354 REPORT OF THE COMMISSIONER OF FISHERIES. 
The time required for a fatal result depends primarily on the degree 
of excess. Death has been observed within three hours after intro- 
duction of a healthy fish into the abnormal water, but in this case the 
exact excess is unknown, and there was no autopsy. At 10° C. and 
an excess of 6c. c. of nitrogen and 2 c. c. of oxygen per liter, a hake 
was killed at the end of 8 hours, and embolic gas under pressure in 
the heart was observed immediately after death. Ten hours fre- 
quently suffices fer this result. Species differ in susceptibility. 
Identity of gas in the blood vessels, external vesicles, and water.— 
Some relation of identity or source between the several gases within 
the blood vessels, in the external blebs, and that which separates 
directly from the water upon the fishes is at once inferred as prob- 
able, and the gas of all the lesions would seem to be derived from the 
water. The following four samples were determined by the United 
States Bureau of Chemistry, the first three collected in February. 
The merely adherent bubbles which formed on the exterior of the 
fishes had the following composition: 
Per cent. 
Garbonsdiosmid) <2 fa. 2G sas San eae Se eee aie ne ee eae me 1. 03 
Osyigemis olf se Nese Se th seetine asses Melee eee Nes re ee eee 17.58 
INDO els us tinct eS SSSR coe het See ae eee 81. 39 
A sample precipitated upon blocks of wood, no fishes being in the 
water, consisted of: 
Per cent. 
Carbon. diomid: 2-522. = 256 Sets aoe ome eee cee eee 0.58 
Oxye@enial A 2552s w soe eae ee ee en eee eee ee ae nEenEEY 
INVORON SS 2. L Seek ec Sol ck ce ocicln crs tmeieelen iia soc e eee mere eee 76. 55 
The difference between the carbon dioxid and oxygen in these two 
samples should be referred to the respiration of the fishes, present in 
the first case and absent in the second. The gas from the large ves- 
icles on the belly of the small sculpin (J/yowocephalus aeneus) was as 
follows: 
Per cent. 
Carbon. diosa 52: Bee ro es ES hs Se a eee 3. 78 
Omyoenids 528 eh ao Be as eee sean eee eee ete eee eae 18. 09 
INDtROPEN 2° Se ete seed Soe ee ae ees eee ie yee eee 78.13 
In this the oxygen is diminished and the carbon dioxid increased by 
oxidation of organic matter in the tissues. Methane, hydrogen, or 
carbon monoxid were not present in any of these samples. 
A sample collected in September from the water alone showed: 
Per cent. 
Carbon. dioxid=i 223i 5 32. ee eee ee eee ee 0.4 
Omypen. 62:41 35 eed Uk See ee 2 ee eee ae ae 
Nitreren: ..2- 45, 22.0.5 te cp eine ae ee eee ee see a 79.0 
The gas is evidently nothing more than the constituents of air, the 
proportions varying more or less from those of the atmosphere. 
