388 



FURTHER OBSERVATIONS ON THE EMERGENCE 



OF DRAGONFLY-LARY^ FROM THE EGG, 

 With Special Reference to the Problem of Respiration. 



By R. J. TiLLYARD, M.A., B.Sc, F.L.S., F.E.S., Linnean 

 Macleay Felloav op the Society in Zoology. 



(Five Text-figs.) 



Tn March, 1014, I was fortunate eriougli to observe the process 

 of hatching- of some larv?e of Annx papiiensis Burm., and was 

 able to discover soni(^ intei^esting facts with regard to the pro- 

 nymphal stage, the nature of the pronymphal sheath, the action 

 of the peculiar organ which I have termed the cephalic heart, 

 and the nietliod by which gas first appears in the tracheal system 

 of the emerging larva. These observations were published in a 

 condensed form in a short papei^,*read at the British Association 

 Meeting in Sydney, on August 25th, 1914. Last year, when 

 studying the problem uf the physiology of respiration in these 

 aquatic larvse, I was struck with the importance of the question 

 as to how the tracheal sy.stem first becomes filled with gas, and 

 the possibility of a causal connection between the action of the 

 cephalic heart and the expulsion of the blood from the tracheal 

 tubes of the emerging larva. In a recent paper,! I have shown 

 the importance of these questions as part of the larger question 

 of the phj^siology of respiration in aquatic larvae, and, in par- 

 ticular, their bearing on what I have termed the " Difivision 

 Theory" of Aquatic Respiration. 



The opportunity of some further research on these difiicult 

 problems occurred on March 18th of this year, when I obtained, 

 from the river at National Park, a piece of a large stem of the 



* Report of the British Association for the Advancement of Science. Aus- 

 tralian Meeting, Sydney, August, 1914, pp. 424-425 (191o). 



These Proceedings, 11)15, xl.. Part 3. pp.422-437, Plate xlvii. 



