414 DB. R. BROOM ON THE 



On the Organ o£ Jacobson in SpJienodon. By 3?. Broom, M.D., 

 D.Sc, C.M.Z.S., Victoria College, Stelleubosch. (Com- 

 mmiicated by Prof. A. Dendt, D.Sc, P.L.S.) 



[Eead 21st December, 1905.] 



(Plates 41 & 42.) 



Thotjgh something is known of the Organ ot Jacobson in 

 Lizards and Snakes, principally through the researches of 

 Kitchen Parker (1), Born (2), and Seydel (3), scarcely anything 

 has been published, so far as I am aware, concerning the organ 

 in Bphenodon. Osawa (4) figures a transverse section showing 

 the relations of the organ in the adult animal, and the mode of 

 its opening into the choane, and he correctly states ; — " Eiue 

 pnpillenartige knorpelige Einragung in das Organ wie bei der 

 Lacerta kommt bei der Hatteria nicht vor." The bone which lies 

 above the organ he incorrectly calls the " turbiuale." This bone 

 has since been shown by Howes and Swinnerton (5) to be the 

 " septo-maxillary." In their paper on the development of the 

 skeleton in SpJienodon they figure a section through Jacobson's 

 organ shownng the relations of the organ to the cartilages and 

 bones, and state that whereas in Sphenodon " Jacobson's organ 

 is completely roofed in cartilage, in the lizard, according to 

 Parker, the septo-maxillary fulfils that f unci ion." Seydel (3), in 

 his recent work on the organ of Jacobson in Echidna, refers to 

 the condition in Sphenodon, and though he has evidently only 

 superficially examined the organ, he has made the following highly 

 important observations: — "Das Jacobson'sche Organ von Hat- 

 teria ist schlauchformig und ist dem unteren Eande des Septums 

 eingelagert. Seine Oeftnung liegt in der Niihe des vorderen 

 Eandes der Apertura interna ; nach hinten endet der Schlauch 

 blind. Das Organ erinnert also in Perm und Lage an das der 

 Mammalier ; ob sich die Aehnlichkeit audi auf don innereu Bau 

 erstreckt, weiss ich nicht. Jedenfalls ist die Thatsaclie bedeut- 

 ungsvoU, dass bei einem recenten Eeptil bei verhiiltnissmassig 

 primitivem Zustande des Grauniens ein den Maminaliern iihn- 

 Hches Jacobson'sches Organ besteht." 



Through the kindness of my friend Prof. Dendy, who has very 

 generously allowed me to freely examine his beautiful sections 

 of SjjJienodon embryos, I am fortunately in a position to give a 



