Prof. Ehrenberg's Researches on tlie Infusoria. 221 



before they were distinctly seen to excite currents, and swallow 

 the coloured particles. In the genus Vorticella there seems to 

 be a combination of the oviparous and gemmiparous generations. 

 The single species Convaliaria, has, from their entire ignorance 

 of its mode of development, been subdivided into no less than 

 six distinct genera, by different observers, according to the Va-" 

 riety in its form at different stages of its existence. It first 

 appears in the form of minute points, not more than j 5^5 5th of 

 a line in diameter, scattered upon the peduncles of a group of 

 adult Vorticellae. After a time these minute points enlarge in 

 si2e, and send out delicate peduncular prolongations to the larger 

 adult roots, in which state Schrank styled them Vorticella mo- 

 nedica. When still more advanced, these peduncles become 

 coiled up in a spiral form. And when they may be considered 

 as having reached their complete organic development, though 

 still much inferior in size to what they afterwards attain, the 

 usual currents may be observed in the coloured solutions in 

 which they are immersed. The same species propagates itself 

 by gems, on the separation of a part of its body from the parent 

 trunk. This is performed in three different ways, each of which 

 has been dignified with the title of a distinct form. 



The first is the longitudinal division in which the animal di- 

 vides itself into two nearly equal halves. A fissure first appears 

 traversing the whole length of the body ; this becomes deeper 

 anteriorly, where two horns are now visible, each provided with 

 a distinct set of ciliae, and a mouth, recognisable by the two 

 currents of colouring particles directed to the apices of the two 

 horns. The fissure becomes deeper and deeper, till they form 

 two distinct, perfectly formed animals, attached to the apex of 

 a single peduncle ; one of these is soon detached from the lat- 

 ter, when it agrees in form exactly with Lamarck''s genus Urceo- 

 laria. AVhen the same animal moves with the hinder part for. 

 ward, it forms Schrank's genus Ecclissa ; when the conical basis 

 by which it was attached to the peduncle, has not quite disap- 

 peared, it forms Bory de St Vincent's genus Rinella ; and when a 

 little broader and more bell-shaped, with apparently only two 

 ciliae, it is the genus Kerobalanus of the same author ; when 

 fully provided with ciliae, without any remaining vestige of the 

 conical appendage, it is the genus Craterina. This Vortictlla 



