THE GNAT AND TIPULA. 19 



its kind, and enclosed 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 extra- 

 ordinary animals propagate without the use of 

 copulation, without any congress between the 

 male and female, but in the manner of vegetables, 

 the young bursting from the body of their pa- 

 rents, without any previous impregnation. At 

 the sixth generation, however, their 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 sometimes heard to hum about our beds at 

 night, and keeps off the approach 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 with 

 clouds of those famished insects ; and they are 

 found of all sizes, from six inches long to a mi- 

 nuteness that even requires the microscope to 

 have a distinct perception of them. The warmth 

 of the mid-day sun is too powerful for their con- 

 stitutions ; but when the evening approaches, 

 neither art nor flight can shield the wretched in- 

 habitants from their attacks though millions are 

 destroyed, still millions more succeed, and pro- 

 duce unceasing torment. The native Indians, 

 who anoint their bodies with oil, and who have 



