8 NATURAL HISTORY OF THE SALMON. 



manner in which the eggs of fish are impregnated 

 is wholly unknown. There is no great use in en- 

 tering into a further detail on this head, yet we 

 shall say a little more about it hereafter. Though 

 the grand distinction of fish is between those which 

 are cetaceous and those which are cartilaginous, 

 yet there is no reasoning by analogy, or drawing 

 conclusions from one animal to another, or even 

 forming an opinion on probability, as to their in- 

 crease. The fecundity of the salmon is very great, 

 the roe of a single one amounting, as I have been 

 informed by a person who counted it, to about 

 600,000. This experiment was made in the usual 

 way, namely, by first weighing and then counting 

 a certain portion, and afterwards weighing the 

 whole mass. Yet this increase bears no sort of 

 proportion to the number of pea in many other 

 fish. The sturgeon produces the greatest number 

 that I ever read of, being no less, according to 

 Leuwenhoek, than 150,000 millions, an amount 

 equal to that of all the inhabitants of the earth ; 

 the female cod-fish gives 9,340,000 ; and the com- 

 mon crab 4,334,000. The porpoise produces only 

 one, and yet porpoises are more plentiful than stur- 

 geons. There seems to be no positive general rule 

 in Nature upon this subject : such is the extent 

 and the variety of exceptions, that we are forced 

 to the necessity of considering every animal dis- 

 tinctly and individually. What analogy proves to 

 us that if the claw of a crab be torn off another 

 will supply its place; that the polypus may be cut 



