The Lateral Nasal Glands of Amphiuma. 



145 



region where the dnct of the lateral gland oj^ens into it, however, the 

 nasal passage makes an abrupt twist, so that the longer diameter of 

 the lumen takes a vertical position (cf. Figs. 1 and 2). A short 

 distance posterior to this point the olfactory epithelium begins, the 

 portion of the passage anterior to this point serves, then, as an intro- 

 ductory passage comparable to that described by Bruner '01, and 

 Seydel '95, in larvaB of various urodeles (e. g., Triton and Ambly- 

 stoma), by Wilder 'Ola, in Siren, and by Hinsberg '01, in larval anu- 

 rans and in urodeles. 



V 



Fig. 2. — Transverse section somewliat posterior to Fig. 1. x 1^ 2/3. Ab- 

 breviations : ad, atrophied duct ; ci, cross section of the constrictor muscle 

 near its insertion ; co, cross section of the constrictor muscle near its origin ; 

 cdl, cross section of the dilatator muscle ; d, duct of the lateral nasal gland ; 

 Ic, longitudinal section through the body of the constrictor muscle ; Ig, lateral 

 gland ; na, nasal capsule ; ne, nasal epithelium ; n, nerves ; P, portion of the 

 premaxillary bone ; v, blood vessels. 



The twisting of the nasal passage in its transition from intro- 

 ductory to olfactory regions involves a thickening in the wall of the 

 passage. This thickening begins anteriorly in the mesial wall and, 

 gradually increasing, extends spirally around the cavity, ending in 

 the lateral wall. It results in the occurrence upon the inner surface 

 of the cavity of a spiral fold or ridge following the course of the 

 thickening. Upon the forward directed surface of this fold the duct 

 of the lateral gland opens. Thus by the very conformation of the 

 nasal passage the secretion of the gland is directed outward. 



