THE EGG HARVEST. 25 



several piles near the tub. Milk-plates are by far the best 

 utensils in which to impregnate trout ova. Earthenware is more 

 suitable than any other material, because, being a very bad con- 

 ductor, the temperature of the water and ova placed in it is very 

 slightly affected by that of the atmosphere. The importance of 

 this is only appreciated by those who have used both metal and 

 earthenware spawning-dishes during intense frost, and compared 

 the results after the ova have hatched. 



The next advantage of milk-plates is the large flat area of the 

 bottom. Before an ovum can be impregnated it is necessary live 

 milt be brought in contact with it, and when the very short time 

 the zoosperms remain active after the milt is diluted is remem- 

 bered, the facilities offered by a large flat surface over a small or 

 concave one are manifest. It is highly improbable the spermata- 

 zoon can enter the micropyle without the aid of water, and the 

 Howietoun experiments have shown the vitality of the milt is 

 much impaired by exposure to low temperatures, or even to air and 

 light. Therefore the custom prevalent among pisciculturists of 

 mixing ova and milt in deep metal dishes, leaving them together 

 for a considerable time, and then washing off the milt, and pouring 

 out the eggs into the collecting-pail, is contrary to common sense, 

 and produces a large percentage of insufficiently vitalised embryos. 

 With milk-plates, 10,000 eggs can be perfectly impregnated by 

 the milt of a single fish, and, although I have no substantial 

 reason, I have a strong prejudice against stripping several males 

 over one dish. 



The operator at Howietoun wears a silk mackintosh apron, 

 partly to keep his clothes dry and clean, but principally to avoid 

 injuring the fish. 



Some years ago it was noticed that large numbers of the 

 spawners were blind of the right eye, and on careful investigation 

 it was discovered that this was due to the eye being injured 

 against the buttons of the waistcoat whilst the fish were being 

 stripped. Since the introduction of the aprons no fresh cases have 

 been found. 



Two wisps of hay are laid on the ground in front of the net, 



