494 Wisconsin Academy of Sciences, Arts, and Letters. 
anterior and the tip of the “tube” reaches the surface of the 
water first. If a specimen of Banantm in this position is 
watched, it is noticed that soon after the tips of the caudal fila¬ 
ments reach the surface a film of air is seen between them and 
this can be either the air expelled from the body or the fresh air 
being drawn into the trachae. We carried on a few experiments 
to determine the necessity of the “respiratory tube” and what 
effect an injury to this part would have upon the insect. Sev¬ 
eral specimens were first taken and the “tube” of each cut par¬ 
tially off, the amount removed being different in each case. 
These were then replaced in small aquaria and all of them lived 
for several days, no difference in the length of life being notice¬ 
able between these and normal specimens living in the same or 
similar aquaria. Two specimens had the entire “tube” re¬ 
moved, and also the stigmata on the filaments and a small part of 
the trachea and yet the insects lived for a number of days. Two 
normal specimens were placed each in a bottle of water and in one 
case a cork was placed so that it rested on the surface of the water, 
in the other paper was used. One- of these died in four or five 
hours and the other was not: seen again until the next day, when' 
it too was dead. The length of the “tube” allows the insects to 
remain farther away from the surface and the better concealed, 
but respiration can be carried on just as well with a very short 
as with a long “tube.” An examination of the caudal filaments 
after they have been cleared and mounted shows that the stig¬ 
mata which are used by the insect when submerged are situated 
one near the proximal end of each filament:. Comstock (1) says 
that the filaments conduct “the air to two spiracles situated at 
the caudal end of the abdomen,” a view not given by Locy (5) 
who correctly says that the stigmata are on the filaments. 
From the stigma at the base of each filament there passes 
forward a trachea which, surrounded by a, part, of the fat body, 
extends through the abdomen, giving off a number of branches 
to supply the different parts of the body. (PI. XXXV, Fig. 12.) 
There are on the abdomen three pairs of stigmata, a pair to 
each of the following segments ; the third, fourth and fifth. 
When the abdominal tracheal tubes reach the posterior end of 
the metathorax, each divides into 1 two branches, the outer of 
which bends towards the side of the body and connects with a 
stigma which is situated at the posterior lateral edge of the meta- 
thorax. The inner loops bending slightly towards the central 
