78 SOME INSECT EATERS 



obstruction. Cords have been suspended in dark rooms 

 to test the powers of the bats, which invariably avoided 

 them. In sleeping, the bats cling to the rocks by their 

 feet, hanging head downward. The thumb is provided 

 with a hook, which they use in walking, though they are 

 very clumsy when on the ground and make but little head- 

 way. Certain bats have a sucking disk (Fig. 

 57) by which they cling to rocks. 



The bats, being mainly insectivorous, are de- 

 prived of their food at the approach of cold 

 weather. Unable to migrate, as do the birds. 



Fig. 57.— they hibernate, or enter upon a long winter 

 Sucker on 

 THE Wing sleep. Snugly packed away in caves and the 



OF A Bat. trunks of trees, they sleep away the days until 



spring comes again with its horde of insect life. Many 



interesting experiments have been tried with these sleeping 



bats, showing how like death the sleep is. Air that has 



surrounded them has been analyzed, and did not show 



any evidence of having been breathed. A sleeping bat has 



been placed in illuminating gas for a short time without 



fatal results, showing that nearly all the functions of life 



are at a standstill. During this rest the bats are supposed 



to exist by drawing upon the fat accumulated during the 



active period. The young of bats, one or two at a birth, 



cling to the mother and are carried about by her during 



flight. The sail turned upward with its webs forms a more 



or less perfect pouch for them. 



The so-called vampire bats have earned a disagreeable 



reputation by their habit of attacking horses in South 



America. They are small bats, and have been known to 



stampede a band of horses by alighting on their necks 



