384 
TABLE IV 
Showing the relation of hydrogen ions (CO, added) and oxygen to the 
survival of fishes. Taken from the work of authors indicated. 
3 3 Survival 
5 Wt. in | Survival O., ¢. ¢. 
Author , Species : pH oe time 
gm, in min. per liter per gram 
p +#2.0 22 6.6* .1-.15 10.9 
Wells ......... AUPE ES Alf 220 46 7.0% | .1-.15 | 20.2 
DANS +2.0 140 7.7% Jab e225 
Notropis 6-.8 15 6.6* .1-.15 25 
SSSI SE cornutus 6-.8 | 195 7.8% | .1-.15 | 246 
Coregonus .|......... 148 6.3 sal 
CULPCTT OPIS. | a atve oe eres 225 SRO wk 
Hal ees BA: Son ll eee 240 6.3 ey 
hatching a0 see es ee 300 9.0 aa 
* pH calculated. 
Powers (’22) has shown that marine fishes require more O, at high 
hydrogen ion concentrations. Thus, in general, the unfavorable effect 
attributed to low oxygen is partly due to the pH which accompanies it, 
and this depends largely on the amount of carbonates in the water. The 
hydrogen ion concentrations which many workers have considered that 
they were using when acid was added to distilled water have not been 
attained because of the carbonates present. It has been customary to 
regard distilled water as essentially free from salts, especially carbonates. 
Wells (715) stated that he conducted experiments in distilled water which 
contained no salts. Later he showed that it had a conductivity of 600 
10—* which suggests +.0005 N solution of carbonates, which is now 
known to be approximately the carbonate content of distilled water 
from the source where he obtained his. He did not have anything like 
the H ion concentration he assumed, either in the killing or gradient 
experiments. If no salt had been present the pH of his ‘‘.000075 
H.SO,” would have been between 4.0 and 5.0, which would have 
quickly killed the fish. An unfortunate loose statement (715, p. 253) 
that “fresh-water fishes * * * cannot live normally in neutral [he 
used the term neutrality for the turning point of phenolphthalein, 
which as he used it is pH 8.0] or alkaline water caused misunderstand- 
ing. In fact, most fresh waters of the Eastern United States are alka- 
line, and most fresh-water animals live in such waters. The facts 
were that in water with pH 8.0+ the particular species with which 
he worked became sluggish and were unsuitable for behavior studies, 
or died in higher hydroxyl ion concentrations. The concentrations 
in which he killed the fish were probably only titrated with standard 
acid, and therefore it is not possible to state what the pH may have 
been. 
