394 Jour)ial of Coiiiparafhe Neurology and Psychology. 



in the guinea pig, the cellular anlage of the olfactory nerve is made 

 up of cells arising both from the brain and epithelium of the olfactory 

 pit. The evidence, however, which he presents is not very conclu- 

 sive. Chiarugi found a iibrillar stage following a purely cellular 

 stage. He believes that more than one fiber may arise from one cell. 



His^ was the first to affirm that the olfactory nerve arises exclu- 

 sively from the periphery. Since his views have exerted such a great 

 influence upon those held at present concerning the origin of the olfac- 

 tory nerve, it will be well to examine his work in detail. 



He finds, first, in a four and one-half week old human embryo, a 

 mass of cells lying near the olfactory plate, which he calls a ganglion, 

 having apparently no connection with the brain. But even in earlier 

 stages he finds in the olfactory plate, as in the medullary plate of the 

 same period, two kinds of cells, one of which later becomes neuro- 

 blasts with fibrillar processes, while the other contributes to the forma- 

 tion of the supporting elements. His states that the cells which will 

 form the neuroblasts, wander out of the olfactory epithelium, to form 

 the ganglion. It is the processes of these cells which form the fibers 

 of the olfactory nerve. The cells are bipolar, one process passing to 

 the olfactory epithelium, the other passing toward the brain. Later 

 the cell bodies pass toward the bulbus and are found in the cap-like 

 covering of the bulbus. He believes that the nuclei lying in the 

 course of the adult nerve do not belong to the fibers, but to the cellu- 

 lar nerve sheath. 



Disse' applied Golgi's method to the study of the various stages 

 in the development of the olfactory nerve in the chick. He agrees 

 with His that the olfactory fibers arise from the neuroblasts that origi* 



^ W. His. Ueber die Entwickelung der Riechlappens and des Reichgang- 

 lions und iiber diejenige der verlangerten Marks, Verhandl. d. Anat. Ge- 

 seUschaft, 1889. 



Die Formentwickelung des menschlichen \'orderhirns, Abliandl. d. math- 

 phys. Klasse der Kgl. Sachs Gesellsch. d. IVissenschaften, Bd. X\', 1S90. 



^ DiSSE. Ueber die Erste Entwickelung des Riechnerven. Sitzungsberichte 

 der Gesellschaft zu Beforderung der gesamten Natiirwissenschaften in Marburg, 

 No. 7, October, 1896. 



Die Erste Entwickelung des Riechnerven, Anat. Hefte, i Abteilung, Heft 

 9, 1897. 



On the Early Development of the Olfactory Nerve. Proceedings of the 

 Anatomical Society of Great Britain and Ireland, published in the Journal of 

 Atiatomy and Physiology, 1 901. 



