THE ORGAN OF TASTE. 



1433 



which family and racial characteristics are often so strikingly reproduced. From the 

 second until the sixth month the nostrils are secluded by epithelial plugs which 

 subsequently undergo gradual resolution, so that before birth the nasal apertures are 

 unobstructed. The cartilages of the outer nose are derived from the common carti- 

 laginous capsule that constitutes the primary nasal skeleton. Subdivision into the 

 individual plates is probably effected by ingrowth of the surrounding connective 

 tissue (Mihalkovics, Kallius). 



THE ORGAN OF TASTE. 



In the description of the tongue and its papillae (page 1575), reference is made 

 to the presence of specialized epithelial structures, the taste-buds, that serve for the 

 reception of gustatory stimuli. These bodies collectively constitute the peripheral 

 sense-organ of taste and as such will be here considered. 



As implied by their name, the taste-buds (calyculi gustatorii) are irregular ellip- 

 soidal or conical bodies, sometimes broadly oval but more often slender in outline, 

 and in the adult measure from .070-. 080 mm. in length and about half as much or 



Fig. I 193. 



Lymphoid nodules 

 Foramen caecum 



Circumvallate 

 papillae 



Anterior palatine 

 arch 



Folia linguae 



Fungiform papilla 



Part 01 dorsum of tongue, showing papillae. 



less in breadth. Since they lie entirely within the epithelium clothing the mucous 

 membrane, the necessary access to the interior of the buds is afforded by minute 

 pore-canals, each of which, beginning on the free surface at the outer taste-pore, leads 

 through the intervening layer of epithelium to the inner pore that caps the subjacent 

 pole of the bud. By means of these canals the sapid substances dissolved in the 

 fluids of the mouth reach and impress the gustatory cells within the taste-buds. 

 Pore-canals are not, however, invariably present, since, as pointed out by Graberg, 

 certain taste-buds remain immature and retain their embryonal form and relations, 

 being broad and conical and in contact with the free surface. In such buds the 

 gustatory cells are few, only two or three, and so superficially placed that a dis- 

 tinct canal is absent. Occasionally double buds are encountered in which two 

 gustatory bodies are implanted by a common base, but partly retain their inde- 

 pendence in having separate distal poles, each provided with its separate taste-pore 

 and canal. 



The chief position of the taste-buds is within the epithelium lining the sides of 

 the annular groove on the circumvallate papillae, the buds being more numerous and 

 closely placed on the median than on the lateral wall of the furrow. Their number 



