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64 ORGANIZA TION OF THE INFUSORIA.approaches in many instances the one last mentioned, while in others itexhibits widely distinct features. Like the preceding,it is connected withthe phenomena of reproduction, but the encysted animalcule multipliesitself not merely by the process of binary fission, but by the subdivision ofthe encapsuled mass into a greater or less number of spore-like bodieswhich, after a more or less prolonged quiescent state, developto theparent form. This type of encystation may be most appropriatelydenominated "sporular encystment," and the cyst or capsule secretedin such instances, a " sporocyst." Details of this special mode of multiplicationare given in the section devoted to the subject of reproduction,and it isonly requisite here to indicate one important point in which suchsporular encystment departs widely from both of the preceding kinds.In each of these latter the cyst or capsule producedis the product of aprimarily single and independent animalcule, but in the one now alludedto itvery frequently, though not invariably happens, that such a cyst isthe product of two primarily amalgamated or conjugated zooids.manyIn certaincases, even, as, for example, Heteromita uncinata, as as three or fourconjugated animalcules build up the characteristic sporocyst. This specialsporular form of encystment is, with but few exceptions, limited to theFlagellate class of the Infusoria.Locomotive and Prehensile Appendages.All of the variously modified appendages possessed by the severalorders of the Infusoria, used indifferently for the purposes of locomotion orprehension, are to be regarded as mere extensions of the body-protoplasm ;sometimes, as in most Flagellata, they are produced directly from the externalsurface of the ectoplasm, and in others, as the Ciliata, from the deeperor cortical layer of that element. In certain Tentaculifera the characteristictentacle-like appendages would seem to originate in close proximity to thecentral or endoplasmic region. With the exception of the organs lastmentioned, which would appear to most nearly represent specialized modificationsof the pseudopodia of the Radiolaria, the transition from one tothe other of the several types of appendages borne is most distinct andgradual. In this manner, flagella can be characterized only as isolated andmore or less elongate cilia while the divers forms of;setse, styles, and uncinipossessed most abundantly by the Ciliate section of the series, can be regardedas variations only, in separate directions, of similar simple cilia. Viewedfrom an independent standpoint, and as is requisite for the purposes oftechnical diagnosis, the term of " cilia " may be conveniently restricted tosuch short, slender, vibratile appendages as constitute the ordinary locomotiveorgans of a Paramecium, or the more or less convolute adoral ciliarywreath of a Vorticella. With the name of "setae" are to be associated theslender, hair- like, more or less flexible but non-vibratile appendages thatclothe the entire body of a Pleuronema, that are developed girdle-wise, andfulfil a special leaping function in the genus Halteria, or that in an isolated