off (probably as the result of several attempts at passing a probe 

 made in the dissecting room). 



Section II. Shows a duct of normal structure with ciliated epithe- 

 lial lining. Prior to removing the tissue to prepare it for micro- 

 scopic examination this portion of the duct had been incised longitudi- 

 nally with a sharp scalpel. The lumen is therefore incomplete. 



Section III. Shows fibrous tissue with several small arteries 

 and veins cut transversely. At places in the section there are small 

 masses of epithelium and a few gland alveoli cut transversely. The 

 tissue her is not in a perfect state of preservation. (The subject 

 had been in the Department for nearly six months before the nasal 

 duct was examined.) 



Section IV. Shows loose fibrous tissue with numerous mucous 

 and serous gland alveoli cut transversely. 



The microscopic evidence is therefore strongly indicative that the 

 abnormal opening of the duct was not the result of operative inter- 

 ference (Sections I and II). Section IV showed nothing more than 

 the normal structure of submucous tissue. It therefore definitely 

 negatived the possibility of there being even a microscopic duct in the 

 normal position. Section III was rather surprising. The existence 

 of gland alveoli at that level was unexpected. It was impossible to 

 trace their ducts as during the macroscopic dissection shreds of tissue 

 had been removed. The vascularity of the tissue was also unexpected. 



A search through the literature has failed to discover any record 

 of a similar abnormality. In view of the normal developmental history 

 of the duct this is not a little surprising. 



As is well known the nasal duct is formed by the canalization 

 of a solid epithelial column derived from a thickening of the deeper 

 layers of the epidermis, which occurs along the line of junction of the 

 maxillary and lateral nasal processes after the fissure between them 

 has been obliterated. As is also well known a lateral bud may arise 

 from this column and by its penetration of the mucous membrane of 

 the inferior meatus and by its subsequent canalization may cause the 

 not very infrequent abnormality of a nasal duct opening by two 

 orifices into the nasal cavity. Such is the normal condition in 

 the dog. 



The possible explanations of this rare if not unique abnormality 

 are 1) that a lateral bud was formed at a slightly higher level than 

 usual and that it perforated the wall of the nasal capsule instead of 



