348 
Psyche 
Silk Glands 
[December 
The tracheae to the silk glands are small branches from 
the tracheae supplying the fat bodies and alimentary tract. 
T only found them springing from the tracheae in the second 
and third segments of the abdomen. (Fig. 30). 
Malpighian Tubules 
Two malpighian tabules on each side extend forward along 
each side of the alimentary tract from the caudal part of 
the body to opposite the fourth abdominal spiracle, where 
they turn and run backward. In the sixth, seventh and 
eighth abdominal segments, but mostly in the last two, the 
tubules become very convoluted and intertwine, and their 
individual characters are lost in the tangle. 
Although carefully sought, no tracheal connections with 
the Malpighian tubules were found, except in the seventh 
abdominal segment. Here small branches arising from the 
trachea supplying the fat bodies and alimentary tract were 
traced to the walls of the Malpighian tubes. (Fig. 30). 
Figure 31 is a sketch of a branch broken from the supply- 
ing trachea to the alimentary tract which showed very 
plainly the small tracheal branches to a urinary tube. 
Circulatory System 
The circulatory system consists of a delicate tube in the 
dorsal part of the body. This is supplied by the ends of 
the large branches of tracheae that also supply the dorsal 
muscles and the fat lying between them and the body wall. 
The tracheal endings in the circulatory organ are very 
fine, not numerous, and somewhat difficult to see. 
Near the eighth abdominal spiracle several of the branches 
break up into a great number of very fine tracheae (Fig. 
32). These fine tracheae lie in, or on, a membrane. They 
are not connected with the alimentary tract, except inci- 
dentally, for removal of the tract leaves most of them 
undisturbed. Such structures do not occur in the branch- 
ings from any other spiracle. That they have anything 
