OBSERVATIONS ON THE RELATIONS OF THE ORGAN 

 OF JACOBSON IN THE HORSE. 



By R. Broom, M.D., B.Sc. 



(Plate i.) 



In Herzfield's recent paper " Ueber das Jacobson'sche Organ 

 des Menschen und der Saugethiere "* he calls attention to the 

 peculiarity in the Horse in that in it there is no naso-palatine 

 canal opening into the mouth, and that the duct of Jacobson, 

 instead of opening into the naso-palatine canal as in most higher 

 mammals, opens into a deep depression in the nasal floor. This 

 condition he found to exist in both the Horse and the Ass, and 

 he states that according to Gratioletf a similar condition is found 

 in the Camel and Giraffe. 



A8 I had from my studies on the organ of Jacobson in different 

 Orders come to the conclusion that though the degree of develop- 

 ment of the organ may vary greatly in different genera the type 

 on which it is formed is remarkably uniform in each Order, I 

 naturally became anxious to find the explanation of how it was 

 that the organ in the Horse differed apparently so rem.arkably 

 from the normal Ungulate type as found in the Sheep. 



Being fortunate in having in my possession the head of a foetal 

 Horse I have made a study of the relations of the organ by 

 means of a series of vertical sections. Though the examination 

 of a younger specimen would doubtless have been even more 



* ZoDlog. Jahrbuch, Abtheil. ftir Anatomie und Ontogenie. BJ. iii. 188). 

 t Recherches sur i'organe de Jacobson. aris, 1845. 



