Summary. 



The author's morphological and experimental researches have given the 

 following results: 



1) The Organon vomer o-nasale or the Organ of Jacobson is an organ of smells- 

 it does not contain air, hovever, but only a serous glandular secret. 



2) This serous, glandular secret, which is sucked into the organ from the 

 cavities of the nose or the mouth, forms the medium, which conveys the olfactory 

 stimuli to the olfactory cells. 



3) The above-mentioned secret is produced by orbital glands, by great nasal 

 glands or by salivary glands. 



4) According to the position of the orifice of the organ, it takes the odorous 

 substances either from the cavity of the mouth or from that of the nose or 

 from both. 



5) The sucking in of the secret of the glandules is made by means of a 

 pumping mechanism in the wall of the organ. 



6) In the Mammals, the piston of this pumping mechanism consists of a 

 contractile cavernous body situated in the lateral wall of the organ inside its skeleton 

 capsule. 



7) In the Lepidosatiria, the piston is formed by a yielding part in the bottom 

 wall of the capsule of the organ (consisting of cartilage and bone or solely of 

 cartilage). When pressing the tongue or the object to be swallowed against the 

 roof of the mouth, the piston springs upwards and diminishes the cavity of the 

 o]'gan. But, as soon as the pressure ceases, the piston springs back and the cavity 

 of the organ widens again. 



8) In the majority of cases, the organ of Jacobson is to be considered as a 

 smell-organ of the mouth, i. e. as an organ of smell which controls the foodstuffs 

 taken into the cavity of the mouth. 



9) In many cases however, it may besides be regarded as a sensory organ 

 of scent, i. e. as an organ of smell, which is able to control even the smallest 

 odorous particles outside the animal. 



1 0) These odorous matters are carried to the orifices of the organs of Jacobson 

 either by the tongue (as in the Lepidosanria fissilinguia) or by the inhaled air and 

 the serous fluid from the cavity of the nose (as in the Mammals). 



