metamorphosis, not the fat tissue about the 
body organs. 
The first thoracic mass gets its air supply from the branch 
of the main trachea that also sends a branch to the apex 
of the diamond, a branch to the leg, and one to the wing- 
bud. Apparently the second thoracic fat body receives its 
trachea from the same source. 
From the tracheal branches arising from the main long- 
itudinal tracheal trunk near the spiracular tracheae in the 
second to sixth abdominal segments, and which supply the 
alimentary tract, branches that supply the lobes of the lar- 
gest fat body originate. The tracheae from near the second 
and third spiracles apparently each supply a lobe of the 
fat body. The tracheae arising near the fourth, fifth and 
sixth spiracles send branches into the lobes on each side 
of them, one forward, and one backward. 
The supply to the fat lobe in the seventh segment is ap- 
parently a single branch from the trachea to the alimentary 
tract. The fat body in the eighth segment receives a branch 
from the tracheae that run to the digestive system from 
each side of the body. 
To reach the alimentary tract the tracheae from the spir- 
acles in the second to eighth segments cross the fat bodies 
dorsally. 
