34 SMELL, TASTE, ALLIED SENSES 



6. Sense Buds. In 1884 Blaue described what he be- 

 lieved to be sense buds in the olfactory epithelium of 

 certain fishes and amphibians. This observation was not 

 confirmed by later workers and it appears, as Betzius 

 (1892b) has remarked, that the so-called sense buds are 

 not true buds but folds or bands of olfactory epithelium 

 seen in transverse section. The buds subsequently de- 

 scribed by Disse (1896b) in the nose of the calf and shown 

 by him to be supplied by free-nerve terminations are be- 

 lieved by this author to be concerned with taste rather 

 than with smell. These structures, however, are claimed 

 by Kamon (1904) not to be true buds but bud-like 

 appearances produced by the mouths of the Bowman 

 glands. If this is so, no sense buds of any kind are 

 known in the olfactory epithelium of vertebrates. 



7. Free-nerve Endings. In 1889 Grassi and Castronovo 

 with some uncertainty described from the epithelium 

 of the intermediate zone of the dog what they regarded as 

 free-nerve endings. Whether these were end-organs of 

 the olfactory nerve-fibers or not, they were unable to 

 determine. In 1892 similar endings were observed by von 

 Brunn at the border of the respiratory region in man. 

 Von Brunn believed these endings to be terminals of the 

 trigeminal nerve and, apparently by mistake, mentioned 

 Ramon y Cajal as their discoverer. Free-nerve endings 

 in the olfactory region were subsequently recorded by 

 Retzius (1892b) in the mouse and frog, by von Lenhossek 

 (1892) in the rabbit, by Morrill (1898) in Mustelus, by 

 Jagodowski (1901) in Esox, by Kallius (1905) in the 

 calf, and by Read (1908) in the kitten. Morrill 's obser- 

 vation for Mustelus has recently been confirmed by Asai 

 (1913). Hence there seems to be no doubt that in addition 



