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 half- 
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.1 5S. Fario . «+ measures ‘20 inch or # nearly 
5 25. Fontinalis . ss *23 inch or & nearly 
6 3 S. Levenensis 45 24 inch or + nearly 
55 458. Fario . ° » 26 inch or 3 full 
” 5 S. Ferox . FS 26 inch or } full 
Ps 68. Fario. . 53 *30 inch or 3 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 
