Microscopical Essays. 



27.1 



Each organ apt to each precarious ftate, 

 As for eternity, defign'd complete. 



Of all the productions of nature, infe&s are the mod numer- 

 ous, and multiply moll; their fecundity is prodigious, their 

 multiplication aftonifhing ; the vegetables which cover the furface 

 ©f the earth bear no proportion, to their, multitudes, every plant 

 fupporting a number often of fcarce perceptible creatures ; of 

 the fatal eflfe&s of their prodigious multiplication, our fruit trees, 

 &c. are too often a deplorable teftimony. On the continent 

 whole provinces often languilh in confequence of the dreadful 

 havock made by the minute, but innumerable, holts of infeels. 



The following is anexperiment ofM. Lyoneton the generation 

 of a moth whichcomes from the chenille a brolfe : out of a brood 

 of Q^o^eggs, that he had from a.fingle moth of this kind, he took 

 So, from which he got, when, they were arrived at their perfect 

 Sate, 15 females; from whence he deduces the following con- 

 fequence: if 80 eggs, give 15 females, the whole brood of 350 

 would have produced 65 ; thefe 65, in fuppofmg them as fertile 

 as their mother, would have produced 22,750 caterpillars, among 

 which. there would have been at leaft 4265 females, who would 

 have produced for the third, generation. 1,492,750 caterpillars. 

 This number would have been, much larger if the number of fe- 

 males among, thofe which were fele&ed by M. Lyonet had been 

 greater. M- de Geer. counted in. the belly of a modi 480 eggs, 

 reducing thefe to 400, if fuppofmg. one-fourth only of thefe to be 

 females, and as fruitful as their mother, they will give birth to 

 40,000 caterpillars for the fecond generation ; and for the third, 

 fuppofmg all things equal, four millions of caterpillars. It is. nor 



Reprizing, 



