STUDIES ON THE RESPIRATION OF INSECTS. 
I. THE GASES AND RESPIRATORY PROTEINS OF INSECT BLOOD. 
RIcHARD A. MuttTKowskI, Ph. D. 
(Contribution from the Zoological Laboratory of the University 
of Idaho, Moscow, Idaho). 
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I. INTROLPUCTORY. 
The following paper aims to present certain phases of 
investigations on the respiration.of insects. In a recent article 
(see Bull. Brooklyn Ent. Soc., 15, pp. 89-96, 131-140) I called 
attention to the fixation of oxygen by the blood of some aquatic 
insects. ‘‘In a few rare cases,’’ it was stated (p. 94), “‘the 
carrier is colored. Thus, in some species of Chironomide, 
the pigment is hemoglobin, like that of Vertebrates, except that 
it is found in the plasma, not within the corpuscles. * * * 
The oxygen diffuses through the epidermis just as in the case 
of vertebrates, and is fixed by the hemoglobin or other carrier 
(perhaps hemocyanin?) in the blood. Just what this other 
carrier may be is not definitely ascertained. But by far the 
larger number of aquatic insects have no visible colored carrier 
or respiratory pigment. Thus, for example, Trichoptera larve, 
the larvee of Simulium, of Culicide, and of most Chironomide, 
have gill pouches, usually placed at the caudal end, but all 
without any visible indication of a respiratory pigment.”’ 
As at present understood, respiration among Tracheates 
proceeds directly; atmospheric oxygen is led directly to the 
cells by the tracheae, while the blood acts primarily in the 
transportation of food and metabolic products. The question 
whether or not the blood may play a certain part in the trans- 
portation of gases is a point that merits investigation. 
The following experiments on this subject were performed 
during spring, summer and fall of 1920, although some earlier 
observations are included in this paper. 
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