THE ORGAN OF TASTE 



chouc) , through which air is drawn into the nostril. A nonodorous tube can be 

 introduced into this, so that any desired length of the odorous surface may be 

 covered. The intensity of the smell is proportional to the length of the cylinder 

 used. 



The galvanic current one electrode being placed in or on the nose, the other 

 (indifferent) being held in the hand upon kathodal closure and persistence of the 

 current, likewise upon anodal opening, excites a sensation of smell that Kiesel- 

 bach compares to the smell produced upon striking flint. Induced currents have 

 no effect. 



Comparative. In the lowest vertebrates the olfactory apparatus is represented 

 by depressions to which the olfactory nerve passes. Amphioxus and the cyclo- 

 stomes have only one olfactory depression, while all other vertebrates have two. 

 In many selacians the olfactory depression communicates with the mouth by 

 means of a canal. In frogs the olfactory organs open into the mouth through short 

 passages. In the higher vertebrates the nose develops together with the palate, 

 and becomes more and more independent. In the gymnophions, a group of 

 amphibians, the olfactory apparatus is extraordinarily developed from the presence 

 of four nerves, while, on the other hand, the ears and eyes are stunted. The 

 cetaceans have no olfactory nerve. In many mammals there is in the anterior 

 part of the septum a hollow cavity, lined with cells similar to the olfactory cells, 

 opening either into the nasal cavity or into the canalis incisivus, and to which a 

 branch of the olfactory nerve runs; it is known as Jacobson's organ, and is un- 

 developed in man. Cephalopods have olfactory depressions, lined with ciliated 

 olfactory cells, back of the eyes; the olfactory nerve arises near the optic nerve. 

 In molluscs also, there are ciliated places that are considered olfactory organs. 

 In arthropods the olfactory organs lie in the feelers and antennas, in the first as 

 cilia in connection with a ganglion and nerve. In crabs they are situated in the 

 outer arms of the antennula. Ciliated, shallow or flask-shaped depressions 

 supplied with nerves represent the olfactory apparatus in the higher worms. 

 All other animals appear to possess no especial organ. 



Historical. Theophrastus (born 311 B. C.) mentions the short nose of man; 

 that animals enjoy their food only from its odor; that strong perfumes cause 

 headache; that many fragrant salves impart an odor to the urine; that there 

 are many connections between smell and taste. Rufus Ephesius described the 

 passage of the olfactory nerves through the cribriform plate of the ethmoid (97 

 A.D.). According to Galen the sense of smell has its seat in the cerebral ven- 

 tricles. The monk Theophilus Protospatharius (end of the eighth century) de- 

 scribed the olfactory nerve as the nerve of smell. Rudius (1600) dissected a man 

 with congenital anosmia, in whom the olfactory nerves were absent. Sommering 

 wrote a masterly description of the olfactory apparatus, Cloquet (1815) of its 

 physiological and pathological phenomena. 



THE ORGAN OF TASTE. 



SITUATION AND STRUCTURE OF THE ORGANS OF TASTE. 



There are still many contradictory views as to the extent of the region 

 in which the sensation of taste is developed, and accordingly as to 

 whether the various nerves in question are to be considered as possessing 

 taste-fibers or not. (i) The root of the tongue in the region of the 

 circumvallate papillae, the area of distribution of the glossopharyngeal 

 nerve, is undoubtedly endowed with taste. (2) So also is the tip of the 

 tongue and its margins, through the intermediation of most of the 

 fungiform papillae (the filiform papillae and about 20 per cent, of the 

 fungiform papillae are insensitive to taste), but with many individual vari- 

 ations; so that often not all varieties of taste are appreciated. The 

 relations of the nerves to these situations are pointed out in the descrip- 

 tions of the lingual nerve and the chorda tympani. (3) The lateral 

 portion of the soft palate, its posterior surface, the glossopalatine arch, 

 the inner surface of the epiglottis are endowed with taste through 



