50 DR. REUBEN T. HARVEY. 



Note on the Organ of Jacobson. By Reuben T. Harvey, 

 M.D., E.K.Q.C.P., Lecturer on Physiology in the Carmi- 

 chael Medical School, Dublin. 



During the spring of this year, when engaged in some work 

 on the histology of the nasal mucous membrane in the mouse, 

 my attention was directed by Dr. Klein^s paper in the January 

 number of this Journal to the organ of Jacobson. The dis- 

 tinctly olfactory character of the epithelium in this organ induced 

 me to seek for the junction which was supposed to exist between 

 it and the mouth, with a view of determining how the transition 

 in the character of the epithelium took place, or of discovering 

 some vestige of the connection which exists in the early foetal 

 condition between these tubes and the nasal cavity. With the 

 the material which I then had at my disposal, I failed to discover 

 any communication between the organ of Jacobson and the 

 mouth ; and my sections left no doubt on my mind but that the 

 opening from it was into the nostril, although they did not 

 demonstrate the exact manner in which such opening took place. 



Por want of time and suitable material I was obliged to post- 

 pone my investigations until the conclusion of the winter 

 session. On resuming, I had no difficulty in obtaining a series 

 of vertical sections from before backwards of a mouse^s head, 

 which demonstrated the opening sought for. Pour days after 

 this I received the April number of the Journal containing Dr. 

 Klein^s second paper, in which he records a similar discovery in 

 the guinea-pig. I have since worked out the point in the kitten 

 and hedgehog, and I desire now briefly to describe some of the 

 more important facts in each case. 



I. The Mouse. — The manner in which Jacobson's organ is 

 connected with the nostril in the mouse is very similar to what 

 Klein describes in the guinea-pig. In successive sections from 

 before backwards the following stages may be observed : — Pirst, 

 the mucous membrane lining the chink, into which the floor of 

 the nostril is narrowed in front, is composed of a stratified scaly 

 epithelium, which stains much more intensely than the rest of the 

 nasal epithelium. Secondly, the inferior margin of this chink 

 bends inwards and upwards into the septum under a small 

 isolated mass of so-called cellular cartilage. Thirdly, as this 

 depression into the septum deepens it becomes somewhat flask- 

 shaped, its orifice becoming elongated and narrowed. Ulti- 

 mately the neck becomes obliterated, and we have then to deal 

 with the section of a complete tube. Lastly, the layer of scaly 

 epithelium is replaced by columnar, and the inner surface of the 



