Xvi INTRODUCTORY OBSERVATIONS, 



to the eggs : few frogs are found near a pool 

 which has been black with tadpoles. Let a leaf, 

 or a particle of animal fubftance, fall into a little 

 water, myriads of animalcula will be produced ; 

 but fimple evaporation of the water, an event 

 that muft enfue, is inevitable deftrudion to the 

 whole. Although the period of exiftence is li- 

 mited, few animals die a natural death. The 

 war, which inceifantly rages among the whole, is 

 a never failing fource of deftruclion. The 

 ftronger prey on the weaker ; and thefe on ani- 

 mals that are lefs powerful than themfelves. The 

 juftice of Nature might be arraigned : Why arc 

 fome provided with horns, tulks, orpoifon, while 

 others have no fuch means of defence ? Thou- 

 fands of animalcula are apparently but a fimple 

 veficle, without vifible organs external or inter- 

 nal : they burft on contaft with the air alone. 

 All this deftrudion is neceflary ; the earth would 

 be overilocked ; and even thofe animals, now 

 living in amity, would make each other a prey. 

 Death muft thus be the indifpenfible attendant 

 on life, unlefs propagation were to ceafe. 



The ftrudure of fome animalcula, fuch as it 

 •appears to us, cannot be more fnnple ; but the 

 organization of many is certainly very complicat- 

 ed, no lefs fo than that of animals a thoufand 



times 



