224 THE ZOOLOGIST. 



because they are too deep in the water. They consequently may 

 have to shed their eggs in the stream, where they become lost, or 

 push higher up to where there will be more chance of their redds 

 being left dry and the ova perishing; even in their annual spawning 

 grounds, where their eggs may have been deposited, severe seasons 

 of drougbt may occasion most disastrous results. Irrespective of 

 season, the eggs have numerous water enemies, as Fresh-water 

 Shrimps, which hunt out the nest, where they are as merciless to 

 the eggs as Rats are to corn in a granary. The larva of the May- 

 fly and of the Dragon-fly, and even some birds, cannot be deemed 

 innocent of joining in this great work of destruction ; while Swans 

 and Ducks enjoy nothing so well as the spawn of fishes, in which 

 taste the Vole or Water Rat appears to coincide. In consequence 

 of the many destructive agencies at work, an ingenious plan of 

 artificial hatching and rearing has been adopted with great success. 

 By regulating the water, droughts and floods are prevented, and 

 many enemies are excluded which run riot among fish-eggs left 

 in a state of nature in our rivers. 



Supposing all to have gone well with the eggs, and some young 

 fish hatched, it does not follow that the fry are always strong and 

 healthy. The temperature of the water ought to range out of 

 doors about 40° or 45°, for if it should rise to 50° the eggs may 

 become prematurely hatched. The higher the temperature the 

 sooner the young appear, and the more weakly they may be 

 expected to be: sometimes the jaws are deformed in the fry, or 

 the spinal column is curved ; even two fish may be connected 

 together, like the Siamese twins ; again, two or even three heads 

 have been seen attached to one body. When the young fish emerge 

 from the eggs they have a large bag, the umbilical vesicle, attached 

 to their stomachs : this contains the nourishment which is to 

 serve them for several (three to eight) weeks' subsistence, and 

 they do not commonly take in any food by the mouth until it is 

 absorbed. Weighed down by it, they lie quietly among the stones 

 at the bottom of the stream, and seek concealment from fish 

 larger than themselves, aquatic insects, and other enemies which 

 would at once commence to feed on them. 



When the fry has become an ounce or so in weight, it is 

 commonly known in our river as the " last spring" or " parr." Its 

 colours are very similar to those of its relative the Common Trout. 

 Several so-called "finger marks" appear down its sides, and 



