XIV INTRODUCTORY OBSERVATIONS. 



carp, 383000 in a tench, 546000 in a mackrel, 

 992000 in a perch, and 1357000 in a flounder. 

 But cf all fifhes hitherto difcovered, the cod 

 feems the mofl fertile. One naturalift computes 

 that it produces more than 3686000 eggs ; an- 

 other, 9000000 ; and a third, 93444000. Here 

 then are eleven fifhes, which, probably in the 

 xiourfe of one feafon, will produce above thirteen 

 millions of eggs ; which is a number fo aflonifh- 

 ing and immenfe, that, without demonftration, 

 we could never believe it true. 



Perhaps the innumerable multitude of animals 

 in exiflence is lefs influenced by the numbers 

 produced at a time than by frequent and early 

 propagation, by the hazard of deflrudtion to 

 which the young are expofed, and alfo, it is pof- 

 fible, by fome females being more numerous than 

 males. Many infefts generate but once in their 

 whole lives. It has been calculated, that two 

 females, of the animals mofl loathfome and dif- 

 gufling to the human race, may fee ten thoufand 

 dcfccndents in eight weeks ; that above fourteen 

 thoufand may, in the fecond generation, come 

 from a fpider ; and a common flefli fly have feven 

 hundred and forty thoufand young in the third 

 month. None of thefe animals are at firfl; very 

 fertile, compared with others. But what are all 



their 



