64 THOUGHTS ON ANIMALCULES. 



The Stephanoceros appears under the microscope 

 like a cylindrical vase, as clear as crystal, surmounted 

 by a crown formed by the convergence of the points of 

 five long arms, or tentacula, each fringed with about fif- 

 teen row^s of delicate, short, verticillate cilia, which are 

 in constant oscillation, (see pi. ix). The vase contains 

 several bodies of different colours: these are the internal 

 organs, and the Monads and other polygastrians that 

 have been swallowed. The rotatory organ in this ani- 

 malcule is wholly unlike that of any other of the class. 

 It is deeply divided down to its base into five long pro- 

 cesses, which may be regarded as ciliated tentacula, for 

 they are flexible and prehensile, and employed by the 

 animal to retain the prey brought within the vortex 

 produced by the vibrations of the cilia. The arms are, 

 however, limited in their action, and, so far as my ob- 

 servations extend, do not appear capable of being 

 lengthened and shortened, or of bending outwardly 

 and laterally, like the tentacula of the Hydra*. 



present residence the attempt to preserve these animalcules alive, even 

 for a few days, has been unsuccessful, and the eggs have in no instance 

 reached maturity. As the precaution was taken to supply them with 

 water from their native lakes, the mortality must be ascribed to some 

 local condition of the atmosphere. The descriptions in the text refer to 

 observations made in 1843 by me and my late assistant Mr. H. Lee, now 

 Conservator in the College of Surgeons of Edinburgh. 



* From these ciliated arms, which are arranged around the mouth as 



