THE USE OF CERTAIN MILK WASTES IN THE PROPAGA- 

 TION OF NATURAL FISH FOOD 



By G, C. Embody 

 Cornell University, Ithaca, New York 



Within the last few years there has been a notable increase in the 

 number of commercial plants concerned in the manufacture of 

 various milk products. These plants include mere skimming stations, 

 cheese, butter and casein factories, and condenseries. In a great 

 many cases they are located near important fish producing streams 

 which constitute convenient places for the disposal of wastes. 

 Whether the procedure in thus disposing of wastes is detrimental or 

 otherwise to the life in the stream, depends upon a number of dif- 

 ferent factors which cannot be discussed here. It is known, how- 

 ever, that in many cases streams have been polluted to a degree that 

 is very disastrous to aquatic life. 



During the progress of some experiments undertaken by my 

 colleague. Dr. P. W. Claassen, to show the effects of such wastes 

 upon stream life, some phenomena were observed that seemed to bear 

 directly upon the problem of growing natural food for fish. The 

 writer was thus prompted to carry on some special work with this 

 end in view and the following notes constitute a brief statement of 

 certain results thus far obtained. 



The experimental procedure consisted in pouring into basins of 

 stagnant water known amounts of several diflterent wastes. Sour 

 skim milk and whey were the two which gave the most significant 

 results and at the same time could be easily obtained in sufficient 

 quantities to render their use practicable. Other wastes were tried, 

 such as floor washings and the effluents from Imhoff tanks, septic 

 tanks, lath filters, etc., but these were either too highly diluted or so 

 changed as to render their use at this time impracticable. 



The basins in which the experiments were run consisted of wood 

 hatching troughs of regulation size, wood wash tubs, larger concrete 

 rearing ponds and small ponds with earth sides and bottom. None of 

 these basins was planted with mother organisms, either plants or 

 animals, except for those which came in with the water at the time 

 of filling the basins, and care was taken to eliminate all of the higher 

 aquatic plants and predacious animals such as certain aquatic beetles, 

 bugs, dragonfly and damselfly nymphs. Thus the only organisms 

 started with were a few micro-organisms found in the plankton. It 



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