450 SALMON AND TROUT. 



to get ova from good ' strains ' of fish, and from large, healthy 

 breeders. If they come from a degenerate breed it is not pro- 

 bable that the offspring will be healthy, nor grow to any great 

 size. Trout brought from Scotch burns, or little Welsh and 

 Devonshire streams will often grow to a large size in more 

 suitable water, although they would never have got beyond balf- 

 a-pound at the most in their native stream. There is a decided 

 advantage in having large ova, for the simple reason that the 

 fish hatched from them are bigger, and able to take much 

 larger morsels of food ; they thus get a good start of their 

 smaller brethren, and, as a rule, keep it. I have found that 

 the largest and best eggs are produced by fish from three to 

 five years old. The size of trout ova varies very much, as the 

 following comparative table will show. 



Sample No. l S. Fario . . measures '2o inch or j'^ nearly 

 2 S. Fontinalis . „ '23 inch or /^ nearly 



3 S. Levenensis 



4 S. Fario . 



5 S. Ferox . 



6 S. Fario . 



•24 inch or \ nearly 

 •26 inch or \ full 

 •26 inch or \ full 

 •30 inch or — nearly 



These measurements are the largest diameters, the eggs not 

 being perfectly round. 



Where fish culture is practised on a large scale, hundreds of 

 thousands, or even millions of eggs are required. At several 

 of my ponds I can safely reckon on 100,000 to 400,000 in a 

 day's spawning. I am under obligations also to several friends, 

 who allow me to take what ova I can get from their water, and 

 I endeavour to make them some return by sending them fry or 

 yearling fish. 



IMPREGNATION OF THE OVA. 



The first principle of modern pisciculture is the fecundation 

 of the ova by artificial means. ' In consequence,' observes 

 Livingston Stone, 'of the discovery that all mature eggs are 



