MAMMALS OF THE AIR 333 



extinct in the interior of the body. The lungs, the heart and the 

 other organs continue their work slowly but uninterruptedly." Thus 

 it is essential that, even with this small amount of work, the com- 

 bustion of food material must take place. Hence the superabundance 

 of its food during the mild seasons is stored up, and "this fat by 

 degrees enters the circulation, and is conducted thence to all the 

 organs in which it undergoes combustion. In this manner the 

 needful quantities of heat and force are continually produced afresh, 

 so that, though the animal machine works slowly, it is not brought 

 to a standstill." 



Bats, being insect or fruit eaters, are naturally enough found only 

 in those countries where an abundant food supply is forthcoming. 

 Consequently their distribution in the world is rendered explicable 

 from their mode of life. In a very cold country, where insect life 

 is at a discount, it is obvious that this flying mammal would, if it 

 inhabited it, have a sorry time, for, in view of the long Winter and 

 the extreme cold, it would undoubtedly perish from want of food 

 or loss of heat would, in fact, either starve or freeze. In spite of 

 this we are told that at least one species is found within the Arctic 

 Circle. 



These creatures have for long been regarded with superstition 

 and, indeed, dread by many country people. These latter call 

 them Flitter Mice, and having done that their practical acquaint- 

 ance with them begins and ends. Owing to their noiseless flight 

 and nocturnal exploits, these harmless beasts were, once upon a 

 time, looked upon as evil spirits, and two stupid notions which are 

 hardly worth giving further publicity to, are that they eat up the 

 bacon in the larder and sometimes entwine themselves in the hair 

 of people. 



That Bats are beneficial animals goes without saying. They 

 perform useful work in the economy of Nature, and the insectivorous 

 species take up at nightfall the good deeds carried out by insect- 

 eating birds during the day. It has been conclusively proved that 

 Bats in feeding, for instance, upon a certain kind of moth, known 

 as the Processional Moth, do inestimable good, for in Germany at 

 the beginning of the nineteenth century "a large number of oak- 

 trees were cut down in the neighbourhood of Hanau, in the 

 hollow trunks and branches of which thousands of Bats were found 

 in the hibernating condition. In sawing and splitting up these 

 trees many of the animals perished from the cold, many were killed 



