AND ELUCIDATIONS. 



it is scarcely possible by any figure to express the genuine 

 habit of the animal, especially when arrived at its full 

 growth, when the branchings are extremely numerous. 

 It may be added that two or three distinct species of this 

 kind of compound Vorticellae exist, which are all evidently 

 confounded by Linnaeus and some others under the name 

 of Vorticdla anastatica. Their general mode of growth 

 or increase is as follows : viz. the first or parent animal 

 swims single, and is furnished with an extremely short 

 stem, hardly equalling the length of the body ; but 

 which, in a few hours, extends to a surprising degree, 

 and becomes the chief or general stem: after this the 

 body divides longitudinally, forming two distinct and 

 similar bodies, whose respective stems very soon begin to 

 lengthen, and, after some hours, each of these two bodies 

 again divides, forming double the former number. This 

 method of increase is continued till all the numerous 

 branches of the animal tree are formed ; and when it has 

 thus remained for the space of eight, ten, or even many 

 more days, the several animals separate, in succession, 

 from their respective branches or stems, and swim about in 

 order to form new colonies ; so that in the space of some 

 days the tree is left perfectly bare. To this, which is the 

 general mode of increase, the accurate Muller has added 

 a still more surprising one, viz. that the naked stems again 

 repullulate, producing new heads or bodies in place of 

 those which have departed. This latter mode of increase, 

 I must confess, has never yet fallen under my own ob- 



