48 THE NATURAL HISTORY AND HABITS 



the backs were distinguished the one from the other. 

 All this kind of monstrous productions die in four or 

 five weeks after their joint bag or belly is emptied ; 

 for as each endeavours to follow its own direction in 

 pursuit of food, and both hinder one another, neither 

 of them is capable of performing its intentions : it is 

 impossible that either head can receive its proper 

 nourishment, therefore they must starve. All mon- 

 strous productions in the human and other animal crea- 

 tions, with a joint stomach, are produced where an egg 

 is fructuated by more than one spermatic animalcule. 

 "All observations made on trout and its artificial 

 method of breeding hold good with regard to salmon. 

 (Signed) " S. L. JACOBI." 



I would not have inserted Mr. S. L. Jacobi's letter 

 at full length, had it not been for the last paragraph, 

 in which he says, " that all observations made on trout 

 and its artificial method of breeding, hold good with 

 regard to salmon ;" for although he has given a full 

 account of boxes or troughs, and the breeding of 

 trout, his observations differ materially from what we 

 find in the habits of salmon ; for spring water from 

 rocks, or a hard stony bottom, is not the best for breed- 

 ing salmon in ; for salmon know their own rivers by 

 the water or otherwise, and they spawn there natu- 

 rally ; and of course the water from that same river 

 must be the best to breed them in artificially. The 

 spawning season in Germany seems to be much 

 shorter than ours, for the letter says that it is only 

 from the latter end of November to the latter end of 

 January, or the 1st of February, while our spawning 

 time is from the middle of September to the middle of 

 March, the throng from the middle of November to 

 the middle of December, and from appearance of the 

 fish we are likely to have them earlier and later than 



