A SUBAQUEOUS CITY. 143 



is revealed by which this motion is produced, in 

 a multitude of infinitely small semi-independent 

 organisms or ciliated cup-like cells, from the centre 

 of each of which is projected a comparatively 

 long whip -like cilium, which, by lashing the water 

 into ever-increasing velocity, eventually propels it 

 through all the chambers and passages and out into 

 the terminal mouth or oscule. These active agents 

 which line the walls of the passages and cham- 

 bers bear a striking resemblance to, if indeed they 

 are not exactly alike, certain classes of flagellate 

 monads which are found in associated groups as 

 distinct forms of infusorial life in great variety ; the 

 only apparent difference being that here they are 

 found with their cup-like bodies turned inwards, and 

 attached to a soft yielding protoplasmic substance, 

 instead of to a plant, in the open water. Whipping 

 the water, however, is not the only object accom- 

 plished by these ciliated zooids. As the current is 

 passed on from one to another, the nutrient matter 

 held by it in solution is absorbed by these active 

 workers, and feeds them, while the surplus passes 

 on to their nearest neighbours, to whom they are 

 attached by a physical bond. Strangely enough, 



