SEA-FISHERIES LABORATORY. 17 
paper to remove any surplus moisture present. It was next 
transferred to a dried weighed filter thimble and weighed. The 
nett weight of the moist Temora was found to be 2-688 grammes. 
The thimble filter and Copepoda were then dried to a constant 
weight in a water bath which was kept boiling. The nett weight 
of dry Temora was 0-925 gramme. The oil was extracted by 
means of the Soxhlet apparatus and carbon tetrachloride into 
a weighed flask. From the results obtained it was calculated 
that 100 grammes of dry Temora substance contained 2-47 
| grammes of oil. The oil while warm wasa pale yellow liquid, but 
on completely cooling it became a solid somewhat crystalline 
“mass. The quantity of Temora used was of course much too 
small for an accurate investigation, which should have been 
regarded as approximate. It is very rarely that sufficiently 
large samples of a single species of Copepoda are found in the 
Irish Sea to enable one to determine the amount of oil. The 
richness of the plankton plays a very important part in a 
successful herring fishery. No doubt much of the fat which 
' makes the Manx summer herring so valuable is derived from 
the Copepoda captured by the fish as it swims through the 
a 
= for comparison. The result must therefore only be 
| Ill. Foop or Port Erin HErRRinaG. 
j In the report for 1916 (page 9) I gave the results of the 
" examination of herring stomachs from a sample of fish landed 
q at Port Erin on July 5th, 1916. Professor Herdman sent me 
another stomach from a sample of herring landed at Port Krin 
on July 31st, 1917. This stomach was carefully opened up. 
‘The contents were mixed with a little water and transferred 
to a measuring jar. After allowing the solid matter to settle 
i 
_ for some time its height was read off and was found to measure 
_ 5 cubic centimetres. A detailed examination was then made 
