INFUSOEIA. 463 



they are at all times perfectly smooth and rounded ; at 

 length two -vases appear, side by side, where a few 

 minutes before there had been bvit one. 



One of these is destined to be ultimately thrown 

 off, while the other retains sole possession of the stalk. 

 You soon see which it is that is going to emigrate : for 

 though the two are alike in size, the roving one early 

 closes the mouth of the vase, becoming smooth and 

 globular there, never to open again. The cilia, now 

 therefore become useless, disappear by absorption ; but 

 meanwhile a new circle of these organs are developed 

 around the basal extremity of the vase, and these, 

 every instant becoming more vigorous in their motions, 

 sway the little globe about on its point of attachment. 

 At length the connexion yields, breaks, and the ani- 

 malcule shoots away, rowed by its hundred oars, to 

 find a new abode, and to found a new colony. 



Here and there you see shooting through the group, 

 with a rapid gliding movement, an oblong clear body. 

 This is one of the vases, formed by self-division, and 

 exercising its newly found power of locomotion. It is 

 giddily roving hither and thither, until the instinct of 

 wandering ceases, when it will soberly settle do-^vn, 

 affix itself by the-point which was formerly its mouth, 

 whence a new stalk will gradually grow, and opening 

 a new mouth in the midst of the new crown of cilia. 



I believe that the division is sometimes transverse 

 instead of longitudinal, the cleft occurring by constric- 

 tion across the middle of the vase ; but this I have not 

 seen. In whatever direction it takes place, it is essen- 

 tial that the oblong granular body, called the nucleus, 

 which you see in each vase, be divided, the cleft pass- 

 ing through the middle of this substance, a portion 



