THE DOG. 87 



CHAPTER VIII. 

 The Dog. 



EVERY one is familiar with the great variety in size, 

 proportion, fur, and color presented by the different 

 races of dogs. 



We will not consider the external characteristics, but 

 will study in the dog the structure of the different regions 

 of the body, and compare this structure with that of the 

 corresponding parts of our own organism, noting the 

 resemblances and the differences. 



In examining the opened trunk we would find at once 

 that the large cavity extending from the base of the 

 neck to the origin of the posterior limbs is divided, as it 

 is in ourselves, into two parts, separated by a muscular 

 partition or diaphragm. 



In the thoracic cavity, bounded by the ribs, we would 

 find the same organs that we know, the heart, lungs, 

 and oesophagus. In the abdominal cavity are likewise 

 lodged the stomach, intestines, liver, spleen, kidneys, etc. 



There is nothing specially noteworthy about these 

 organs, excepting a greater development of the caecum, 

 which is that portion of the large intestine into which 

 the small intestine empties. 



The circulatory apparatus, respiratory apparatus, and 

 digestive apparatus are constructed according to the 

 same type that we have found in man. However, in the 

 digestive apparatus we will detect an important differ- 

 ence in the number, form, and arrangement of the teeth. 

 In front the jaws carry twelve incisors, six above and 



