276 INEZ L. WHIPPLE. 



Bruner, the effect of this contraction is to completely close the 

 external nans. My own observations of Diemyctylus and the 

 Ainblystomas made by the aid of a lens do not, however, corrob- 

 orate this statement, since I have frequently seen the external 

 nares fail to close completely during pulmonary respiration, 

 although there is always an almost complete closure. 



As a result of the prolonged depression of the floor of the 

 mouth air is first drawn in through the open nares, as in bucco- 

 pharyngeal respiration. This part of the process is known as 

 aspiration. During the latter part of the act of depression, how- 

 ever, when the external nares are closed, air is drawn from the 

 lungs into the mouth through the opened glottis and the air in 

 the mouth thus becomes a mixture of pure and impure air. This 

 part of the process is termed expiration. When the floor of the 

 mouth rises again some of this mixed air is forced into the lungs, 

 the external nares being still closed. This constitutes the proc- 

 ess of inspiration. Finally the external nares are opened again, 

 and the fluctuating movements of bucco-pharyngeal respiration 

 are resumed. 



In addition to these two methods of aerial respiration the 

 lunged salamanders which have come under my observation pos- 

 sess, when in the water, an aquatic bucco-pharyngeal respiration. 



The Gages ('86^, '91) have reported such an aquatic respira- 

 tion for Diemyctylus as well as for some of the lower Urodcles. 

 Their statements are, however, indefinite as to the exact method 

 by which the water is alternately taken into and expelled from 

 the mouth. O. P. Hay ('89) seems to have made more exact 

 observations upon Amblystomas, of which he says that " streams 

 of water are drawn in through the nostrils and this water is then 

 expelled at intervals by the mouth." This is precisely the 

 method of bucco-pharyngeal respiration of water which I have 

 many times verified with a lens by the aid of solid particles (car- 

 mine or sediment) suspended in the water in which specimens of 

 Dicmyctylus and Amblystoma were submerged. The muscular 

 act seems to be exactly the same as in the bucco-pharyngeal 

 aerial respiration, but owing to the heavier fluid the act is a much 

 slower one, though varying in depth and rapidity with the activity 

 of the specimen, as the accompanying tabulation of observations 



