AN IMPROVEMENT IN HATCHING AND REARING BOXES. IO23 



never become tame. They also rise readily to floating particles, and consequently 

 I do not think that the slightest fear need be entertained that the use of these 

 worms as a primary food will train the fry to become ground feeders at a later 

 stage of their existence. T. rivulorum is pretty widely distributed throughout 

 England and the continent of Europe, but I have no idea whether it extends to 

 America. In regard to its introduction into the latter country, it is such a 

 fragile, insignificant creature that I do not think it could, under the influence 

 of an altered environment, do the slightest harm; and if any enterprising pisci- 

 culturist in the United States wishes to give it a trial I shall be very happy to 

 extend to him any assistance that lies in my power. Given a nice, soft stretch 

 of mud, covered by an inch or so of water, and an equitable climate, the mud 

 worm will flourish apace and multiply with a truly surprising rapidity. It has 

 been tried on trout fry in several of the leading hatcheries in England, and the 

 reports I have received concerning it have been of a most favorable character, 

 the only fault to be found with it being that it is an exceedingly expensive food. 

 As the hatcheries mentioned above have had to purchase their supplies from 

 London at the rate of 3 shillings 6 pence per quart, this complaint is quite 

 justified, but if the pisciculturists who make it will only go to the small amount 

 of trouble necessary for laying out a worm bed, they will find that T. rivulorum 

 is a cheap and invaluable food for their fry. 



