DIGESTIVE SYSTEM 



123 



semi-apes and apes, possess a so-called lower tongue, as a single 

 or double projection. This formation, which in the anthropoids 

 (with the exception of the chimpanzee) is but slightly developed, 

 in children and adult human subjects easily recognisable, and in 

 the negro variable, is, according to Gegenbauer, the rudiment 

 of a primitive tongue, but in the opinion of Oppel to be regarded 

 as a new character, in course of development. 



Common to all b 



the mammals, man 

 included, and oc- 

 curring also in the 

 amphibians is the 

 ramification of the 

 lingual muscles, re- 

 sulting in the firm 

 structure and great 

 mobility of the 

 tongue. Generally 

 speaking, in the 

 tongue of every 

 mammal we may 

 distinguish exter- 

 nal and internal 

 muscles, and, ac- 

 cording to their 

 direction, vertical, 

 transverse and lon- 

 gitudinal fasciculi. 



The internal 

 organ of support 

 for this structure 

 in man is the sep- 

 tum, consisting of 

 connective and adipose tissue, and elastic fibres ; its analogy 

 with the "lyssa" of certain mammals, with the lingual cartilage 

 of the lower vertebrates is proved by the fact that in the human 

 foetus of eight to nine months isolated portions of cartilage may 

 be observed in the septum. In addition to the above-mentioned 

 lyssa an adipose body contained within a fibrous membrane 



FIG. 67. Human tongue. (Thome, Zoologie.) a, 

 b, vocal cords; c, glottis; e, glossopharyngeal 

 nerve ; f, lingual ; g, branch of fifth cerebral 

 nerve ; h, circumvallate papillae ; i, fungiform 

 papilla; ; k, filiform papillae ; 1, thyro-glossal 

 duct area. 



