148 Tmcnty-ninth Annual Meeting 



the end there, instead of using the dam across there, they use a 

 tube with a rubber band around it. If you want it higher you 

 raise it up; you can have it one inch deep or higher. 



Mr. Ravenel: I would Hke to ask Mr. Clark how many fry 

 he carries in relatively the same space? 



^Ir. Clark: I have been very much interested in Mr. 

 Thompson's paper and of course have always been interested in 

 those models that he has shown, but I hardly think he brings 

 them forward as new inventions, do you Mr. Thompson? 



Mr. Thompson: No. 



Air. Clark: They have been in use, all of the models, for 

 quite a number of years and are all good. Of course his system 

 there of slides is nothing but a remodification of the Clark- 

 Williamson box, and of the Williamson box ; we are using them 

 right along, only instead of tin ours are wood, but the plan and 

 the whole system are practically the same. The idea of forcing 

 the current from underneath is all right. The current in the 

 Clark box is downward while they are hatching the eggs, but 

 after the eggs are hatched the box is turned around and then the 

 current is upward. Our system, as perhaps a good many of you 

 have read, is thoroughly described in the Manual of Fish Cul- 

 ture, and it tells there just the number of eggs we carry on a 

 given number of trays. Each box or compartment in the Clark- 

 Williamson hatching trough is ig by lo by 12 inches, and holds 

 60,000 lake trout eggs, 6,000 on each of the inclosed ten trays. 



The President: Carry as fry? 



Mr. Clark : Carry them forward to the point where the 

 eggs are ready to hatch, then we reduce them to 40,000 and carry 

 them in the same space until they are hatched and until the fry 

 are ready for distribution or feeding In other words, we leave 

 from these 60,000 eggs 40,000 for hatching and rearing. 



The President : And carry them until just before the sac is 

 absorbed? 



Mr. Clark: Until the sac is absorbed. 



Mr. Handy: I would like to ask how much water you let 

 through the trough? 



