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Packard, A. S.— 1898. A Text-book of Entomology. 



Sadones, J. — 1895. L'Appareil Digestif et Respiratoire Larvaire des 

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TiLLYARD, R. J.— 1915. On the Physiology of the Rectal Gills in the 

 Larvae of Anisopterid Dragonflies. Proc. of Linn. Soo. of N. S. Wales, Vol. 

 XL, Part 3, Aug. 25th. 



— 1916. A Study of the Rectal Breathing Apparatus in the Larvae of 

 Anisopterid Dragonflies. Journ. Linn. Soc. London, Zool. Vol. XXXIII. 

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— 1917. The Biology of Dragonflies. Cambridge Zoological Series, Cam- 

 bridge, University Press. 



IV. EXPERIMENTAL RESULTS IN ISCHNURA AND ENALLAGMA. 



BY JOSEPH HALL BODINE. 



(The following paper was written out by Mr. Bodine in nearly the form 

 here presented. Owing to his having entered the war service of the United 

 States, it is unlikely that he will be able to continue these researches for many 

 months. He has placed his manuscript in my hands with the wish that I do 

 with it as I think best. I have made some slight verbal changes, but otherwise 

 the paper represents the author's own observations and conclusions. — Philip 

 P. Calvert.) 



The problem of the physiology of respiration among insects 

 is by no means a settled one and presents a great many obstacles 

 to its solution, especially in certain aquatic stages. 



The types, theories, etc., of respiration found in insects have 

 been much discussed and can be easily learned from any of the 

 more recent text-books of entomology and comparative physiology 

 and hence need not be taken up here. I shall deal entirely with 

 the phenomena among the dragonflies, restricting the problem to 

 the suborder Zygoptera. 



The morphological studies upon the structure of the rectum and 

 caudal gills of the larvae of Zygoptera bring forward several questions, 

 as to the exact function of these parts. 



The organs generally supposed to be concerned in the respiration 

 of these larvae are the caudal tracheal gills, the so-called rectal gills 

 or folds, the body surface and the spiracles. The structure of the 

 rectal gills or folds, especially as regards the distribution of tracheae 

 to the same is discussed in the papers of Calvert, Jamieson, CuUen 

 and Carroll, and need only be referred to here. (The structure of 

 the caudal gills has been described by Tillyard in 1917, in a paper 

 published after Mr. Bodine's work ceased.— P. P. C.) 



Various theories of respiration for these larvae have been pro- 

 posed, some of which are quite conflicting and the remainder are 

 based rather upon philosophical, than physiological, ideas. 



Briefly stated and outlined these theories are as follows: Reaumur 

 (1742) and Roesel von Rosenhof (1749) regarded the caudal gills 



