OF DENISON UNIVERSITY. g| 



The superficial tract of the olfactory fibres passes along the vcn 

 tral surface in ill-defined bundles to the hippocampal region. Here 

 small, dark, angular, multipolar cells abound, similar to those of the 

 anterior or fornix eminentia of the thalamus. The relation oi the 

 hippocampus with the fornix has already been indicated. It is prol)a- 

 ble that fibres from the hippocampus pass to the higher cortical regions 

 via the fornix commissure, just as in the reptilia. It is not impossible 

 that there is a connection of the central tract with the hipjKxampus, 

 but such a communication was not demonstrated. 



Other fibres seem to depart from the main tracts and gather at the 

 anterior commissure. The anterior'commissure in the brain of the rat 

 was studied for comparison with the result of confirming the suggest- 

 ions already made. 



The transverse sections have thrown no light on the course of the 

 fibres from the dorsal nucleus of the thalamus {taena thalami), which 

 in horizontal sections are found to pass ventrad along the cephalic bor- 

 der of the thalamus, behmd the callosum and anterior commissure, to 

 the point of entrance of the pyramidal fibres into the hemisphere. 

 We think it probable that these fibres make their way to the hipjx)- 

 campal or occipital region of the cortex. 



The Prosencephalon. 



(It will be convenient in presenting the few notes we at present 

 offer upon the fore-brain, to reverse the order hitherto followed.) 



{a.) The olfactory lobes are of considerable size and are connect- 

 ed with the cerebral hemispheres by a relatively thick crus olfactorius. 

 The form of the bulb proper is ovoid and it is oblicpiely a|)|)ressed 

 upon the front of the hemisphere. 



Microscopically the structure is not unlike that of the human sul>- 

 ject. The outermost layer consists of bundles of olfactory nerves 

 passing in various directions to unite with the glomerular layer. The 

 exact method of emergence was not observed. The so-calleil glom- 

 erular layer is simply a belt of fibre bundles, each bundle being sur- 

 rounded by a cluster of " neurilema nuclei." 'i'he olfai tory fibres are 

 more or less convoluted and are sei)aiatc(l by a dense reticulum of 

 neuroglia. The glomerular layer insensibly passes into the more hom- 

 ogeneous but otherwise similar gelatinous layer. Here the olfactory 

 fibres pass through a dense net-work of connective tissue with sparse 

 neuroglia nuclei. Forming the inner boundary of the gelatinous layer 



