SEA-FISHERIES LABORATORY. 259 



The right Bulbus olfactoriust lies mostly under the 

 corpus striatum (the latter is the cerebral hemisphere of 

 older authors). Behind, it is free, unconnected with the 

 striatum and ends bluntly, but in front it acquires a firm 

 connection with the striatum. Anterior to this again it 

 separates once more from the striatum. So far it has been 

 increasing in size, but it now begins to taper down, its 

 ventral portion becomes fibrous, and its dorsal divided 

 into two. The upper or cerebral portion disappears in 

 front, and the remainder narrows down into the cylindrical 

 nervus olfactorius. Both olfactory nerves lie to the right 

 of the upper or left optic nerve. As the nerve passes 

 forwards it becomes divided by connective tissue strands 

 into two or more fasciculi, each of these again being 

 further subdivided into small bundles of fibres. The 

 right olfactory passes through the foramen olfactorium in 

 the right prefrontal, turns up at once and breaks up in 

 the olfactory laminae of the right nasal chamber. 



The left Bulbus olfactorius is not free behind like the 

 right, but passes imperceptibly into its striatum. Nor is 

 it situated below the latter, but between the two striata 

 (see fig. 28). The appearance therefore of this portion of 

 the brain is very asymmetrical, and suggests a rotation 

 towards the right side of the ventral axis of the brain 

 only. The left bulbus is perceptibly smaller than the 

 right, but the left striatum extends further forwards than 

 its fellow. The bulbus separates from the striatum in 

 front, becomes fibrous at its right ventral corner and gives 

 off the left olfactory nerve, which passes at once to the 

 right side, so as to lie near the right bulbus. The left 



+ This structure is also called by some authors the Tuberculin;/ 

 olfactorium (Stannius) and Lobus olfactorius. We have no space to discuss 

 the precise significance of each of these three terms, if indeed they have 

 any (but see Elliot Smith, Jour. Anat. and Phys., xxxv., 1901). 



