1896.] on Fish Culture. 41 



has been very largely taken up, and all those who are familiar with 

 it are well acquainted with the names of Herr Max Von dem Borne 

 and others, who have experimented largely and carried the work to 

 great perfection. 



In America, also, a great deal has been done, and the American 

 Government some time ago started a United States Fish Commission 

 which is carried on under Government auspices, and devotes attention 

 not only to the stocking of the rivers and the lakes, but to what is 

 more important, the study of the fish themselves, of the animals upon 

 which they feed, of the plants surrounding them in the waters in which 

 the fish live, and of anything else of importance in connection with 

 them. A great deal of work, and very important work, has been done, 

 and much of our knowledge at the present time has come from the 

 United States and from Canada. 



The principle of the artificial incubation of ova is a current of 

 water. It may be a current flowing or rising up perpendicularly or 

 flowing horizontally. In nature we find the eggs deposited — I am 

 alluding now to those of the salmonidae — in the gravel at the bottom 

 of streams, and we find where they are deposited that the water comes 

 welling up from below through the gravel, and that the eggs obtain 

 thus a sufficient supply of oxygen, and in due course of time hatch. 

 This was followed out for many years by fish culturists, a current of 

 water being caused to flow into the hatching apparatus at the bottom 

 and to flow out at the top, so that it rose up amongst the eggs ; and 

 practically this has been carried out with more or less modification 

 until the present time. 



The hatching apparatus which is used now chiefly in this country 

 consists of a long box, the water flowing in at one end protected by a 

 water board or breakwater, which is simply to break the current and 

 prevent it from washing away the eggs which are placed in the 

 box. It also diverts the current and sends it down to the bottom 

 of the box. The water passes underneath and passes out at a higher 

 level, where we have a screen of perforated metal to prevent the 

 escape of the little fish, and in this box is placed the hatching appa- 

 ratus proper, that is, the trays or grilles upon which the ova are 

 deposited. The grilles now in use are made of glass. We found 

 after trying a variety of substances, that glass is the best of anything. 

 It gives oft' nothing. Wood and metal we know corrode in water, and 

 in some waters some metals corrode very much, and a great deal of 

 loss has been suffered by some who have used metallic trays for the 

 purposes of incubation. The Americans like to do things as we know 

 on a wholesale scale, and, not content with putting a layer of eggs 

 upon the apparatus, they fill a basket, as they call it, half full of eggs. 

 Then they send a current of water welling up from underneath, and 

 of course the effect is that it flows through amongst the eggs, and 

 they find that in due course of time they hatch. I have made very 

 careful inquiries with regard to the result of the hatching of ova in 

 this way, and I have found that the Americans are quite prepared 



