Bedford, Olfacto7y Nej^ve in Szvine. 393 



A. VON Kolliker' is another able investigator who claimed a cen- 

 tral origin for the olfactory nerve. His observations were made upon 

 mammals. 



In 1890, however, he completely changed front and claimed a 

 peripheral origin for the nerve in both the chick and mammals. In 

 mammals he found (in the material at his disposal) the olfactory nerve 

 always firmly attached to the epithelium of the olfactory pit. He 

 found, however, no stage in which the olfactory nerve was connected 

 with the olfactory pit without also being connected with the brain wall, 

 yet he considers it evident that the olfactory nerve arises in the olfac- 

 tory epithelium and grow.s toward the brain. KHllijcek believes 

 that the nuclei in the adult nerve belong to the nerve fibers themselves 

 and that each fiber contains several nuclei. "Each fiber corresponds 

 to a complex of nerve cells." The presence of mitoses within the an- 

 lage is regarded as evidence that the cells lengthen and form fine 

 fibers, while the nuclei divide several times. 



Beard, ^ in his System of Branchial Sense Organs and their As- 

 sociated Ganglia in Ichthyopsida, gives still another explanation of the 

 origin of the olfactory nerve. He claims that the anlage of that nerve 

 is made up of cells arising from both the brain and the nasal epithe- 

 lium. A cell-mass grows from the forebrain, cells from the epithelium 

 become connected with this and thus the ganglion is fully formed. 

 Beard's observations were made upon the Torpedo. His general 

 scheme of nerves is based upon conditions found in some of the more 

 posterior nerves. He has found that in the selachians, the nerves that 

 supply the gill arches are formed through the union of the two anlages, 

 one arising from the brain and one arising as a thickening of the over- 

 lying region of the integument. Beard, in support of his view, at- 

 tempts to homologize the nasal epithelium with a branchial sense 

 organ . 



Chiarugi^ agrees very closely with Beard. He concludes that, 



' A. VON KoLLiKER. Entwickelungsgeschichte, 1879. 



Ueber die erste Entwickelung der Nervi olfactorii, Verhandl. d. physikalisch 

 med. Ges. »u IVilrztiurg, Sitz. von 6 Juli, 1890. 



' J. Beard. The System of Branchial Sense Organs and their Associated 

 Ganglia in Ichthyopsida, Quart. Joum. Micros. Sc, Nov., iSS^. 



^ Chi.\rugi. Observations sur les premieres phases du developpement des 

 nerfs encephaliques chez les mammiferes, et, en particulier, sur la formation du 

 nerf olfactif, Archiv. Italiennes de Biologie, XV, 1891. 



