INFUSOniAl ANIMAICTTIES, 73 



fixed Rotatoria to withdraw themselves within the investing sheath, 

 or tube, within which they live, after having previously extended 

 themselves beyond it. 



Dr. Dobie, in his account of the species of Flosculwria, describes 

 their " ciHa as of two kinds ; one of the usual short vibratile kind, 

 covering the interior of the alimentary tube ; the other, extremely 

 long and filiform, of uniform thickness and not vibratile under ordi- 

 nary circumstances. They are slowly moved, and spread out by the 

 contractile substance of the lobes of the rotatory organ." He adds, 

 " when a solution of caustic potash is brought in contact with the 

 filiform cilia, a most violent vibratile action immediately commences) 

 and continues till the whole bundle is completely disorganized. 

 Violent mechanical stimulation seems to have a similar efiect, though 

 in a less degree." 



The form of cilia, described by Dr. Dobie, on the rotary apparatus 

 of Floseularia is exceptional, the general kind, imparting the sur- 

 prising locomotive power of the organ, being short and actively 

 vibratile. (See Wood Engraving, Part III.) 



Dr. Dobie found "immediately below the integument of Floscu- 

 laria cornuta, groups and lines of very small granules, continually in 

 a state of rapid molecular motion, in appearance, exactly resembling 

 the molecules in the cusps of Clostermm. Besides the molecular, 

 they are subject to another motion, for occasionally they move from 

 one part of the surface to another, in currents not very distinct or 

 persistent, and in no definite direction. He has seen them running 

 in lines down the tail, and collecting in groups. This flowing move- 

 ment occurs chiefly during the contractions and relaxations of the 

 entire animal. He thinks it probable that these granules are con- 

 nected with the nutrition of the animal, and analogous to the free 

 floating corpuscles of the Tardigrada, described by M. Doyere." 

 (Ann. Nat. Hist. 1848, p. 233.) 



Section XXI. — Of the Digestive System of Rotatoria. — The 

 Rotatoria possess a distinct and undoubted alimentary canal, evident 

 as a tube traversing their interior, from the mouth to the posterior 

 outlet, having a certain definite position, and absent in only a few 

 instances. 



Food is drawn into the mouth, by means of the vortex, occasioned 



