THE GANNET'S ANATOMY 519 



have given time and thought to the air-sacs of birds, but 

 possibly no one has devoted so much attention to these 

 singular reservoirs as Mr. Bruno Miiller, whose conclusions 

 as given in the " Smithsonian Miscellaneous Collections " 

 (1908, Vol, IV., p. 365) are the results of long and patient 

 investigations. 



In Germany, also, a very elaborate study of birds' air- 

 sacs has been undertaken by H. Strasser and other 

 anatomists, while England has not been behindhand, so 

 competent an authority as Dr. H. Gadow having handled 

 the subject in the " Dictionary of Birds " (1893-6, p. 3) 

 in his usual precise manner. Much information is also 

 given in the " Proceedings of The Zoological Society " 

 (]830, p. 90 ; 1882, p. 560 ; 1883, p. 141 ; 1884, p. 543 ; 

 1886, pp. 145, 178), as well as in Pycraft's "History of 

 Birds" (1910). 



Reference may also be made to Mr. Pycraft's description 

 and figure of the Cassowary's air-sacs in "The Transac- 

 tions of The Zoological Society " (1901, p. 252 and 

 Plate XIV.). 



Dr. Gadow's description of what air-sacs are, will be the 

 best preface for any remarks which I am able to offer : — 



" Air-sacks (or sacs) are membranaceous receptacles which 

 communicate with the cavities of the respiratory organs or 

 passages, and can through them be filled with air." 



