MR. NEWPORT ON THE RESPIRATION OF INSECTS. 
551 
substance is brought into contact with them, which distinctly proves the possession 
of a voluntary power over the muscles connected with them, and which, as before 
shown, are supplied from the moto-sensitive columns. 
Quantity of Respiration. 
The very important fact established by Dr. Edwards in the higher animals, that a 
greater quantity of oxygen is required in the adult state in proportion to the capacity 
of the respiratory apparatus than in the earlier or infant condition of the animal, and 
that in a state of hybernation less even is required than in the infant state, is equally 
true as regards also the air-breathing Invertebrata, particularly the class of insects. 
The larva of Ichneumon Atropos, Steph., concealed within the body of the larva of 
Sphinx ligustri, Linn., and preying upon its substance, although provided with mi- 
nute spiracles which lead into extremely delicate tracheae distributed through its 
body, and doubtless maintaining a certain degree of respiration, requires not a twen- 
tieth part the amount of atmospheric air for its support which it requires in its perfect 
condition. The larvae of the wild bank bees, Anthophora retusa, Steph., and Eiicera 
longicornis, Steph., and of many others, confined in their cells in the earth ; of the 
Sand Wasps and Spheges, buried deeply in the soil ; of the Cerambyces and Ptinidce, 
and other wood-boring insects ; and of the Scarabcei, Lucani, Tipulee, and Muscce , 
many of which live in the most noxious and unaerated places, can exist for a very 
long time in situations in which the same insects in their perfect state would soon 
perish. Hence it is clear that a smaller quantity of air is required for the support of 
these insects while larvae than when they have become perfect. The quantity of air 
required for the support of the same tribes of insects varies in like manner in the dif- 
ferent species. 
In the summer of 1832, at the suggestion of my friend Dr. Marshall Hall, I was 
led to inquire whether the quantity of respiration in insects bears any relation to the 
comparative irritability of the muscular fibre in the different genera and states of the 
same tribes of insects ; and I was afterwards led to inquire more particularly into 
the exact amount of respiration in different insects, and different states of the same 
insects, for the purpose of ascertaining what relation, if any, subsists between the 
quantity of respiration and natural temperature of body in these animals. Although 
I was unable at that time to ascertain the exact amount of respiration in the different 
states and species, owing to various causes, such as the variations of the thermometer, 
the degree of excitement or quiescence of the insect, and consequently the uncertain 
amount of air consumed, and quantity of carbonic acid gas produced during the ob- 
servation, yet the results gave a near approximation to the truth, and enabled me to 
form an opinion respecting the real amount in each observation when made under 
similar circumstances. The observations were made in the following manner. When 
a single specimen was employed the cubic bulk of the insect was first ascertained, 
and the insect was then confined in an accurately closed stoppered phial of known 
