SALMON AND TROUT CULTURE. 453 



TREATMENT OF THE OVA. 



As soon as impregnation takes place, the micropyle closes, 

 and water cannot enter except through violent concussion. 

 When the 'germ' has risen, and 'segmentation' begins, the 

 ova should be disturbed as little as possible. After this, if the 

 hatchery is well regulated, nothing short of violence or absolute 

 neglect can prevent the regular progress of nature, and the eggs 

 will, in due time, hatch. 



The period of 'incubation,' as it is sometimes called, extends 

 over fifty to seventy days in water of 46 to 50 Fahrenheit, and 

 during this period the pisciculturist's labours are not very exces- 

 sive, provided he has everything in first rate order, and a good 

 percentage of fertilised eggs. The time occupied in picking out 

 white (that is dead) ova, and any foreign substance which may 

 appear, is inconsiderable, and it is not necessary that this should 

 be done every day ; three or four times a week is often enough, 

 unless the temperature rises, in which case ' fungus ' and * byssus ' 

 grow more rapidly. 



A number of good eggs are sometimes spoilt by the inces- 

 sant disturbance caused in hunting after a few bad ones, and 

 awkwardness in removing them. Personally I allow no 

 one to touch my ova until they have been in the water 

 twenty days, undertaking all the picking over myself during 

 that time. A few minutes at the different troughs is all that is 

 required. 



If ova are sent to the Antipodes, they should be packed 

 and placed on board ship as soon as possible after they 

 are taken from the parent fish. The voyage is too long if 

 packing is delayed until the eyes appear; and as the tem- 

 perature in Australia and New Zealand is at its highest in 

 December and January, it is advisable to send eggs of late 

 spawners, so that they arrive there at a cooler season, viz. April 

 or May. 



