INTRODUCTION. 23 



quently found in a common Carp, tho' far 

 Ihort of the Number contain'd in a large Cod, 

 is fo furprifing, that we may be fully fatif- 

 fied Mr. Leuwenhoeck's Calculation is juft. 

 When we come to fearch into the wife End 

 of this amazing Fertility, we are immediately 

 convinced, that it is not to replenifli either 

 the Rivers, or the Sea, with the fame Quan- 

 tity of Fifh as there are Eggs : For were it 

 fo, the Ocean itfelf would fcarce be able to 

 contain them. 'Tis manifeft, however, that 

 that there is a double Intention in this Fecun- 

 dity ; in the firfl Place, to preferve the Spe- 

 cies, whatever Accidents may happen ; and 

 in the next, to furnilh the furviving Fifh with 

 a plentiful and fucculcnt Subfiftence. 



Thus we perceive, in fome meafure, the 

 Manner in which the Fifh are nourifhed and 

 preferved. There are fuch an infinite Num- 

 ber of Weeds, Worms, Shell-fifh, Eggs, 

 Roes, and minute Fifli lodged within the 

 Waters, that we need be in no Manner of 

 Concern for the Inhabitants, with refpedl to 

 their Provifions. They have, we perceive, 

 their certain Allowance. — But then their Ali- 

 ment lies conceal'd, or flies before them ; and 

 we can difcern nothing in thefe Fifh but a 

 Head, a large inadlive Body, and a Tail. 

 As they have fo few Organs, we naturally 

 afk, how are they capable of advancing, 

 fwimming, and feizing on their Prey ? To 

 folve this we muft confider, that the Form, 

 or Figure, of all Fifh in general being ftrait, 



an 



