94 OUTLINES OF NATURAL HISTORY. 



some birds can likewise employ the hind-feet in seizing 

 objects. 



The entire body of the Goose is covered with a close 

 covering of those peculiar appendages of the skin which are 



Fig. 43 —The Grey Lag Goose {Anser ferus)'. After YarrelL 



known as feathers. The lower portion of the legs and 

 the beak are iinfeathered, but the head, neck, and body 

 are protected by a dense plumage, which serves two 

 purposes. In the first place, since it conducts heat very 

 imperfectly, the plumage serves to retain and conserve the 

 heat generated witliin the body of the animal. The 

 Goose, therefore, though spending a portion of its time 

 in a medium so cold as water, whilst it is a " hot-blooded" 

 animal, is nevertheless able to keep its temperature up to 

 as high as about ioo° or a little over. In the second 

 place, the plumage is kept oiled by the oily secretion of 

 certain glands near the tail, and the bird is thus enabled 

 to enter the water without getting wet. 



The feathers carried by the wing are longer than those 

 which cover the body, and are the organs which propel 



