228 PHYSIOLOGY OF RESPIRATION IN AQUATIC INSECTS. 



Inasmuch as the tracheae pass through the hremocoele. it i= 

 quite within reason to expect that there will be a certain amount 

 of diffusion of oxygen from the air in the tracheae into solution 

 in the blood. Similarly, carbon dioxide from the cells of the body 

 will pass into solution in the blood, and thence diffuse into the 

 tracheal air. This process, purely one of solution in the watery 

 plasma which forms the insectan blood, must not be confused 

 with the carriage of air by hsemoglobin in vertebrate blood, nor 

 is it reasonable to suppose that this process plays more than a 

 most subsidiary part in the respiration of insects. The very 

 presence of the minutely ramifying tracheal system precludes 

 this probability. 



References. 



Bodine, J. H., 1918. — Experimental results in Enallagma and 



Ischniira. Proc. Acad. Nat. Sci., Philadelphia, 'LXX, pp. 



103//. 

 Cullen, A. M., 1918. — Rectal tracheation of Argia putrida larva. 



Proc. Acad. Nat. Sci., Philadelphia, LXX, pp. 75 //. 

 Dewitz, H., 1890. — Einige beobachtungen betreffend dasgeschlos- 



sene Tracheensystem bei insekt larven. Zool. Anzeiger, 



XIII, pp. 400, 525. 

 Dufour, L., 1852. — Observations sur les larves des Libellules. 



Ann. Sciences Nat., Zoologique, 3. Serie, XVII, pp. 63 //. 

 Rich, S. G., 1918. — The gill-chamber of dragon-fly nymphs. 



Journal of Morphology, XXXI. No. 2. 

 Sadones, J., 1895. — L'appareil digestif et respiratoire larvaire des 



Odonates. La Cellule, XI, pp. 273 //. 



