204 





olo 



Fig. 3. LoDg. sec. through 01. O. of an emb. of Torpedo ocellata. Stage .7".-^. 250|1. 



of separation of the brain from the organ some of the connecting cells 

 elongate, send out fibres, and thus form a beginning of an olfactory 

 nerve or ganglion, so that a kind of connection always exists from 

 the very first. 



A similar mode of development of the olfactory nerve or ganglion 

 has, as far as I know, not been described before. 



In the more developed organs there are the olfactory cells proper, 

 which send their nerve-fibres into the ganglion, but these cells are 

 first seen in a much later stage, corresponding to or P of Balfour 

 and according to S. R. Cajal (5) terminate in a ramification which 

 surrounds and intersects the cells of the ganglion and their processes. 



The next stage which I have been able to obtain is much more 

 developed than the last and corresponds to M of Balfour. 



The olfactory organ is involuted and forms a pit or sack and is 

 situated below the olfactory lobe (Fig. 4). The formation of the bulbus 



