100 THE UNIVERSE. 



tufts of deformed, closely-set branches, which appear in the 

 tops of the pine-trees, and to which the German foresters 

 give the name of witches' brooms ; strange-looking bunches, 

 which the superstitious wood-cutters of the Hartz fear to 

 touch less they should be struck by a thunderbolt, for they 

 believe these growths attract the lightning. They there- 

 fore call them also thunder -bushes. 1 



In the domain of the infinitely little the physiological 

 phenomena astonish us no less than the extreme slightness 

 of the motive organs ! A single comparison will demon- 

 strate this. 



When we communicate an elevating movement to our 

 arms, and suddenly bring them back to the body, a second 

 of time will scarcely suffice for the act ; but, according to 

 the experiments of Herschel, some insects vibrate their 

 wings several hundred times in this short period ! 



M. Cagniard-Latour affirms that a gnat vibrates its wings 

 500 times in a second. 



Mr. Nicholson goes still further ; he asserts that the vi- 

 brations of the wing of the common fly are as many as 600 

 in a second, since it passes through space at the rate of six 

 feet in this time. But this observer adds that, for rapid 

 flight, we must multiply this number by six, which means 

 that in a second, or the time we require to execute a single 

 movement of one of our members, the fly, with its wing, can 

 perform 3600. The mind is stupefied at such calculations, 



1 Schacht, who has described the witch-brooms at full length, seems to at- 

 tribute them to the stints of insects, which determine an exuberant flow of vital 

 powers to the part where they have been inflicted. He says that these brooms, 

 when they are covered with leaves, look, if seen at a distance, like a great mistle- 

 toe. Schacht, Les Arbres. Bruxelles, 1862, p. 140. 



