( ^45 ) 

 ORIGINAL COMMUNICATIONS. 



Notes on the Structure of Oscillatori^e, with a Description 

 of a New Species, possessing a most remarkable Locomotive 

 Power, iwt Cilia. By Dr. F. d'Alquex. (Plate XIV.) 



The study of the structure of the OscillatoricB is particularly 

 interesting, from the fact that we may not unreasonably expect 

 to find in it a key to the singular motion from which they 

 have received their generic name, and which now, for more 

 than a century,* has formed an object of curiosity and interest 

 to the microscopist without having received as yet a satis- 

 factory explanation. In one species at least, I think, I have 

 been able to make out the leading features of its structure 

 and the mechanism of its locomotion. The description of 

 this, to me, new species I wish to preface by a few observa- 

 tions, containing some new facts regarding the structure of 

 Oscillatoria in general, which may, perhaps, interest some of 

 your readers ; in doing so, it will, however, not be necessary 

 to refer to the general character of these interesting organisms, 

 as they must be familiarly known to every one who is in the 

 habit of using the microscope, and therefore I plunge at once 

 in medias res. 



The following different tissues are observable in the true 

 OscillatoricB : — 



1. An outer enclosing sheath ; 



2. A special cell-membrane, with its contents ; and 



3. The axis, or pith, of the filament; 



which we shall consider in the order here stated. 



The filaments of certain species are enclosed in sheaths 

 (vaginae) or continuous tubes, never showing any cross- 

 markings corresponding to the striae of the filament ; they are 

 composed of a kind of cellulose, since, though they remain 

 unaffected by iodine, I have never been able to produce, on 

 subjecting them to the usual tests for cellulose, that peculiar 

 and striking blue colour characteristic of this substance. In 

 other species, these tubes are wanting, or Lave not yet been 

 observed. They are easily recognized ; when present, they 

 will be found projecting on one or both sides of the filament, 

 being considerably longer than the latter. Filaments enclosed 

 in their sheaths never, or but slightly, exhibit their peculiar 

 motions, though they may be seen sliding in them, back 



* Their movements were first observed by Adauson in 1753. 

 VOL. IV. S 



