aB2 REPORT OF THE COMMISSIONER OF FISHERIES. 
The surface water percolates through cavernous limestone. An aspi- 
rating effect is probably produced by the flow through fissures and 
narrow channels which have access to air spaces, and the air is sucked 
in and mingled with the down-flowing water, which it accompanies to 
the mouth of the spring. During the journey a diminution of the 
oxygen may occur from oxidation, which may reasonably explain the 
modified proportions of these gases. Though the mountainous region 
referred to abounds in springs, only a single other bearing air was 
found, and this a small one by the roadside. 
Air-bearing springs or wells of this character are to be distinguished 
from the ‘* breathing” or ‘‘ blowing” wells abundant in some sections, 
which alternately emit and suck in air from causes among which 
variations in the barometer are important. In Nebraska many wells 
having this remarkable peculiarity occur, and have been described by 
the United States Geological Survey (E. H. Barbour, 1899). The 
springs of supersaturation which deliver bubbles of air constantly are 
probably unrelated to breathing wells and, as far as known, pass the 
air in one direction only. 
The water of this Tennessee spring was apparently of excellent sani- 
tary quality—clear, cold (about 12° C.), slightly alkaline, and con- 
tained an excess of nitrogen, but not of oxygen. It was slowly fatal 
to fishes placed directly within the spring. Trout fry between 1 and 
2 inches in length were killed by it sometimes within a day or two, 
although some individuals would survive in it for weeks. On fish of 
this small size no internal gas within the vessels was in any case 
demonstrated with certainty. Neither were external symptoms usually 
present, but in the hatchery troughs supplied by the spring they were 
more frequent and sometimes extremely conspicuous, consisting of 
emphysema of the skin, either single cysts of gas, sometimes of rela- 
tively great size, smaller multiple cysts, or small blisters of gas, which 
usually had their seat upon the head or mucous membrane of the 
mouth cavity. Apparently the only inconvenience the fry experi- 
enced from these was a mechanical one. The buoyancy of the gas 
was often great enough to keep them constantly at the surface, and 
its unequal lateral distribution gave them a list to one side or the other. 
They did not appear to be materially weakened. 
When older trout, yearling rainbows 6 to 8 inches in length, were 
introduced into this spring, symptoms more closely resembling those 
at Woods Hole resulted. Death occurred with moderate symptoms of 
external gas, with gas free in the heart, though not abundant enough 
to cause distention, and with emboli of gas in the gill filaments. The 
susceptibility of species varied widely, and gold-fish were not affected 
during a trial of sixteen days, while other cyprinoids suecumbed almost 
as readily as the trout. These experiments with fishes in the spring 
were made in live boxes and were controlled by the same or similar 
boxes in the spring water after it had passed from the spring and been 
