Of the flea. 



JjEING defirous to know how long time was requiflte for the egg 

 of a Flea to produce a perfect Flea, I fat about making experiments 

 to afcertain that fact ; but it was not till after many trials that I 

 could make a regular feries of fuccefsful obfervations. 



In the month of July, I enclofed feveral Fleas in a glafs, that 

 they might lay their eggs ; the worms or maggots hatched from 

 their eggs, I nurfed with all the care I was able, feeding them 

 every day with flies, which I firft killed ; thefe they devoured with 

 great avidity, and thereby were very fpeedily increafed in lize. My 

 obfervations on this fubject are as follows : 



On the 0th of July the worm came out of the egg. 



On the 17th of July the worm appeared all over white, from 

 whence I concluded that it was near dying ; I twice offered it frelh 

 flies for food, but it would not eat, and appeared to me to be mo- 

 tionlefs, but viewing it with the microfcope, I faw that it was 

 employed in fpinning round itfelf a web or covering. 



The 21st of July, this worm was changed into an aurelia or 

 chryfalis, which was of a tranfparent white. 



The 25 th of July, this chryfalis aflumed fomewhat of a red colour, 

 which continually grew deeper and deeper. 



The 30th of July in the morning, it was entirely red, and in 

 the evening the Flea it contained was leaping about the glafs. 



Hereby we fee that in the middle of the fummer, in four days 

 time after an egg is laid by the Flea, it produces a worm or mag- 

 got, which in eleven days attains to its full growth, in four days 

 time it is changed into a chrysalis, and in nine days more it becomes 

 a perfect Flea. 



Now if we lay it down, that it is with these creatttres, as \\ ith 

 moft fmall animals, which in like manner undergo a change, (at 



YoL. II. E 



