MAN AND APE COMPARED 9 



the foramen or hole in the base of the skull through 

 which the spinal cord passes is adjusted closer and 

 closer to the centre of the base of the skull as the 

 spine becomes erect. In man, whose spinal column 

 is erect, the hole is in the centre of the base ; in the 

 reptile, whose spine is horizontal, the hole is at the 

 extreme end of the base. In the ape the spinal axis 

 is at an angle with the vertical line, and the plane of 

 the face conforms to a similar one. In keeping with 

 this law it will be seen in all animals that just in the 

 same degree as the angles widen, the foramen is 

 removed from the centre of the base towards the 

 occiput. 



It may be noted here, however, that the facial 

 angle is never exactly the same as the spinal angle. 

 The facial plane of the reptile is not quite horizontal, 

 nor that of man quite vertical, but the ratios of 

 angularity are constant. Even the habit of rearing 

 modifies to some extent this character, but it is only 

 the normal pose of the animal that determines the 

 exact limit of it. 



In keeping with these facts it will be observed 

 that as the angle between the chin and the spine 

 widens, the lower jaws project, and the chin recedes 

 or flattens, and in a like degree the voice is modified. 

 The chin of man forms a right angle, but in the 

 reptile it is quite lost. In the former the vocal 

 powers are superior to that of all other animals, but 

 as we descend the scale they are reduced in scope 

 and degraded in quality, until in the lowest reptiles 

 they become a mere hiss or squeak. 



