224 
BULLETIN OF THE BUREAU OF FISHERIES. 
The fractionates of the creosote show a steady decrease in toxicity with rise of 
boiling point. 
That 100 cc. of sea water did not by any means exhaust the toxic substances 
in 10 grams of oil was shown well by toxicity determinations on extracts made 
from smaller quantities of the oils. In experiments 30, 34, and 35 (fig. 2) the 
toxicities, respectively, of 10:100, 5:100, and 2.5:100 extracts of Fraction I are 
compared. The toxicity of this fraction does not diminish in proportion to the 
weight of oil extracted. The same statement holds for creosote (experiments 39, 
40, and 41). This is brought out more strikingly by comparing a 5:100 extract of 
Fraction II (experiment 34) with a 10:100 extract after dilution with an equal 
volume of sea water (experiment 36); or by comparing a 2.5:100 extract (experi- 
ment 35) with a 10:100 extract after dilution with 3 volumes of sea water (experi- 
ment 37). 
Fraction II was practically solid with naphthalene at room temperature, yet 
a 10:100 extract of the mixed fraction (experiment 23) was not markedly less toxic 
than a 10:100 extract of the liquid portion only (experiment 29). But dilution 
of a 10:100 extract of the mixed fraction with an equal volume of sea water caused 
a sharp lowering of toxicity (experiment 38). 
A 10:100 extract of the tarry residue of Fraction I, after the latter had been 
made to lose 80 per cent of its weight by spontaneous volatilization, still showed a 
definite toxicity (experiment 59). 
EMULSIONS. 
These were tried out to determine whether dispersions containing all the con- 
stituents of the several oils would yield toxicity data of the same order as those 
obtained with the extracts. 
The method of preparation of the emulsions was as follows: Ten grams of the 
creosote preparation were triturated with enough finely powdered acacia to make a 
friable powder. This was transferred to a 250 cc. bottle and sea water added 
gradually, with vigorous shaking, until a total of 100 cc. was obtained. The resulting 
mixture was a fairly viscous, apparently homogeneous, liquid. Toxicity experi- 
ments with the emulsions were then made in the same manner as the experiments 
with aqueous extracts. 
In the lower two rows of Figure 1 the results with the emulsions have been 
arranged in the order of diminishing toxicities as follows: Experiments 54 (Frac- 
tion I), 53 (Fraction II), 61 (creosote), 60 (Fraction III), 66 (Fraction IV), 73 
(Fraction V). The sequence here duplicates that seen with the aqueous extracts. 
It will be seen that a 10:100 emulsion of any one of these oils is more toxic 
than a 10:100 sea-water extract. This is to be expected, since the minute droplets 
of oil in the emulsion will tend to keep the surrounding water saturated with their 
constituents. 
LIGHT OILS. 
The light oils tested were benzol, toluol, and a mixture of the isomeric xylols. 
In earlier experiments it had been observed that Limnoria would live for days 
when superficially dried and immersed in a nontoxic oil such as medicinal petroleum 
