MINUTE ANATOMY OF ORGAN OF JACOBSON IN GUINEA-PIG, 219 
A FurtHer Conrrisution fo the Minute Anatomy of the 
Orean of Jacosson in the Guinea-vic. By E. Kuein, 
M.D., F.R.S., Lecturer on Histology and Embryology 
in the Medical School of St. Bartholomew’s Hospital. 
(With Plates XVI, XVII.) 
In my last paper on this subject (this Journal, January, 
1881), I have given a detailed description of the relations 
and minute structure of the Organ of Jacobson in the 
Guinea-pig. This description, although referring to the 
greater part of the Jacobson’s tubes, did not embrace the 
relations and structure of the anterior and posterior extre- 
mity of these organs. Extended observations have placed me 
in the position to give now a detailed account also of these 
parts in the adult guinea-pig. 
Jacobson, Gratiolet, Balogh, Fleischer and others, descrihe 
the organ of Jacobson of mammals as opening into the 
ductus Stenonianus, and in my first paper on this subject 
(this Journal, January, 1881) I had also accepted this view 
for the guinea-pig; but on more careful examination, with 
a view to definitely ascertain whether this be the case, 
I made the unexpected observation that the tubes (organs) 
of Jacobson do not open into the Stenonian ducts but stand 
in a free and open communication with the anterior part of 
the nasal cavity, or more correctly speaking, with the lower 
nasal furrow, that is, the furrow along the bottom of the 
nasal septum. As is well known the organs of Jacobson 
develop as diverticula of the front part of the primary nasal 
pits. Later on, in the mammal, they are placed in commu- 
nication with the Stenonian canals, while their communica- 
tion with the nasal cavity is lost. But in the adult guinea- 
pig there is no such relation, since the communication with 
the nasal cavity persists, and this opening of the tubes of 
Jacobson into the latter will be spoken of below as the 
mouth of the organ of Jacobson. That this persistence of 
an open communication of the Jacobson’s organs with the 
nasal cavity is of great importance I need hardly say, and 
I would only remind the reader that it is exactly the assumed 
non-existence of such acommunication with the nasal cavity, 
which made it very difficult to ascribe to these organs in the 
mammal a satisfactory function in conformity with their 
rich supply with olfactory nerve branches and with the pre- 
sence of their sensory epithelium. This communication 
