CHAPTER IV 



BIRDS 

 THE PIGEON 



The domestic pigeon is one of the best birds for dissection be- 

 cause of its convenient size and the ease with which it can usually 

 be obtained. All birds are, however, essentially alike in structure, 

 and these directions may be used with the chicken, the sparrow, or 

 any other common bird. 



Two specimens will be needed for a complete dissection, one 

 for the study of the outer form and the viscera and one for the 

 muscles and the skeleton. They should be killed as needed, by 

 being placed in a closed jar with a little chloroform or ether, and 

 during the dissection should be kept in a i per cent solution of 

 formalin or in cold storage. Care should always be taken that 

 the specimens be covered by the preserving fluid, otherwise they 

 will mold ; the fluid should also be changed as often as it becomes 

 stale. 



Study the external characters of the animal. The most dis- 

 tinctive feature is found in the feathers, which clothe almost the 

 entire body and are so arranged on the fore limbs and tail as to 

 enable it to fly. Feathers are highly specialized epidermal struc- 

 tures and are allied to reptilian scales ; they are present in all birds, 

 and in no other animals. Feathers are not only of great importance 

 to the bird in enabling it to fly, but are also very effective in check- 

 ing the radiation of heat from its body, as they form a warm outer 

 covering. It is largely because of the development of feathers 

 that birds have become warm-blooded animals. The ordinary tem- 

 perature of a bird's body is about 105 ° F., varying a few degrees 

 in different species. 



Note the three kinds of feathers,— the contour feathers, down 

 feathers, and pinfeathers. The contour feathers form the outer 



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