470 



glandular tubules near the end of the hypophysis into the central 

 cavity which here terminates among the tubules, as has been pre- 

 viously mentioned. From the sections it appears more probable that 

 the secretion finds a free outlet into the mouth cavity. 



Nachdruck verboten. 



The Connection l)etween the Olfactory Bulb and the 

 Hippocampus. 



By G. Elliot Smith, 



Demonstrator of Anatomy, University of Sydney, N, 8. W. 



With 2 Figures. 



It has long been known that the hippocampus is closely connected 

 in some way with the olfactory sense but what exactly that con- 

 nection is, by what paths the olfactory impulse reaches the hippo- 

 campal region, has, as far as I am aware, never been demonstrated. 

 ZucKERKANDL has showu ("Ueber d. Riechbündel des Cornu Ammonis", 

 Anatomischer Anzeiger III, 1888) that a direct nerve path connects 

 the two regions. Edinger ("Riechapparat und Ammonshorn", Anat. 

 Anzeiger VIII, 10. 11, quoted by Herrick — Journal of Comparative 

 Neurology. Vol. Ill) is reported to have traced the external olfactory 

 root into the hippocampus. 



In the Monotremata and Marsupialia, in the absence of a corpus 

 callosum, the hippocampus retains its true morphological position, as 

 the upper margin of the j^ssura choroidea in its whole extent, and ex- 

 tends forwards in exactly the same relative position as the Randbogen 

 (Schmidt) occupies in the foetus of the placental mammal. This is the 

 position occupied by the hippocampus in all the Submammalia — a 

 position from which it becomes deposed in Eutheria on the appearance 

 of a corpus callosum — a structure, which is probably characteristic 

 of the placental mammal. The close approximation of the anterior 

 extremity of the hippocampus to the olfactory lobe affords an 

 opportunity of establishing their mutual histological relations with 

 a clearness and certainty to which one cannot hope to attain 

 in the case of the placental mammal. In the course of a somewhat 

 extended investigation in the histology of the monotreme and mar- 

 supial cerebrum ^), both adult and foetal, the following facts were made 



1) The full results of this work will be shortly published in the 

 form of a comparative study of the brain of Ornithorhynchus. 



