398 HISTORY or 



about in search after some commodious tord, or standing water, 

 where she may produce her progeny, which would be soon 

 washed away and lost, by the too rapid motion of any running 

 stream. The little brood are sometimes so numerous, that the 

 very water is tinged according to the colour of the species, as 

 green, if they be green, and of a sanguine hue, if they be red. 



These are circumstances sufficiently extraordinary in the life 

 of this little animal ; but it offers something still more curious 

 in the method of its propagation. However similar insects of 

 the gnat kind are in their appearance, yet they differ widely from 

 each other in the manner in which they are brought forth, for 

 some are oviparous, and are produced from eggs : some are vi- 

 viparous, and come forth in their most perfect form ; some are 

 males, and unite with the female ; some are females, requiring 

 the impregnation of the male; some are of neither sex, yet still 

 produce young, without any copulation whatsoever. This is one 

 of the strangest discoveries in all natural history ! A gnat sepa- 

 rated from the rest of its kind, and inclosed in a glass vessel, 

 with air sufficient to keep it alive, shall produce young, which 

 also, when separated from each other, shall be the parents of a 

 numerous progeny. Thus, down for five or six generations, do 

 these extraordinary animals propagate without the use of copu- 

 lation, without any congress between the male and the female, 

 but in the manner of vegetables, the young bursting from the 

 body of their parents, without any previous impregnation. At 

 the sixth generation, however, {heir propagation stops ; the gnat 

 no longer produces its like, from itself alone, but it requires the 

 access of the male to give it another succession of fecundity. 



The gnat of Europe gives but little uneasiness ; it is some- 

 times heard to hum about our beds at night, and keeps off the 

 approaches of sleep by the apprehension it causes ; but it is very 

 different in the ill-peopled regions of America, where the waters 

 stagnate, and the climate is warm, and where they are produced 

 in multitudes beyond expression.* The whole air is there filled 



• Humboldt tells us, that " between the little harbour of Higuerote and 

 the mouth of the Rio Unare, the wretched inhabitants, to protect them- 

 selves from gnats, are accustomed to stretch themselves on the ground, and 

 pass the night buried in the sand tliree or four inches deep, exposing only 

 the head, which they cover M-ith a handkerchief." Stedraan also mentions, 

 aa a proof of tlie dreadful state to \\ hicli he and his soldiers were reduced 



