242 MORRIS M. WELLS. 



water in 2 days, but when this same liter of water was divided 

 into two parts and a 3-gm. blue-gill placed in each part, both 

 fishes were normal at the end of a month. In Table IV. is given 

 a summary of a number of experiments performed with blue-gills 

 in once-distilled water. 



TABLE IV. 



SHOWING THE RESISTANCE OF SMALL BLUE-GILLS (3-5 GRAMS) TO DISTILLED 



WATER THAT is BARELY ACID WITH COz. 

 Conditions of Expt. Fish Placed in, Resistance of Fishes. 



1. Freshly distilled water Normal after 5 days; expt. discont. 



2. Boiled distilled water Normal after 5 days; expt. discont. 



3. Distilled water plus Na2COs to make 



neutral Normal after 2 days. Water acid 



again. 

 Added a little NaHCO 3 to (3) to 



keep neutral Dead on loth day. 



4. In dist. water as in (i) Normal after 30 days. 



Table IV. shows that the once-distilled water is not greatly 

 if at all toxic to the blue-gills, but experiment 3 shows that these 

 fishes cannot live in the water if it is slightly alkaline. This 

 same distilled water is rapidly toxic to the crappies and sun- 

 fishes, however, as was shown in an experiment already described 

 and in those which follow. This lack of resistance of the sun- 

 fishes in particular is a complete reversal of the ordinary specific 

 resistance of these fishes as compared with the blue-gills, for 

 in carbon monoxide, ethylene, sulphur dioxide, etc., the sun- 

 fishes are much more resistant than are the blue-gills. 



On January 30, a liter of water (once-distilled) was made 

 .00005 N acid with H 2 SO 4 and another liter left as it came from 

 the still. An 8-gram crappie was placed in each jar. The 

 fish in the pure distilled water was dead in 12 hrs. while the one 

 in the distilled water made acid, lived for 65 hrs. Several other 

 experiments of this sort gave similar results, showing that the 

 crappies cannot live in the neutral distilled water when it is 

 pure, as well as they can when it is made slightly acid. It is 

 very probable that sightly higher concentrations of acid than 

 those used would have prolonged the lives of these fishes even 

 more successfully than the .00005 N DUt as the stock of fishes 

 was running low, these experiments were reserved for another 

 time. 



