( 50 ) 
2. The method followed by Winkler *) to determine O t in water 
is sufficiently accurate to follow the 0 2 consumption of marine 
animals. In short it. comes to this: whilst the air is entirely shutoff 
a strongly alkaline JK solution and MnCl 2 is added to the liquid 
to be examined. The precipitate that is formed is, after settling, 
dissolved with HCl. The iodine that has been set free, titrated with 
7,„ norm, thiosulfate, yields with the aid of a simple formula (given 
by Winkler) the quantity of 0 , per Litre. 
That this method gives sufficiently accurate results, appears e. g, 
from the following experiment: 
ScyIlium canicular 
Weight temp. Duration 0 2 consumption 0 2 per hour Difference 
of the and KG. 
experiment 
24 and 25 gr. 12.13° 1 hour 2,55 c.c. 52.04 
0,78 
id. 13° 2 hours 5,02 „ 51,26 
In the following tables the 0 2 consumption is calculated per hour 
and M *. In order to convince myself, that the area of the animals 
may be said to be approximately proportional to the lK weight*, I 
defined the area of some sharks by the following method. 
The killed fish was dried in filter-paper and weighed. Then it 
was immersed in melted paraffine (50 n ), taken out and allowed to 
dry and cool, after which it was weighed anew. Now in different 
places of the-animal bits of paraffine were taken off (pieces as flat 
as possible), so that the skin was laid bare. These pieces were 
weighed and 
weight of 1 
I found: 
measured (with 
mm.* of the layer 
millimetre-paper) 
of paraffine was 
and the average 
determined. Thus 
Weight scyllium | 
Weight 
with paraffine 
Area | iKweight* 
9.9 
108.270 
11.65 
114 850 j 
1.65 
6.580 
i 0,36 
33 | 4.64 
'183 j 22 * 7 
With the small scyllium, therefore, ^weight 2 has to be multiplied 
by 8, with the large animals by 7, in order to get the area. 
3. The experiments with Scyllium cassicula were made m a 
sufficient qua ntity of water in diffuse daylight, the sharks lymg 
') Winkler, Berichte d. Deutschen Chem. Ges. XXI, 2 p. 2843. 
