MR. NEWPORT ON THE RESPIRATION OF INSECTS. 
561 
Some of these media affect respiration much sooner than others, which eventually are 
more fatal to the insect. Thus the larva of Papilio urticae , Linn., gave indications of 
life much longer in carbonic acid gas than in hydrogen, but was much longer in 
recovering from the pernicious effect of it when again exposed to the open air ; while, 
on the contrary, the perfect insect became motionless much sooner in carbonic acid 
than in hydrogen. The larvse of this insect were also much longer in recovering from 
submersion in water than from confinement in hydrogen, from the effects of which 
they began to recover immediately they were exposed to the open air. I invariably 
found that if hydrogen be diluted with only a very small proportion of its volume of 
atmospheric air, it is capable of being respired by insects for many hours. Insects 
generally recover from the effects of confinement for several hours in hydrogen, or 
water, upon exposure to the open air, although they may appear to have been com- 
pletely destroyed. These media exert no noxious influence whatever upon the insect, 
but asphyxiate exactly as they affect vertebrated animals, simply by the absence of 
oxygen. Water, however, appears to have a twofold effect upon the insect, first by 
the absence of oxygen, and next by its depriving the insect of its natural heat, and 
lastly by the great degree of cold, or further abstraction of heat, produced by the 
evaporation which takes place from the surface of the insect when again exposed to 
the air for recovery. This latter circumstance may perhaps account for the greater 
length of time which elapses before reviviscence takes place after confinement in 
water than after confinement in hydrogen. A larva of Papilio urticae, Linn., which 
had been confined in hydrogen for more than twelve hours, began to revive in the 
course of two or three hours when again exposed to the open air, although it did not 
entirely recover its locomotive powers in a much longer period. A larva of the same 
species perfectly recovered in half an hour after being submerged in water for more 
than two hours. The larva of the common Drinker Moth ( Odonestis potatoria, Steph.) 
perfectly recovered in one hour and a half, after being submerged for two hours and 
a half. The perfect female of the same species, after submersion for a similar length 
of time, perfectly recovered in less than an hour at a temperature of 73° Fahr. But 
this speedy reviviscence does not take place after confinement in carbonic acid, 
nitrous acid, and chlorine gas. Carbonic acid does not affect the respiration of 
insects so immediately as water, but ultimately it suppresses it much sooner ; and 
although the individual gives signs of reviviscence rather sooner after confinement in 
carbonic acid than after submersion in water, it is much longer before it has com- 
pletely recovered from its effects. Nitrous acid gas and chlorine seem at first to 
affect respiration about in the same degree, at least the symptoms are generally first 
apparent in about the same length of time. The first effects produced upon insects 
by these gases are generally observable in from five to ten seconds, although it is from 
fifteen to thirty seconds before the insect begins to make violent efforts to escape, 
while it seldom continues to give signs of animation for longer than from two to 
three minutes and a half. But the secondary effects of these gases are different. 
4 c 
MDCCCXXXVI. 
