THE FLYING FOX, OR ROUSSETTE. 



127 



" Considering how little their vision is adapted for day duty, it was interesting to 

 notice the systematic manner in which they directed their flight : one which arose some 

 time after the others, taking immediately the right direction to follow and join the main 

 body of fugitives." 



In this latter passage is mentioned one distinguished peculiarity of these creatures, 

 namely their habit of flying in long lines, somewhat after the manner of rooks return- 

 ing to roost 



" The blackening train of crows to their repose." 



One bat seems to take the lead, and the others follow at short and irregular intervals, 

 pursuing the same course as their pioneer. 



The bats which belong to this genus (Pteropus) are remarkable for the fact that they 

 possess fewer vertebrae than any other known mammalian animal. In the entire spinal 

 column there are but twenty-four of these bones ; this paucity of number being caused 

 by the entire absence of a tail. 



The hair with which the bat tribe is furnished, is of a very peculiar character, and 

 although closely resembling the fur of a rat or mouse when seen by the unaided eye, is 

 so unique in aspect when seen under a microscope, that a bat's hair can be detected 

 almost at a glance. Each hair is covered with very minute scales, which are arranged 

 in various modes around a central shaft. 



The accompanying figure exhibits the central portion of a hair taken from one of the 

 Indian bats, magnified five hundred diameters, or two hundred and fifty thou- 

 sand times superficially. Near the root, the hair is almost devoid of these 

 scales, and therefore appears much smaller than the central and terminal por- 

 tions. Some of these external scales bear a close resemblance to the scales 

 which are placed on the surface of a butterfly's wing ; but can easily be dis- 

 tinguished from them by their smaller size, and the absence of the striated 

 markings that are found on the scales of the butterfly's wing. 



The strange similitude between the bat's hair, and the plant which is pop- 

 ularly known by the name of " Mare's-tail," cannot but strike any one who is 

 in the least acquainted with botany. It may be, that so remarkable an out- 

 ward resemblance would not exist unless there were some cause, at present 

 hidden, which would account for it. 



Before leaving the study of the bats, we must take a cursory view of the 

 strange condition of life in which these animals pass the colder months of 

 the year, which condition is known by the name of hibernation, because it 

 takes place in the winter. 



The insect tribes on which the bats chiefly subsists, and wholly so in this 

 country, are either quiescent during the winter months, or are abroad in such 

 limited numbers that they could not afford a subsistence to the bats or swal- 

 lows. The latter creatures meet the difficulty by emigrating to more genial 

 lands, and there finding the food which they would lose in these cold climes ; 

 but the former are obliged by the laws of their being to remain in the country 

 where they were born. It is evident, therefore, that unless some provision 

 were made for them during the insectless time of year, every bat would perish of 

 hunger. 



Such a provision exists, and exerts its power by throwing the bats into a deep 

 lethargy, during which they require no food and take no exercise, but just live 

 throughout the winter in a state of existence that seems to partake more of the vege- 

 table than the animal life. 



During hibernation, the respiration ceases almost wholly, and if it takes place at all, is 

 so slight as to defy investigation. The air in which these creatures pass the winter seems 

 to undergo no change by the breath, as would be the case if only one inspiration were 

 made ; and, strangest of all, the animal seems capable of existing for some time in gases 

 that would be immediately fatal to it in the waking state, or even without any air at all. 

 The temperature, too, sinks to that of the surrounding atmosphere, although as a general 



HAIR OF 

 INDIAN BAT. 



