NASO-LABIAL GROOVE OF LUNGLESS SALAMANDERS. 19 



groove may be seen, by the aid of a lens, to be absolutely free 

 from water which, moreover, recedes slightly from tJie border of 

 botJi naris and groove. Although the general mechanical process 

 by which the naris is thus quickly freed from water is obviously 

 through the medium of the groove, the absolute determination, 

 experimentally, of the physical principles involved in the perfor- 

 mance of the function of the groove and glands proved somewhat 

 difficult. The chief obstacles lie in the fact that the parts con- 

 cerned are so extremely small that the experiments must be made 

 under a lens of considerable magnifying power ; while the animals 

 themselves, which, of course, must be in their normal, active con- 

 dition, are extremely agile and object strenuously to the experi- 

 menting process. The most effective device was found to be that 

 of holding the specimen wrapped in a slightly moistened hand- 

 kerchief with only the head protruding. Specimens handled in' 

 this way, however, soon become too much dried to react normally 

 and must frequently be returned to the terrarium and a fresh 

 specimen taken. Although many experiments were made, with 

 varying degrees of success, the following set of experiments pre- 

 sents all of the facts from which the final conclusions were drawn. 

 These experiments or slight variations of them were repeated 

 many times and with different individuals, always with virtually 

 the same results. 



Experiment i . The head of the specimen was thoroughly 

 dried by means of absorbent paper. The nares were open and nor- 

 mal aerial respiration was taking place. A small glass tube, one 

 end of which was drawn out to a fine capillary point, was partly 

 filled with water. By blowing into the larger end of the tube a 

 tiny drop could be forced out through the capillary end. This 

 drop was deposited on one of the nares, the object being to get 

 a drop small enough to exactly fill the nasal depression. The 

 result was the immediate closure of the naris and a subsequent 

 immediate reopening, since the water disappeared at once. The 

 experiment was repeated with a drop of diluted India ink substi- 

 tuted for the water. At once the groove became filled with the 

 ink, which accumulated in a little drop at' the labial end where it 

 flowed off over the surface of the skin. The naris again reopened 

 immediately, completely free from the fluid. The mouth was 



