LIFE, IN ITS LOWER FORMS. 



marked (d). As the two divisions become more separate, 

 each assumes an oval form, united at length to its fellow- 

 only at the base (e). At this time the motion of the cilia 

 is plainly visible, forming a circle in each within the 

 body, near the summit. As the process goes on, the con- 

 nexion between the two is reduced to a mere point, and 

 they become capable of separate motion, so far as to 

 diverge and look in opposite directions ; the point of 

 union being the common stem (/). At this stage we 

 may observe that the bell which is destined to remain is 

 open at the top, within which the ciliary waves are chas- 

 ing each other in continuous wheels, the other bell being 

 closed at the summit. 



But on the latter, which is ultimately to be thrown off, 

 a new and highly interesting phenomenon appears. The 

 cilia, which before the division had juayed around the 

 mouth, have become obliterated, probably by absorption ; 

 the orifice at that extremity has closed up permanently, 

 for this is to be the base of the new animal ; and a new 

 bell-mouth and a new wheel of cilia, are to be formed at 

 the opposite end, which at present remains attached to the 

 common stem. The first indication we can detect of this 

 new formation is a very slight motion in the water, a little 

 quivering around what we must as yet call the basal 

 part. Presently there appear waved hairs, which seem 

 very flexible, and the motion of which resembles that of a 

 fringe of loose silk moved through water, an action very 

 different from the regular waves of perfect cilia. These 

 waving hairs increase rapidly in length, and in the vigour 

 and rapidity of their undulations, which gradually become 

 decidedly rotatory, producing at length strong currents in 



