Natural History of their Generation. 323 



now proceed to give the inventor's discovery in his own 

 words : 



Sir, — As I observe from the Literary Mercury of Al- 

 tona. No. 20, 1764, that the Royal Prussian Society of 

 Sciences have taken into consideration my invention of 

 breeding trouts and sah-non, wherein I have observed that 

 th«t lecture thereon must have been pronounced on an mdif- 

 fcrent and partly an erroneous system ; and that a Northern 

 Society 'of Sciences lias, in an Essay on the natural Gene- 

 ration of Fishes, placed that which I had observed, after 

 frequent experiments, among the desiderata; — at Peters- 

 buriih and several other places they have considered this 

 method of an artificial breeding of trout and salmon, as a 

 false chiniiera. I am aware that naturalists are frequently 

 furnished with matter to search for further discoveries after 

 an invention is made public, and that critical examinations 

 will clear un any doubtful opinions on a firm basis ; I have 

 therefore been led to further experiments, to find out the 

 true causes; and hov*' duplicate bodies, in the human lis 

 well as in the whole animal creation, are generated ; which, 

 though they have a double body, yet have but one stomach. 

 I have thought it a duty incumbent on me to lay my ob- 

 servations on this sul)ject, as well as on others, before the 

 public. It would be needless, and not to my present pur- 

 pose, to mention every trifling experiment which I made 

 within the first sixteen years before my conclusions were 

 drawn, and in twentv-four years more afterwards, on the 

 artificial increase of trouts and salmon. Perhaps I may be 

 induced hereafter to give more circumstantial accounts on 

 this subject. 



The box, or trough, or water-bed, in which the eggs 

 animated with the milt or sperm of the male trout are scat- 

 tered, needs no particular form ; yet it will not be unne- 

 ccsbary to give a deacriplion how my own are made. 



§1. 

 (l) T had boxes made of several woods, (but I found oak 

 to be the best,) of about tvielve foot long, one foot and a 

 half wide, and six decimal inches deep. 



(i;) At the head of the trough, where the u-ater is to run 

 in, is laid a thick board about two and a half or three in- 

 hcs thick, about a loot wide, and as long as the trough is 

 .. ide ; in the middle of this board is made a hole six inches 

 long, and about four inches wide in the clear, with a rabbet 

 on all the lour sides of this hole about an inch and a half 

 wide and deep, so as to admit a square frame with anaper- 

 X 3 ture 



