BIRDS 



69 



The ankle region of a bird is the joint half-way up the leg (Fig. 51, A). 

 What is commonly regarded as the bird's foot consists often of 

 three toes that point forward, and one that extends backward. 

 Ordinarily the parts of the leg below the ankle are covered with 

 scales, and the tips of the toes are provided with claws. 



53. Study of a hen's egg. (Optional home work.) 

 Secure the egg of a hen or other domestic bird, and study it as 

 follows : 



1. Describe the difference in the shape and size of the two ends of 



the egg. 



2. Carefully crack the shell at the larger end and remove the pieces 



of shell. 



a. State what you have done and describe the membrane that 

 lines the shell. 



6. Carefully cut this membrane and note that the liquid con- 

 tents of the egg do not completely nil the eggshell in this 

 region. This cavity is called the air space. Describe the 

 position of this air space. 



shell 



volk 



white 

 of egg 



FIG. 52. Egg of a hen. 



