METABOLISM OF INSECTS 



543 



It is interesting to note that about 1830 

 the investigators were beginning to im- 

 prove their technique. They were chang- 

 ing the methods of introducing oxygen 

 into the animal chamber; they were find- 

 ing new ways of securing airtight com- 

 partments. In general, apparatus was the 

 big issue and Treviranus quite boldly 

 criticized the methods and apparatus used 

 by Sorg (2.7). Treviranus (32.) studied 

 the gaseous exchange of various animals, 

 including some insects, such as butterflies, 

 moths, flies, and beetles. He calculated 

 the oxygen consumption per kilogram per 

 hour for one of the beetles at a temperature 

 of i3-i5°C. In addition he measured the 

 oxygen consumption and carbon dioxide 

 output of three bees at n.5°C. He found 

 that the honey bee absorbed more oxygen 

 at Z7.5 than at i4°C. 



Newport (19) studied the carbon di- 

 oxide output of insects in various stages 

 of development. He found that the chry- 

 salis of a certain butterfly produced less 

 carbon dioxide than did the larva or the 

 full-grown insect. Spallanzani had pre- 

 viously made this same observation. 



In the classical work of Regnault and 

 Reiset (Z3) no reference is made to tem- 

 perature. They found that z.6z-z.8z 

 grams of carbon dioxide were given off 

 per day by 100 grams of May-beetles and 

 Z.31-Z.58 grams of oxygen consumed, 

 giving a respiratory quotient of 0.8Z-0.79. 

 (Respiratory quotient: Ratio of the num- 

 ber of molecules of carbon dioxide formed 

 in oxidation, to the number of oxygen 

 molecules used.) These investigators 

 found that the silkworm chrysalid con- 

 sumed one tenth as much oxygen per gram 

 of body weight as did the earthworm. 



Butschli (7) studied the effect of tem- 

 perature upon the gaseous exchange of the 

 cockroach fed on different substances. A 

 rise in temperature was followed by a 

 regular rise in gaseous exchange. At 1 5°C. 



the gaseous exchange was twice as great as 

 at 4 , and at 3Z it was seventeen times 

 greater than at 3 . Butschli's findings 

 were in the main confirmed by Vernon 

 (33), although the latter 's figures run 

 somewhat higher than Biitschli's. 

 Vernon measured the milligrams of carbon 

 dioxide given off by the cockroach at 

 2. , io°, zo°, and 3o°C. 



Loeb (15) used the chrysalides of certain 

 butterflies and moths to determine the 

 effect of light on carbon dioxide produc- 

 tion. He found that it had no influence 

 on the output and concluded that its 

 effect on carbon dioxide production was 

 due to an increase in muscular activity. 

 Many experiments have been performed 

 on the gaseous exchange of silkworms. 

 Of these the outstanding ones are those 

 of Luciani and Piutti (18), Luciani and 

 Lo Monaco (17), and Farkas (10). Luciani 

 and Piutti found that at io° the eggs gave 

 off three times as much carbon dioxide as 

 at o°C. During incubation the respira- 

 tory quotient approached unity. A't the 

 time of hatching, the carbon dioxide out- 

 put went up. Luciani and Lo Monaco 

 found in silkworm larvae that there was a 

 decrease of carbon dioxide during rest and 

 a rise of carbon dioxide output during 

 activity. The latter workers were not 

 concerned with the influence of tempera- 

 ture upon the gaseous exchange. From 

 the numerical results of these investiga- 

 tors it was calculated that a silkworm 

 larva gives off 378 cubic centimeters of 

 carbon dioxide per kilogram per hour at 

 room temperature. Farkas determined the 

 gaseous exchange of the eggs and of the 

 larvae at the moment of hatching. The 

 gaseous exchange was high at hatching, 

 but gradually decreased with advancing 

 age. 



Sosnowski (x8) studied the gaseous ex- 

 change of larvae and chrysalides of flies. 

 He did not mention at what temperature 



