2O4 How to obtain it. 



things work together. Nature has provided them, and we have 

 only to go in and occupy the position that is open to us. A fact 

 that has been observed over and over again is, that where Nature 

 places the fish there are the necessary food supplies, but only up 

 to a certain point. If we wish to go beyond that point we must 

 increase the food as well as the fish. 



I have recently been paying special attention to the cultivation 

 of perch ( ' Perca fluviatilis ), and on investigating the natural 

 breeding grounds I found that where the ova were about to hatch 

 there were myriads of living creatures, all ready for the little fish to 

 live upon when the time arrived for them to require food. Yet we 

 hear of individuals condemning perch culture, because when the 

 eggs are hatched in pure barren water the little fish all die. There 

 is no wonder that they do. The cultivation of the Corregonidce 

 has been condemned on the same ground. The little fish are 

 very small and delicate at first, and as soon as they lose their sacs 

 they die from the same cause. But is that any reason why we 

 should abandon the thoughts of their cultivation ? All the more 

 reason for persevering in it until the difficulty is overcome. 



Having examined some of the waters of the great American 

 lakes, in which the Corregonidce. (white fish) are found in very 

 large numbers, I found the lower forms of life exceedingly abundant. 

 It is on these lower forms that the white fish feed, and the very 

 first discovery of this important fact is probably due to Dr. P. R. 

 Hoy, of Racine. He also found that certain forms were parasitic 

 on the white fish, and it is a noteworthy fact that he failed to find 

 any of these in the stomachs of the fish. This certainly does not 

 apply, however, to all parasitic organisms. 



There is one very remarkable occurrence, and that is that 

 the excreta of fish produces a suitable nidus for the growth of some 

 of these minute forms, and, therefore, what is looked upon as a 

 nuisance to be got rid of may be made a means of promoting fish 

 life. True it is that everything has its use in Nature. We find 

 that decaying vegetable matter provides some of the conditions 

 which foster the growth of these lower invertebrate forms, and we 

 have had some remarkable instances of the effect of this on 

 newly-made artificial lakes. One thing it is necessary to note, 

 however, and that is, that in some cases the organisms partake so 



