ANIMALS AND PLANTS. 



and careful management of the light. In the centre of 

 the pear-shaped body a clear round space could occa- 

 sionally be discerned, but not always ; and careful watch- 

 ing showed that this clear vacuity appeared gradually, 

 and then shut up and disappeared suddenly, at regular 

 intervals. Such a structure is of common occurrence 

 among the lowest plants and animals, and is known as 

 a contractile vacuole. 



The little creature thus described sometimes propelled 

 itself with great activity, with a curious rolling motion, 

 by the lashing of the front cilium, while the second 

 cilium trailed behind; sometimes it anchored itself by 

 the hinder cilium and was spun round by the working 

 of the other, its motions resembling those of an anchor 

 buoy in a heavy sea. Sometimes, when two were in full 

 career towards one another, each would appear dexter- 

 ously to get out of the other's way ; sometimes a crowd 

 would assemble and jostle one another, with as much 

 semblance of individual effort as a spectator on the 

 Grands Mulets might observe with a telescope among the 

 specks representing men in the valley of Charnounix. 



The spectacle, though always surprising, was not new 

 to me. So my reply to the question put to me was, 

 that these organisms were what biologists call Monads, 

 and though they might be animals, it was also possible 

 that they might, like the Bacteria, be plants. My friend 

 received my verdict with an expression which showed a 

 Bad want of respect for authority. He would as soon 

 believe that a sheep was a plant. Naturally piqued by 



