E. D. Clark and L. H. Almy 493 
Iodine Number.—The iodine absorption number was determined by the 
Hanus Method? on 0.1 to 0.2 gm. samples using 25 cc. of iodine solution. 
Saponification Number.—Approximately 1.5 gm. of oil were saponified 
in the usual manner? with 25 cc. of alcoholic potash for this determination. 
Acid Value.—1 gm. of oil was dissolved in 50 cc. of a neutral mixture 
of three parts ethyl ether and seven parts 95 per cent alcohol, and titrated 
with 0.1 N sodium hydroxide solution, using 0.5 ce. of 0.5 per cent alco- 
holic phenolphthalein solution as indicator. The addition of alkali was 
continued until one drop produced a pink color which persisted at least 1 
minute. The result was calculated to mg. of potassium hydroxide required 
to neutralize the free fatty acids of 1 gm. of the oil. 
Tabulation of Analyses. 
It was not possible to obtain samples of each species at varying 
seasons, hence of some fish but one analysis appears in the tables. 
It is believed that, aside from their interest in the light of seasonal 
variation, such analytical data are of value from the composi- 
tion viewpoint alone. Tables III, IV, V, and VI record the re- 
sults obtained. The values given are in all cases the average of 
two or more concordant determinations. 
DISCUSSION. 
Biological Stgnificance of the Fat Content. 
Many sea fish travel in schools, or migrate, in response to stim- 
uli of which we are still ignorant and to regions often unknown at 
definite times of the year. They feed on small animal organ- 
isms, lower plant forms, or other fish, depending upon the habits 
of the various species. In the contest: with fellow members of 
the school, certain fish will fare better in feeding than the less 
strong and active ones. This may account for the fact that fish 
of the same size from. the same school occasionally vary consid- 
erably in fat content. ‘The fish in Table VII were taken from 
the same school and show an exceptional degree of variation in 
this respect. 
2 Hanus, J., Die Anwendung von Jodmonobromid bei der Analyse von 
Fetten und Oelen, Z. Untersuch. Nahrungs.-Genussmittel, 1901, iv, 913. 
3 Official and provisional methods of analysis, U. S. Dept. Agric., Bureau 
of Chemistry, Bull. 107 (rev.), 1909, 136. 
