The Lateral Nasal Glands of Amphiiima. 169 



elongated snout of Amphiuma. This adaptation, however, involv- 

 ing as it does the persistence of the introductory passage, possesses 

 the disadvantage of affording no protection against the entrance of 

 dirt into this portion of the nasal passage, while, on the other hand, 

 the very pressure incident to the act of burrowing tends to force the 

 dirt into these introductory passages. Moreover, this lengthened 

 passage gives an additional area exposed to the drying effects of air 

 as it passes in and out with the respiratory act when the animal 

 is out of water and is not actually burrowing. Here we have a 

 clue to the function of the lateral or external nasal gland. The single 

 orifice through which the gland discharges is located, as has been 

 said, upon the forward directed surface of the spiral fold. The 

 secretion is therefore, by the very conformation of the parts, directed 

 outward. Thus during the respiration of air, in the long journeys 

 which these animals are said to make under the loose leaves and 

 sticks covering the ground of the swamps which they inhabit, the 

 copious secretion must serve its primary function of keeping the 

 lining of the introductory passage from drying; and when the animal 

 is burrowing the secretion is undoubtedly used as a means for flush- 

 ing out the fine particles of dirt which tend to plug up the introduc- 

 tory passage ; but for some such device as this the dirt would, with 

 the reopening of the inner end of the introductory passage and the 

 resumption of respiration, be dra^vm into the nasal cavity and thus 

 defeat the purpose of the constrictor muscle. 



This latter function of the gland I was able to demonstrate experi- 

 mentally by first carefully drying with filter paper the whole external 

 nasal region of a living Amphiuma, and then filling the introductory 

 passages with dry dirt. After a few moments the dirt became very 

 moist and was soon forcibly expelled, leaving the passage quite clear 

 and clean. A forcible expiratory act seemed to assist the glands in 

 their final effort at expelling the obstruction. 



Thus we see both in the very strongly developed condition of the 

 constrictor and dilatator muscles and in the highly specialized state 

 of the external nasal glands of Amphiuma further adaptations to the 

 burrowing habit which in other respects has had such a decided effect 

 upon the form and structure of the animal. 



Smith College, Northampton, Mass., July 20, 1908. 



