226 MORRIS M. WELLS. 



continue the work in his laboratory at that place. The differ- 

 ences in the water supply of the two institutions brought up a 

 number of new questions regarding the reactions of the fishes, 

 and it was decided that to continue the investigation satisfac- 

 torily, more must be known of the effects of acid and alkaline 

 water upon fishes and their reactions. This second investigation 

 was therefore taken up and the results are published in advance 

 of those with the salts, since they bear directly upon the inter- 

 pretation of the latter. A brief comparison of the water of the 

 two institutions will be profitable at this point. 



The water at Chicago is pumped from Lake Michigan and 

 analyses show it to be considerably different in gaseous and 

 solid content from the water at Illinois, which comes from deep 

 wells. In 1912 Alice, who had been working at Chicago on 

 rheotaxis in isopods, came to Illinois, bringing with him a stock 

 of animals. In his paper ('13) he compares the waters of the 

 two institutions, and gives a table showing the differences in 

 the dissolved content. This table is inserted here. 



TABLE I. 



A COMPARISON OF CHEMICAL ANALYSES OF CHICAGO AND UNIVERSITY OF ILLINOIS 



TAP WATER. 



Analysis of solids in parts per million, and gases in cubic centimeters per liter. 



Chicago Tap. U. of I. Tap. 



Potassium, K 6.0 2.6 



Sodium, Na 42.1 29.0 



Ammonium, NH4 0.04 2.3 



Magnesium, Mg 11.3 34.9 



Calcium, Ca 34-6 70.1 



Iron, Fe O;I5 i.o 



Aluminum, Al o.oo 1.3 



Silica, Si 3.3 18.9 



Nitrate, NOs 1.7 0.7 



Chlorine, Cl 12.0 3.5 



Lead, Pb o.oi o.oo 



Sulphuric acid, SOs 0.04 2.3 



Oxygen, 10.46 0.12 



Free carbon dioxide, COa 2.5 18.0 



Half bound CO2 (bicarbonates) 32.5 101.12 



Alice states that the change of water did not greatly affect 

 the rheotactic response of the isopods. At Illinois he kept the 



