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hidden by a series of rope-like strands (tractus bulbo-tuberc.) springing 

 from its dorsolateral margin and winding around its surface to reach 

 the tuberculum olfactorium where the fibres spread out and end. There 

 could be no doubt, even on mere macroscopic examination, that these 

 strands represented a direct tract from the olfactory bulb to the olfactory 

 tubercle. In GoLGi-preparations of Cavia (five days old) these fibres 

 can be seen ending among the cells in the tuberculum. 



In confirmation of this interpretation there is the evidence afiorded 

 by degeneration experiments. In the year 1894, while working in the 

 laboratories of Professor J. T. Wilson in the University of Sydney, 



Lobus pyriformis — -\ 



Tractus olfact. 



Tuberculum olfactorium 



Fig. 2. A coronal section through the cerebrum of Perameles nasuta showing 

 the distribution of the fibres degenerated after an injury to the left bulbus olfactorius. 



I extirpated the anterior extremity of the left olfactory bulb in Perameles 

 and obtained by the MARCHi-method the result shown in the accom- 

 panying diagram (Fig. 2). Degenerated nerve-fibres are found scattered 

 throughout not only the tractus olfactorius and its prolongation over 

 the whole surface of the lobus pyriformis, but also over the lateral 

 half of the tuberculum olfactorium. As no degenerated fibres occur 

 in the commissura ventralis in this case it is clear that the formatio 

 bulbaris only was damaged, and hence we can look upon the blackened 

 fibres on the surface of the tuberculum olfactorium as the uninterrupted 

 prolongations of the axis- cylinders of the mitral cells — as a true tractus 

 bulbaris ad tuberculum. 



Not only is the tuberculum olfactorium directly linked to the ol- 

 factory bulb by this nerve tract, but it is also closely connected with 



