1901-2.] Dr Noel Patou on Dissolved Oxygen in Water. 145 
Observations on the Amount of Dissolved Oxygen in 
Water required by young Salmonidse. By D. Noel 
Paton, M.D., F.R.C.P.E. ( From the Laboratory of the Royal 
College of Physicians of Edinburgh .) 
(Finally adjusted for publication March 31, 1902.) 
That the absence of dissolved oxygen from water is fatal to fish 
is well shown by an observation of Wilh. Thorner ( Forschungs - 
berichte iiber Lebensmittel , 1897, 4, 172), on the condition of the 
water of the Hase at Osnabriick, where a great destruction of fish 
had occurred. Besides a complete absence of free oxygen in the 
water, nothing hurtful to fish could be detected. 
So far, no very satisfactory experiments have been recorded on 
the extent to which the dissolved oxygen in water must be 
diminished in order that it may act prejudicially on such active 
fish as the migratory salmonidse. 
Konig (Die Verunreiniguvg dev Gewasser, Bd. ii. p. 37, 1879) 
records some experiments, conducted by himself, in which fish — 
the kind of fish is not specified — were kept in water with 2*95 
and with 1*38 ccm. of oxygen per litre without being harmed. 
F. Hoppe-Seyler and Duncan (Ztscli.f. phys. cbem., Bd. 17, p. 
165, 1893) showed that trout kept for from 1 \ to 2J hours in 
water with from *98 to 1*710 cc. of oxygen per litre all showed 
marked symptoms of dyspnoea. Unfortunately these experiments 
were not continued for a longer period, and the observations on the 
influence of water containing greater and lesser quantities of oxygen 
were made upon tench, and the results cannot be applied to 
salmonoids. 
The present observations were made in connection with an 
investigation of the influence of estuarial pollution — and more 
especially the pollution of the Tyne Estuary — on salmon. 
Apparatus . — A Wolff’s bottle with three necks, holding 6000 
ccm., was fitted with three rubber stoppers. Through one a long 
thick tube projected downwards to near the bottom of the jar, and 
PROC. ROY. SOC. EDIN. — VOL. XXIV. 10 
