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stream, darting about here and there after minute par- 

 ticles of food. The diseased ones wander about listlessly, 

 swiming round and round continually. They may also 

 be known by the size of their heads, which appear much 

 larger than their bodies. The head of a young trout is 

 the largest portion of the fish, even when well, but when 

 aick the fish appears to be all head. 



Before the food sac is gone the trout is often afflicted 

 with a swelling over the sac ; a membrane forms there, 

 swells out large and is filled with a watery substance. 

 We call the disease the "dropsy," or "blue swelling." 

 Sometimes the trout may be saved by making an incision 

 in the swelling and letting out the water ; but as with 

 care only a few of them are affected in this way, it is 

 better for the fish culturist to hatch more eggs than 

 he expects to raise than to bother with a surgery he 

 does not understand. In other words, hatch more than 

 you want, and keep the strongest and best. 



There is a small worm which is one of the greatest 

 enemies which the young fry have. It spins a web in 

 the water to catch the young fish, just as a spider does 

 on land to catch flies. The web is as perfect as that of the 

 spider and as much mechanical ingenuity is displayed in 

 its construction. It is made as quickly and in the same 

 way as a spider's, by fastening the thread at different 

 points and going back and forth until the web is finished. 

 The threads are not strong enough to hold the young 

 trout' after the unbilical sac is absorbed, bnt the web 

 will stick to the fins and get wound around the head and 

 gills and soon kills the fish. It is even more destructive 

 to white fish, which are much smaller than trout when 

 first hatched. The threads spun by this worm seem to 

 be much finer than the common spider's web, and they 



