INFUSORIA 455 



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 exer- 

 cising its newly found power of locomotion. It is giddily 

 roving hither and thither, until the instinct of wandering 

 ceases, when it will soberly settle down, 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 in- 

 stead of longitudinal, the cleft occurring by constriction 

 across the middle of the vase; but this I have not seen. 

 In whatever direction it takes place, it is essential that the 

 oblong granular body, called the nucleus, which you see 

 in each vase, be divided, the cleft passing through the 

 middle of this substance, a portion of which is therefore 

 appropriated to each new-made animal. 



That the essential vitality of the creature resides in this 

 nucleus is shown by another and highly curious mode of 

 increase; namely, that which is effected by encystion. Let 

 us search the live-box carefully, for amid so great a pro- 

 fusion of Vorticelloe as we have on this Nitella, it will go 

 hard if we do not find some individuals in the encysted 

 stage. 



Look at this elegant object. It resembles a trumpet of 

 the clearest glass, with a rounded extremity, and with the 

 base affixed to the weed, from which it stands up erect. 

 Within the expanded part of the trumpet there is a turbid 

 mass, with a perfectly defined outline, from several points 

 of which proceed radiating pencils or tufts of long, straight, 

 stiff, elastic filaments, like threads of spun glass, varying 

 greatly in length, and each terminated by a little knob of 



