Ophrydhia.'] INFlTSOniAL animalctties. 647 



the former process more commonly (P. 22, f. 10, 11.) The develop- 

 ment of the bud takes place from the base of the parent, and within 

 its sheath. The young being, produced by either process, is furnished, 

 as in Vorticella, with a posterior wreath of cilia, whilst it is endowed 

 with free locomotion (P. 22, f. 11.) It frequently happens, as re- 

 presented in the last quoted figure, that the new being formed 

 assumes a contracted ovoid form, with its frontal wreath retracted. 

 Upon the appearance of the posterior whorl of cilia, and aided by 

 their movements, the young animal loosens itself and escapes fi-om 

 its parent case, and s\\'ims freely away, elongating itself, it may be, 

 if previously contracted, and assuming finally all the characters of a 

 perfect Vagiiiicola, by developing around it its own special sheath. 



On the other hand, the contracted individual may become actually 

 encased within its integument, in other words, encysted, and pass 

 through a peculiar cycle of changes, by assuming all the characters 

 of an Acineta. In the encysting process, the animal sinks towards 

 the bottom of the case produced around it, and thus drags on its 

 anterior part, bringing the sides of its original opening into approxi- 

 mation. In effecting this closure, a substance appears to be thrown 

 out anteriorly, which, by reason of its acting as the medium for 

 closing the case and connecting this with the contained body. Dr. 

 Stein designates the * binding- substance.' This substance appears in 

 the form of plaits or folds crossing each other (P. 22, f. 12, 13.) 

 The animal is now seen as a motionless granular mass, not entirely 

 filling its case, without trace of its mouth and fi"ontal wreath, but 

 still possessing a contractile vesicle, or a nucleus, or both. From 

 between each of the angles of the binding substance, filiform fibres 

 proceed, vnth rounded knobs at their apices, flexible, and capable of 

 elongation or retraction. These fibres. Stein believes, are of the 

 same nature as the variable processes of Amceha and Arcellma; they 

 move fi'eely about, crossing one another, and often entangKng small 

 Infusoria, or other floating particles, which they draw towards the 

 surface of the Acineta. However, neither such captured particles, 

 nor any others, are ever seen to enter within the cyst ; nor are any 

 food globules to be detected within the body ; for there is no mouth, 

 all commimication with the exterior being cut off by the outer tough 

 case or integument, and also by the subjacent binding-substance. It 



