ZOOL.-VOL. III.] STEVENS-CILIATE INFUSORIA. 9 



from a branching base at the center of the attachment disc 

 and extends diagonally through the neck to the beginning 

 of the oral band, where it gives off a branch to each end of 

 each basal band. The first branches given off are coarse 

 and oblique, the later ones fine and nearly perpendicular 

 to the basal fibre (figs. 4, 17,/'. and 74). 



This stout neck fibre with its oral prolongation and 

 branches is somewhat anisotropic, fibrous, and contractile. 

 The only clearly differentiating stain found for it is iron- 

 hsematoxylin ; second to this was Mayer's picro-carmine, 

 the material being left in the stain for forty-eight hours. 

 In macerations, the fibre with its various branches is the 

 most resistant part of the body. Potassium bichromate (one 

 to three per cent.) will in a few seconds, aided by slight 

 tapping on the cover-glass, dissolve away the alveolar ento- 

 plasm and the pelHcula, leaving the inner layers of the 

 attachment disc with cilia, the neck fibres and the oral 

 band with ciha, the skeleton of the animal, as it were 

 (fig. 17). Similar results were attained with pepsin and 

 peptone solutions, one-tenth per cent, formalin, and even 

 with fresh water. The neck fibre is faintly visible in life, 

 and is plainly seen in any macerating or fixing fluid be- 

 fore the cilia of the attachment disc and pharynx cease 

 to vibrate. These facts clearly demonstrate that the fibre 

 and its divisions so plainly shown in iron-h^matoxyhn 

 stained sections are not artifacts. 



Johnson (1893) describes a fibre (first mentioned by 

 Brauer (1885) ) to which he ascribes a contractile or per- 

 haps a coordinating function, connecting the roots of the 

 oral membranell^ of Stentor. This structure is probably 

 homologous with that of Licnophora but less complex. 

 Schuberg (1886) describes a "Peristomband" and "Quer- 

 band" in Bursaria truncatella as homogeneous (Biitschli 

 says fibrous), and of ectoplasmic origin, while the fibres of 

 Stentor and Licnofhora are fibrous and entoplasmic. 



The neck or stalk of the infusorian is flattened dorso- 

 ventrally, especially when extended. In contraction it is 

 crossed by transverse wrinkles and deep furrows, both 



