146 Fortieth Annual Meeting 



employed at Mammoth Spring, or "mijinko," as collectively 

 called in Dr. Smith's book, were those of rank plant growth 

 that were dry all winter or else those with practically new 

 clay bottom that were dry all winter. 



(5) Very slow change of water in ponds is conducive to 

 the production of "mijinko," — as the Mammoth Spring 

 lake, and Spring River resulting from the spring and lake, 

 and Warm Fork, a stream 40 miles long, all contiguous to 

 the station, contain no "mijinko" in quantity, these waters, 

 in fact, being practically barren of the "mijinko" forms, 

 while the ponds of the station are marvellously stocked 

 with them. 



(6) Earth embankments and other surrounding lands 

 that are rich in nitrogen-producing substances contribute 

 to "mijinko" production. The enormous numbers of "mi- 

 jinko" in the station ponds are, in part, doubtless, due to 

 the presence in recent years of pens of stock — cattle, hogs, 

 and poultry — that were sent away in carload lots from 

 Mammoth Spring railroad station. 



(7) "Mijinko" are not found in the rank "water moss" 

 vegetation at Mammoth Spring but in open, deep water near 

 the outlets of ponds and massed in greatest profusion above 

 bare areas of bottom where no plants grow. 



(8) Greatest numbers of "mijinko" were observed 

 when the water temperature dropped, in April, to 40° F. 

 The "mijinko" do not disappear when the water temperature 

 goes up to 80° (June). 



(9) "Mijinko" assemble themselves around objects in 

 the water, such objects as artificial nest shields, stakes, etc., 

 and especially massive outlet gates or "standpipes." 



(10) It is better to rear black bass fry in ponds where 

 they can capture their own food than in cement or other 

 tanks where the food has to be supplied to the fish from 

 day to day for the reasons that (a) capturing "mijinko" 

 is a slow and expensive operation, {h) the fish from ponds 

 are more numerous at shipping time than are those reared 

 in tanks, and (c) the fish grow relatively faster and larger 

 in ponds. 



