8 Obacrvatiojis on the Natural History 



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 

 temperature, 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 prolei have been kept in a small ves- 

 sel of water of the temperature from 43° to 45°,5, and have lived 

 very well, although the water has not been once changed, 



In the ordinary act of changing the water iu which the ani- 

 Hials 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 ; ibr iu winter, when the temperature is from 45° to 

 48°, if the proteus be placed in obscurity, and left perfectly 

 quiet, the gills are always j5allid, 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 ahvays 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 i» 

 much disturbed, expels bubbles of air through the branchial 

 apertures, moves rapidly in the vessel, and attempts to escape : 

 the gills become very red, and are sp 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 7T'- 



