472 KANSAS CITY REVIEW OF SCIENCE. 



to which an animal belongs, they do also indicate the intelligence of the posses- 

 sor of them. Therefore, the point I shall make is this, that the nearer an ani- 

 mal's tooth approaches the typical human molar tooth, the nearer that animal's 

 brain approaches the human brain, both as to comparative weight and size, also 

 as to position, convolutions and depth of sulci. The brain or encephalon is di- 

 vided into four parts; the cerebrum, the cerebellum, the pons varolii, and the 

 medulla oblongata. For our purpose we shall use only the first two parts. The 

 brain structurally is divided into white and gray matter, the white making up the. 

 greater part of the whole, the gray being upon the surface and the sulci, and upon 

 its amount depends the power either intellectual or animal; the amount of gray being 

 augmented by the number of convolutions and the depth of sulci. The cerebrum 

 controls the intellectual or intelligent, and the cerebellum the animal functions of 

 the creature. In the human brain the cerebrum in amount is to the cerebellum, 

 as nine to one. In the human brain the cerebrum completely covers the cerebel- 

 lum when looking from the top of the head. The greater the size of the cerebrum 

 and cerebellum, the greater the number of convolutions and depth of sulci, the 

 'greater is the power of intelligence and animal functions respectively. Man, 

 from the nature of his construction, needs an intellectual brain, and that intellect- 

 ual brain needs a mixed diet upon which its integrity depends, and which it 

 cannot get with teeth like the shark, alligator, ox, or dog. Therefore, man has 

 teeth for a mixed diet because he needs them, and where there is no such diet 

 needed nature does not produce teeth like unto man's. Reasoning from this^ 

 basis, it is fair to presume that if there is a gradation of intellectual brain-power 

 from man down, there must also be gradations of teeth from man down. If we 

 look at the head of a wolf-fish we find the lowest order of brain-power, and a 

 very large number of pointed teeth, each tooth the same in shape but varying in 

 size, the same as regards the common pike. The character of its teeth would in- 

 dicate that its aim in life was to satisfy its hunger, which it does by tearing off 

 shell-fish from adjacent rocks with its front teeth and crushing them with its back 

 ones. The teeth are slightly anchylosed to the jaw as is the case with most fishes. 

 In the lizard (varanus Gouldii) we find that the teeth are produced like the alliga- 

 tors, but different in shape, being like flattened cones. They are all similar in 

 shape but different as regards size. The lizard has a very small brain, is very 

 stupid, slow of motion, and like all reptiles, is cold blooded, caused by having 

 but three cavities in the heart, one auricle and two ventricles, which causes the 

 venous and arterial blood to mix. When we come to examine the ophidian rep- 

 tiles (snakes) we find coldblooded reptiles, with a compUcated dental apparatus. 

 The teeth are different in size, same in shape. The venomous snakes have a 

 poisonous fang, but only one row of teeth in the upper and one row of teeth in 

 the lower jaw. The non-venomous snakes have two rows of teeth in the upper 

 jaw and one row in the lower, but no poisonous fang. They, like all reptiles, 

 have a quadrate bone. The teeth are organs of prehension, as snakes invariably 

 swallow their prey whole. When the viperine snake is about to strike the mouth 

 is opened, a muscle contracts and moves the quadrate bone forward; this move- 



