128 SMELL, TASTE, ALLIED SENSES 



does this return till the buds regenerate. Since the taste- 

 buds disintegrate with the loss of the nerve and new ones 

 form only with the regeneration of this structure, it is 

 clear that the bud is dependent upon the nerve. As 

 Olmsted has suggested, it is probable that when a twig of 

 the nerve reaches a given spot in the epidermis, it gives 

 out a substance, hormone-like in character, that excites 

 the epithelial cells of that spot to form a bud much as the 

 embryonic eye cup of the vertebrate excites in the super- 

 imposed ectoderm the formation of a lens. In this way at 

 least the intimate dependence of the taste-bud on the re- 

 generating nerve-fiber can be explained and,, judging 

 from the account given by Landacre (1907) of the ontoge- 

 ny of these organs, a similar explanation may also 

 apply in development. 



9. BIBLIOGRAPHY. 



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Sauger. Arch. mik. Anat., Bd. 41, pp. 195-218. 

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Durchschneidung der zugehorigen Nerven. Arch. path. Anat. Physiol., 



Tel. Mod., Bd. 137, pp. 389-404. 

 CUSHING, H. 1903. The Taste Fibers and their Independence of the N. 



trigeminus. Johns Hopkins Hosp. Bull., vol. 14, pp. 71-78. 

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pen der Ganoideen. Arch. mik. Anat., Bd. 49, pp. 769-790. 

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muqueuse et dans les glandes sereuses de la langue dee mammiferes. 



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