of the Proteus Anguinus. , 405 
gently flowing. The authors enclosed a proteus in a box, per- 
forated with holes, which was then sunk in a large lake, and 
kept for three months and a half beneath the surface. At the 
end of this time, on examining the box, the animal was found 
extremely lively, which clearly shewed, that submersion in wa- 
ter for so long a period had in no way injured its vital economy. 
The temperature of the water, through the whole period,, va- 
ried little from 66°. But if the temperature be under 54°, say 
from 45° to 48°, it is of little consequence to the proteus whether 
the water be much or little, fresh or stagnant, since at so low a 
temperatu^, he remains always as if immoveable at the bottom 
of the vessel, and never comes to the surface to inspire air. For 
four months together, two protei have been kept in a small ves- 
sel of water nf the temperature from 43° to 45°.5, and have li- 
ved very well, although the water has not been once changed. 
In the ordinary act of changing the water in which the ani- 
mals are kept, if the fresh water be of a lower; temperature than 
that which it replaces, the proteus becomes somewhat pale, and 
the gills, previously of a vermilion hue, turn pale, and collapse 
in an instant. This observation can, however, be made only in 
summer ; for in winter, when the temperature is from 45° . to 
48°, if the proteus be placed in obscurity, and left perfectly 
quiet, the gills are always pallid, collapsed, and very small ; 
and, should he be even molested, they do not appear so branch- 
ed or red, as we see them when in a temperature varying from 
68° to 72" ; in which case, if the animal be at the same time 
well nourished, the gills are always in the erected state repre- 
sented in the drawing. Should the water be raised successively 
to 77°, 88°, or 104°, it is observed, that at 88° the animal is 
much disturbed, expels bubbles of air through the branchial 
apertures, moves rapidly in the vessel, and attempts to escape t 
the gills become very red, and are so turgid with blood, that 
their points are turned upwards. And when the temperature is 
^carried to 104°, the distress of the proteus is very great : he 
makes such movements and contortions of the body as if about 
to die, but which soon cease, if the temperature be reduced to its 
proper point. Hence it seems, that the proteus is not able to 
live long in a temperature much above 77°. 
