The Microscope. 35 



far noticed I have recently observed on an undescribed species 

 of this favored genus, where the body is clothed by what seems 

 to be a mucilaginous investment crowded by slightly curved 

 bacilliform rods. This delicate coating is, in those individuals 

 most abundantly supplied, usually much deeper than the width 

 of the spaces between the transverse striations which also orna 

 ment the zooid, and the curvilinear, bacteria-like bodies are 

 densely distributed over the surface, appearing, when the Vor- 

 ticella is seen in optic section, like minute, solid, refractive 

 nodules scattered through this external film. These delicate 

 rods are extremely minute, measuring only t^wo of an inch in 

 length, and are visible only to a magnifying power of 500 diam- 

 eters obtained by a good objective, while the mucilaginous in- 

 vestment, if it is of that nature, is easily apparent with so low a 

 power as a T 4 o inch glass. The bacteriform bodies are usually 

 extremely abundant, being scattered, or arranged in irregularly 

 disposed clusters formed of several rods lying parallel to each 

 other. Occasionally the enclosing film is very scanty, the 

 curved rods then being correspondingly few and scattered, and 

 noticeable only at wide intervals on the surface, or along the 

 borders when the zooid is seen in optic section. On other indi- 

 viduals the film may be abundantly developed and irregular in 

 thickness. 



The body is quite changeable in shape while on the micro- 

 scope stage. I am inclined to believe that in its native waters, 

 with congenial surroundings it is not specially polymorphic. 

 My supposition is based upon the observation of a few individu- 

 als which remain unchanged to the end of prolonged examina- 

 tion. The rule is, however, that after a few moments, occasion- 

 ally even before the cover- glass can be applied and the 

 Vorticellae transferred to the stage, they lose their normal out- 

 line. Whatever they may be in their chosen haunts, they are 

 peculiarly sensitive to influences beneath the cover, speedily 

 showing evidence of being ill at ease. The body becomes vari- 

 ously distorted, the ciliary disk finally becoming much raised 

 and dome-like, the creature assuming a subglobose form, while 

 the striations grow gradually fainter, the external coating with 

 the bacilliform bodies remaining distinct almost until diffluence 

 takes place. The curious animalcules were quite accidentally 



