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Ivar Broman 



the cavity of the mouth. This explains why in cattle even the most constant of the 

 great glands of the nose, Gl. nasalis lateralis Stenonis, atrophies already in the 

 embryo. 



23) In the Lepidosauria the lachrymal canal, respectively the excretory duct 

 of the orbital gland, opens into (or together with) the duct of the organ of Jacobson. 

 On account of this, the cavity of the organ (when at rest, relatively wide) at less 

 strong pumping probably is filled solely by an indifferent secret flowing down from 

 the orhit. Stronger pumping again, gives rise to the sucking in of secret with 

 odorous substances from the cavity of the mouth. ' 



24) In the Mammals, the cavity of the organ of Jacobson is relatively narrow. 

 The glands belonging to the organ itself soon washes it completely clear from the 

 odorous particles, which entered at the pumping. 



2Ö) On account of tins, 1 regard the organ of Jacobson as a precisive organ 

 of smell, which very probably continues to be irritable to minimum quantities of 

 odorous matters even after the Regio olfactoria (in consequence of permanent irritation 

 and thereby subsequent overfatigue) has ceased to be irritable for the same. 



26) As it here has been proved, that the organ of Jacobson is an organ of 

 smell fej7- fluids and as we know through the researches of Döllkens (1909) and 

 Johnston (1913), that it is innerved by the same sensory nerve (N. terminalis), 

 which innerves the organ of smell of the fishes, it may be easily supposed, that 

 the organ of Jacobson is nothing else than the old organ of smell of the aquatic 

 vertebrates. 



