544 STATE BOARD OF AGRICULTURE. 



says lie has known certain beetles to recover after having been immersed 

 in spirits for twelve hours. 8org/ 1805, relates many experiments on 

 insects confined in air, carbon dioxide, oxygen, etc.. all of which he 

 thought went to show' that insects use oxygen and give off carbon 

 dioxide, but that they can endure on little oxygen. Some of them as 

 Papilio crataegi, this author says can use nearly all the oxygen out of 

 a limited quantit.y of air. G. R. Treviranus- in 1814 says that insects 

 show great variation in their dependence of life upon the passage of 

 air into the respirator}^ system. ''Es findet aber unter den Insekten 

 eine grosse Verschiedenheit in der Abhiingigkeit des Lebens von dem 

 Zutritt der Luft zu den Respirationsorganen statt." He then relates 

 several experiments with various insects treated either with w^ater or 

 with oil, all of which seem to show that after complete stoppage of 

 the spiracles it is several hours until death results. So far as I can 

 find, he does not tell, anywhere, what kind of oil he used. Finally 

 as early as 1670, Robert Boyle^ made a long series of experiments in 

 which he confined different animals under the receiver of his air-pump. 

 He tells how grasshoppers, gnats, caterpillars, beetles, ants and flies, 

 when confined in as nearly a vacuum as he could obtain for several 

 hours, recovered after having been again returned for some time to 

 fresh air. 



It was no longer doubted, therefore, in this study, that insects are 

 hard to suffocate but the hare possibility still remained that the oil 

 sprays might plug the tracheae effectually enough for the required 

 length of time, to do just that thing. 



Experiments were arranged which proved conclusively that carbon 

 dioxide and oxygen can diffuse slowly through thin layers of kerosene. 

 About 80 c. c. of carbon dioxide were confined in a receiver above a 

 layer of kerosene (nearly one-quarter of an inch thick) which floated 

 on water. After six hours, less than half the carbon dioxide was visi- 

 ble. The remainder had been absorbed by the water through the thin 

 layer of oil. If, now, air were placed instead of the carbon dioxide 

 of the last experiment and the water beneath the oil substituted by a 

 good absorbent of oxygen (as potassium pyrogallate), the oxygen of the 

 confined air became slowly absorbed. 



But still, the fact that these two gases can pass slowly through a 

 film of oil did not remove entirely the possibility that death to an in- 

 sect might occur through a stoppage of the spiracles by kerosene. The 

 diffusion of gases might not be rapid enough to maintain life. On that 

 account, search was made for an oily substance, as capable of plugging 

 the tracheae as kerosene, but from which insects would recover after 

 treatment. It was found that if healthy specimens of Passalus cornutus 

 were dipped into pure oleic acid (tinged with Sudan III for a marker) 

 for two minutes until all the larger tracheae were filled, the insect 

 would become apparently lifeless as if drowned. When removed at 

 once in this condition and all superfluous oil taken up with good absorb- 

 ent paper, the insect would begin to revive after ten to fifteen minutes. 

 Shortly after that, respiratory movements would start and in a few 



1. Sorg; Disquisifiones Physiologicae circa KcbijiTalioucDi lubectoruiii et Venniiiin; 1S05. 



2. Treviranus, G. R.; Biologic odcr Phiiosopliie der lebenden Natur fur Naturforscher iiud Acrztc, 

 Vol. IV, 1814, p. 151. 



, .3. Boyle, Robert; The Pliil. Transactions of the Royal Society o London, Vol. V. pp. 497-508, 



