550 
MR. NEWPORT ON THE RESPIRATION OF INSECTS. 
much fatigued, while in the natural state, when the insect is undisturbed, the con- 
tractions of the segments, or acts of respiration, seldom amount to one half that 
number. In an extremely wild and irritable little bee, Anthophora retusa, Steph., 
which dies from the most violent excitement and exhaustion in the course of an hour 
or two, after being captured and confined during summer, although plentifully sup- 
plied with food, — the acts of respiration are performed so rapidly that it is almost 
impossible to number them. On one occasion myself and a friend counted two hun- 
dred and forty in a minute. 
The condition of respiration when an insect is recovering from a state of torpidity 
is very interesting. In the beginning of January, on a fine but cold windy day, upon 
examining one of my hives I found many bees which, having ventured abroad when 
the hive was disturbed, were lying torpid and completely motionless in a side box 
that was attached to the hive, when the temperature of the air was about 40° Fahr. 
I removed some of these to a room, the temperature of which was 60° Fahr., and 
they soon gave indications of reviviscence. The first visible signs of returning ani- 
mation were slight twitchings of the tarsi, and feeble contractions of the abdominal 
segments, which gradually increased in frequency, but were at first very irregular. 
At two minutes after the first motions of the abdominal segments, and consequently 
after the acts of respiration were first perceived, the contractions gradually became 
more regular in their occurrence, and amounted to fifty-eight per minute. At the 
expiration of four minutes they amounted to sixty-three, at six minutes to seventy-two, 
at eleven minutes to eighty, at fifteen minutes to seventy-seven, at which time the 
insect began to move the whole of its limbs. At eighteen minutes they amounted 
to eighty-five, at twenty minutes to eighty-seven, at twenty-five minutes to eighty- 
four, at thirty-three minutes to one hundred and two, and at thirty-six minutes to 
one hundred and five ; and when the insect was perfectly recovered, and had been 
for some time in a state of activity, the number of its respirations amounted to one 
hundred and sixty per minute. At thirty-three minutes the insect had regained its 
power of locomotion, and began to move about, and its respiration, which had then 
become more quiet and regular, was still more frequent than in a state of perfect 
health, when it seldom exceeds forty inspirations per minute. 
It is in the pupa state that insects respire less frequently than in any other, and it 
is in this state that I have been able most distinctly to observe the action of the spi- 
racles. When the insect has remained in the pupa state for a few weeks, in a low 
temperature, it passes into a complete state of hybernation, and its respiration, as I 
shall presently show, is almost entirely suspended ; but when the insect has been 
kept in a temperature of 60° Fahr. or upwards, it respires very freely, and the action 
of the spiracles in the pupa of Sphinx ligusiri may sometimes be observed by means 
of a microscope. There are in general about three contractions of the spiracles per 
minute, the intervals between which are very regular. A perfectly healthy and 
vigorous pupa always closes its spiracles whenever any irritating or obnoxious 
