138 PARTIAL WATEE TRESPASSERS. 



way into its fur had interfered with the set of the 

 hairs, and had allowed the air to escape, and conse- 

 quently the water to get in. Take, again, the familiar 

 example of a sponge. Sink it below the water with- 

 out pressing it ; let it remain for a few minutes, and 

 then remove it. Scarcely a drop of water will have 

 penetrated to its interior. Bubbles of air will be seen 

 at the mouth of every aperture, and will have acted as 

 effectual barriers to the water. Sink it again for half 

 a second, but squeeze it at the time, and then loosen 

 it. On removing the sponge it will be found filled 

 with water, the air having been expelled by the 

 pressure. 



Now, every one who has watched the gambols of 

 the Water shrew in a stream, has been struck with the 

 beauty of its appearance when diving. It seems to be 

 enveloped in a suit of silver spangles, and this appear- 

 ance is due to the innumerable air bubbles which are 

 entangled among its hairs, and which glitter just like 

 those of the sunken sponge. So firmly are they held 

 among the hairs that the rapid movements of the 

 animal through the water do not dislodge them ; and 

 they alter its appearance so completely, that when 

 the Water shrew emerges and goes pattering along the 

 bank, it is hardly to be recognized as the same 

 creature which was but a moment ago gliding beneath 

 the water ; the velvet-black of its dry coat contrast- 

 ing curiously with the silvery suit which it wears 

 while submerged. 



It has already been mentioned that the sense of 

 hearing is in these animals very acute. That of sight 

 appears to be rather dull, or perhaps it is incapable 



