51 
them. Moore and others (’05), in experiments with acids and alkalies 
found that the addition of a very little acid checked or stopped develop- 
ment in sea-urchin’s eggs, while much more alkali could be used without 
ill effects. This conclusion was confirmed by Whitley’s experiments with 
the eggs of the plaice, one of the flatfishes. After using several acids and 
several alkalies Whitley concluded (’05) that the deleterious effect on 
these eggs was due to hydrogen and hydroxyl ions. The earlier work of 
» Loeb (798,04) as well as that of Medes (718) showed the same thing. 
For the relative toxicities of salts and acids see Table III; note that 
HCI is 404 times as toxic as common salt. 
The addition of acid to water is accompanied by the liberation of 
CO,. This may be released from carbonates in quantities very harmful 
’ to fishes. Methyl-orange acidity is nearly always fatal to them (Marsh, 
07; Wells, ’15). In all such.cases the precise hydrogen ion concentration 
should be determined, but the concentration fatal to the various stages 
must not be neglected. Limestone is often used to neutralize acid, some- 
times to doubtful advantage. Table III shows the relative toxicity of a 
number of different compounds in distilled water. The table is incom- 
plete and based on the work of several authors. Further investigation is 
needed along this line. 
