274 



Microscopical Essays. 



quantities, as to lay wade great part of Europe, producing atmoft 

 unequalled calamities, fwarming in fuch multitudes as to cloud, 

 the air, deilroying all the vegetables ; in Sweden the cattle 

 perifhed with hunger, and the men were forced to abandon their 

 country, and fly to the neighbouring regions.* The far greater 

 part feed only, however, on one fpecies of plant, or at mod on 

 thofe which are fimilar to it ; and the fame fpecies may always be 

 found on the fame plant. 



Mr. de Reaumur fays, that the caterpillar, w T hich infefts and 

 feeds upon the cabbage, deftroys in twenty-four hours more than 

 twice it's weight. If larger animals required a proportionable 

 quantity, the earth would not be able to nourilh it's inhabitants. 



A great number of infecls rejeft vegetable, and- live on animal 

 food ; fome feeking that which is beginning to putrefy, while 

 others delight in that which, is entirely putrid ; others again are 

 nourifhed by the moft filthy puddles, and difgufting excrements .;: 

 fome attack and feed on man himfelf, while others are nourimed 

 by his viftuals, his cloaths, his furniture : fome prey upoa 

 infefts of another fpecies, othersatt ack their own, and harrafs, 

 each other with perpetual carnage.. 



Every animal has its appropriate lice, which feed' on and'infeO: 

 it. M. Rhedi has given an accurate account of a great number 

 of thefe little noxious creatures, accompanied with figures-; but, 

 as if it were not fufficient that thefe creatures mould dwell and 1 

 live on the external part of the body, and fuck the blood of the 



animal 



* Sele& Differtations from the Amoenit^tes Academics^ vol, i, p. 3.98, 



