268 CAUSES OF DEGENERATIVE EVOLUTION 



dence between atrophy and loss of function. The 

 second arch becomes connected with the third, the 

 parts of which are, in the adult, the styloid pro- 

 cess, the stylo-hyoidean ligament, and the lesser 

 horn of the hyoid bone. According to the weight 

 of the tongue, the parts of the second arch become 

 more or less developed. In man the suspensory 

 apparatus of the hyoid bone is extremely simple, 

 and it is still more reduced in birds. " The 

 tongue, reduced to a minute cartilage, no longer 

 requires the support of a bony base so that the 

 hyoidean apparatus might almost be removed from 

 the anatomy of a bird. It is present, but in a 

 rudimentary condition " (Geoffroy-Saint-Hilaire). 



In the horse, which has a heavy tongue, the 

 second arch is strong and completely bony. 



In fish the hyoidean system is still more im- 

 portant, although in them this is associated not 

 with any importance of the tongue, but with the 

 branchial apparatus. The parts of the second arch 

 are very strong, as they form a fulcrum against 

 which the branchial system works, but its main 

 parts are recognizable. " The hyoidean apparatus 

 is the same in all vertebrates ; its functions are at 

 a maximum in fish, and at a minimum in birds, 

 while in mammals the condition is intermediate " 

 (Geoffroy-Saint-Hilaire). 



II. TRANSFERENCE OF FUNCTION. Among plants 

 and animals there are many instances of organs well 

 developed in younger stages of life, but which 



