106 M.H.Rathke on the Respiratory Process in Insects. 
render the taking in of any considerable quantity of oxygen from 
the atmosphere unnecessary. Analogous phenomena are pre- 
sented by hybernating Mammalia and Reptiles, as in these, 
during hybernation, respiration is almost entirely suppressed ; 
and nevertheless whilst the fat so abundantly deposited almost 
entirely disappears, some of the other organs, especially the testes 
and seminal vesicles in the Mammalia and the ovaries and ovi- 
ducts also in the Reptiles, are considerably increased in size and 
gradually prepare a great mass of their secretions. It is, as many 
phenomena indicate, the exaltation of nervous action and the 
activity of the muscles that give rise im animals to a greater con- 
sumption of atmospheric oxygen, and therefore to a more rapid 
and powerful respiration, in order to replace the wasted portions 
of the nervous and muscular systems ; far less oxygen is required 
by the lower constituents of the organism to maintain themselves 
in action or even to develope themselves further. 
§ 30. Lastly, the question is to be answered whether insects 
both inspire and exspire the air through all their stigmata. 
Beautiful investigations for the solution of this question are 
to be found in one of Bonnet’s memoirs*. “Bonnet’s principal 
observations are as follows :— 
1. If a Caterpillar be immersed in water so that only the hind- 
most pair of stigmata are left free, it survives this experiment 
for some time, whilst it soon dies if entirely immersed. 
2. It also lives for some time if immersed so that only its 
anterior pair of stigmata remain free. 
3. When a Caterpillar is entirely immersed in water, an air- 
bubble is not unfrequently seen to issue from one or other of its 
stigmata, most commonly from one of the foremost or hindmost 
pairs, and this is then alternately drawn in and pushed out. 
4. When the stigmata of the foremost and hindmost pairs in 
a Caterpillar are clogged with butter, and the rest left free, the 
animal is more uneasy than when the experiment is reversed: 
From these experiments it follows that Caterpillars inspire and 
exspire by all their stigmata, but most through those of the fore- 
most and hindmost pairs. 
Moreover it is inconceivable that the whole mass of inspired 
air should be exspired by other ways than those through which 
it entered the body. This would be in opposition to the entire 
structure of the respiratory system; for in a great number of 
insects the stigmata are so constructed that they cannot be closed 
by the animal, and consequently furnish the air with a means. 
both of entrance and exit. 
* Mem. de Math. et de Phys., vol. v. In Acridium stridulum the stig- 
mata above the intermediate pair of legs appear to exspire only, and not 
to-inspire: . 
