248 



Microscopical Essays. 



miration was raifed much higher than before, when I obferved 

 that they would receive no harm, for they had a power of length- 

 ening their tail about an inch, but that they were not left without 

 means of life in a much more increafed depth of water; on 

 adding a quart more water, it was foon found that the apparent 

 tail of the infect was a mere tube, containing within it another 

 much fmaller, yet fufficiently large for the paffage of all the air 

 that was neceflary to this animal, a fine {lender pipe being imme- 

 diately darted up out of this, and extended to the new furface ; 

 on raifing the water two inches higher the pipe was immediately 

 lengthened again as far as was neceflary, and fo on till the limits 

 of the glafs fuffered us to carry the experiment no further." 



Of the Generation of Insects. 



One of the greateft. myfleries in nature is generation, or that 

 power by which the various fpecies of animals, Sec. are propa- 

 gated 5 by which one fmgle individual gives birth to thoufands, 

 or even millions of individuals like itfelf; all formed agreeable 

 .to proportions which are only known to that Adorable W isdom 

 which has eftabliihed them. We {hall never be able to form any 

 adequate conception of this power, till we are acquainted with 

 the principles of life, and can trace their various gradations in 

 different orders of beings. Many ancient philofophers, from a 

 mifconception and perverfion of the fentiments of the more an- 

 cient fages, imagined that infefts were produced from corrupt and 

 putrefied fubftances ; that organized bodies, animated with life, 

 and framed in a moft wonderful manner, owed their origin to 

 mere chance ! Not fo the mod ancient fages ; they taught that 

 every degree of life muft proceed from the fountain and fource of 



ail 



