50 



to the unassisted eye except when in mass, as we often 

 see in swamps, where they appear as an iridescent 

 scum on the surface of the water in still places or in 

 the spoor of some heavy animal. They were formerh' 

 supposed to belong in the animal kingdom, but are 

 now classed among the lower forms of alg«, and have 

 a shell or case of silica, which passes undigested 

 through fish and turtles. These diatoms form the 

 principal food of the oyster, and naturalists have re- 

 corded and named something like 4000 species of 

 them, but we will not go into the subject so deeply. 

 Suffice it to say that the microscopic vegetables can 

 swim in most cases and suppl^^ food for animals also 

 microscopic in their young stages, such as the daphnia, 

 Cyclops, and other forms of entomostracans which in 

 turn feed young fishes. 



To be complete such experiments should begin in 

 Februar\% when the earliest trout of the year may 

 begin feeding ; but these experiments began in April, 

 in time, however, for the production of food for the 

 later hatch to get their first meal. The water now on 

 Long Island was a trifle warmer and presumably more 

 favorable to the production of such life as was desired. 

 The temperature of the water during the season was 

 as follows, mean temperatures only for each month 

 being given in scale of Fahrenheit : 



Rocker}-. ist Pool. 2d Pool. 3d Pool. 4th Pool. 



April 56.5 58.10 59 59.75 60 



May 58.5 60 61.25 62 62.10 



June 62.75 64.10 65 65.75 66.25 



July 69.25 73.25 75.10 76 78 



August 72.75 74.5 76.25 76.75 77.50 



With August the record ended. Neither time nor 

 inclination allowed further observations, for the season 

 had covered the production of food during the most 

 critical period of the life of a baby trout. 



The "Rockery" received the first water from the 



