FISH ACCLIMATISATION. 393 



that the instructions you gave me in fish-hatching a few years ago 

 will result in my having a large part of the lake at Burghley full 

 of fine trout of various species. I have lately dammed off the part 

 above the bridge, and after taking a crop of oats and seeds off, am 

 now gravelling the bottom, after clearing out the mud. 



Enclosed I send you the observations made by my valet (Deane), 

 while attending to the hatching of the ova sent me from various 

 ■parts.i The ova from Switzerland generally turn out well ; but the 

 sender should' be more careful about the packing of the ova, which 

 are often sent in too crowded a state. 



Truly yours, Exeter. 



' Burghley House. 



December gth, 1873. — Arrived at Burghley per ' Cuba ' from New York : 

 Salmon-trout, brook-trout, and white-fish. The latter were mostly all dead, 

 and very much clotted together. I think, perhaps, they were too thickly 

 packed. The salmon-trout were much better, and the brook-trout stood the 

 journey very welL Placed the ova In the boxes. 



SALMON-TROUT. 



15th. Ova commenced to hatch. Very few dead eggs among brook-trout. 

 Most of the white-fish eggs dead. 



2ist. A good number of the salmon-trout hatched out. 



aSth. Most of the salmon-trout hatched. No brook-trout hatched. Eggs 

 looking well, ,very few dead. 



White-Fish. — Not a good one to be seen. 



Observations on the Treatment of Trout Ova. 



The temperature of the water for the trout eggs should be from 40° to 4S°. 

 Anything above 50° is weakening ; it will hatch them out sooner, but will in- 

 crease the number of deaths. 



The eggs from America are packed much better than those from Switzer- 

 land, and arrive in better condition, though they must be a longer time on the 

 journey. , 



In placing the eggs in the troughs, equally distribute them over the gravel 

 with a feather ; and it is better, if possible, not to let them touch each other, 

 as the bad ones soon contaminate the good, and they adhere to each other. 

 The white eggs, or dead ones, should be taken out every morning. When I 

 have missed a morning from want of time, I find more than double the number 

 of dead eggs the next morning. 



When they begin to come out of their shell, increase the supply of water. 

 At first I used to have perforated zinc over the outflow of the troughs, to pre- 

 vent the trout passing down into the lower troughs ; but the zinc soon gets 

 stopped up by the little things being drawn against it. Then the water flows 

 over, taking with it the best fish. Let them have a free passage from the top 

 trough to the bottom one. Do not put any eggs in the lower trough ; then it 



