LECTURE VI. 157 



but in mere proportions in the degree of mobility, and in the 

 secondary arrangement of its parts." 



Fig. 57. Foot of Gorilla, after Huxley. 



Still, we must bear in mind that the ideas ''hand" and 

 " foot" may be very differently conceived, and that they run 

 into each other. Whilst most anatomists consider the essen- 

 tial part of the idea " hand" to be the opposability of the 

 thumb, I. Geoffrey St. Hilaire justly observes, that many 

 species of apes of the Old and New World, as the colohiis and 

 ateles, have no thumb at all, or only a rudimentary one in the 

 anterior limbs, and that the opposable thumb is in apes always 

 more developed in the hind limb than in the anterior one, 

 whilst the reverse is the case in man. Whilst, therefore, 

 Huxley restricts the notion hand so much, that he terms the 

 posterior extremity of the gorilla a prehensile foot, Geoffrey 

 St. Hilaire calls, on the contrary, every extremity a hand, 

 though it be thumbless, provided it has long and flexible 

 fingers, capable of prehension. According to this definition, 

 most birds, especially parrots, also possess hands. 



We now proceed to some internal organs, and especially to 



