OF THE PEOTOZOA. CILIATA. 297 



portion of the body is much elongated, and supports a ciliated process, when 

 fully extended, straight and of a sword-shaped figure, fringed along one side 

 and at the end with cilia (XXIX. 5) ; but when in active vibration and t^virl- 

 ing the animalcide onward in a spii'al manner, the greater part of this ciliated 

 process becomes ciuwed like a sickle (XXIX. 6). 



Another bizarre form of ciHary apparatus is exhibited by the genus Lagotia, 

 described by Dr. Strethill Wright as a member of the family Ojplirydina. 

 The head of this animal protrudes a pair of horn-like divergent processes, 

 fringed around with cilia, flat or folded longitudinally, and straight or recurved 

 at the extremities. These ciliated appendages, together with the elongated 

 body they surmount, enjoy a very great latitude of motion by alternate con- 

 traction and extension, and by curving and tmsting in different directions. 

 The mouth lies in the angle between the processes. The whole being may be 

 said to stand in a position, mth regard to the rest of the VorticelUna and 

 Ophrydina, similar to that of Stephanoceros to the other Rotatoria. 



INTEENAL OKaANIZATION OF THE CILIATED PROTOZOA. 



STJBTEGUMEIfTARY LAYER; CHLOROPHYLL; ThREAD-CELLS ; MtJSCLES. Sub- 



jacent to the cuticle is a layer of granules and smaU globules, which is 

 often spoken of as a second lamina, just as the cutis vera in higher animals 

 is of the cuticle. Its thickness is considerable ; it is hyaline, and more con- 

 sistent than the contents, and, although homogeneous itself, contains a multi- 

 tude of granules, and, at least in several genera {e. g. Paramecium, Oplirydium, 

 Nassida), numerous chlorophyll-vesicles, often so thickly disposed as to impart 

 a Hghter or deeper green colom- to the animal (XXIX. 28). In young, and 

 also in very old, specimens this coloui^iag-matter is wanting, and only colom^- 

 less granules with a dark outline, resembhng small fat-particles, present. 



In Mr. Carter's phi^aseology this cortical lamina bears the name of the 

 " diaphane," and is said to lie beneath the ^' pellicula," but not to be secreted 

 from it. The j)roperty of contractility resides in it, whence it becomes so 

 far analogous to the muscle or flesh of animals, that to it the term ' sarcode ' 

 may most appropriately be apjolied. Dujardin, however, who first employed 

 this term, did so to designate the entire component organic mass of Protozoa ; 

 but as later observers seem to make out the presence of a somewhat dis- 

 similar substance, of a much looser and more mucilaginous consistence, sur- 

 rounded by the contractile layer in question — in other words, within the 

 so-called abdominal cavity — we feel quite justified in limiting its signification 

 as we have done. 



That the cortical layer alone is contractile, Lachmann considers {A. N. H. 

 1857, xix. p. 126) to be shown by the fact, that '' in torn Infusoria fragments 

 of it not imfrequently contract, whilst the internal mass, the * chyme,' which 

 flows out, never does so." Its contractions eifect the various alterations in 

 the figure of animalcules, whilst by its greater consistence compared with the 

 abdominal contents, and its fixity as a layer subjacent to the cuticle, it affords 

 a surface, and even a nidus, for the attachment of the nucleus and contractile 

 vesicle, which it therefore serves to retain in situ, not-withstanding the 

 opposing forces of the circulatory current and of particles of food propelled 

 against them (see section on Cu'culation). To demonstrate this quiescent 

 cortical lamina and the inner moving stratum also, chromic acid affords the 

 most eff'ective means. 



The cavity enclosed by the cuticle and subjacent cortical lamina is occupied 

 by an almost fluid matter, for which the term " abdominal mucus " is suggested 

 by Carter, and that of '' chjTue " by Lachmann, the former we esteem the 

 better, although it imperfectly represents the actual state of things ; for in 



