165 



Fig. 1. 



Fig. 2. 



Fig. 3. 



Fig. 1. Coronal section showing the or^ m of Jacobson (J) in foetal Platypus. ^ 12. 

 N. nasal cavity ; Sd. Stenson's duct. 



Fig. 2. The epithelial structures from Jacobson's organ from the right side of 

 Fig. 1. Zeiss D. d. duct of Jacobson's organ; m. mesial wall; I. lateral wall. 



Fig. 3. Transverse section showing shape of Jacobson's organ in adult Platypus. 

 y^ 12. (. turbinate process; in. mesial wall. 



(Fig. 3 m) presents a structure closely resembling that described and 

 figured by Dr. Klein ^) in the corresponding part of the organ in the 

 dog. Its epithelium is more than twice as deep as the ciliated epi- 

 thelium, which covers the turbinate ridge (t), and which Symington 

 has described and figured. It appears to be destributed over a relati- 

 vely much wider area than in the dog and the neuro-epithelial cells are 

 very numerous. This is significant in view of the large mass of nerve 

 fibres proceeding from this region. As I had no intention of examining 

 the organ of Jacobson at the time fresh material was available, 

 no GoLGi-preparations were made; but the researches of von Brunn ^), 

 VON Lenhossek^) and Ramon y Cajal *) leave no doubt as to the 

 relations of neuro-epithelium and nerve fibres. The latter form a 

 very thick mass lying between the mesial wall of the organ and the 

 nasal septum, and separated from the epithelium by a thin layer of 



1) Quarterly Journal of Microscopical Science, 1882. 



2) Arch. f. mikr. Anat., Bd. 39. 



3) Anatomischer Anzeiger, 1892, No. 19 u. 20. 



4) Arch. f. Anat. und Physiologie, 1893, Heft 6. 



11 



