OF ANIMALCULES. 147 



imperfect observation, with shallow magnifiers, gives the 

 cilia, in certain positions, the appearance of horns. 



The most usual form in which these creatures are ob- 

 served, is shewn at figure 209 ; the lower end of which 

 represents a portion of a leaf of duck- weed, to which the 

 animalcule is attached : around the upper part are ar- 

 ranged a series of cilia, which, when put in motion, pro- 

 duce a rapid current in the water towards the mouth of 

 the Vorticella. In this drawing, w^hich I made from 

 actual observation, the animalcule was slightly con- 

 tracted, and very transparent towards the upper part : 

 the cilia were very distinct, and the whole measured 

 the 1-lOOth of an inch in length. 



These creatures often detach themselves, and swim 

 about freely in the water; they are then generally observed 

 in the form shewn at figure 224, and are called trumpet 

 Animalcules, or funnel-shaped Polype. The body is some- 

 times quite straight, and not curved as in the drawing; 

 in the former position, they glide along in the water, 

 occasionally revolving about a line parallel to one of their 

 sides, which gives them an oscillating appearance : from 

 this peculiarity, which has not hitherto been noticed, I 

 presume the mouth aperture is not in the centre of the 

 circle of cilia, but near the margin, as in the Vorticella 

 convallaria: while swimming, the cilia are generally in- 

 visible, and the animalcule is often contracted and altered 

 in form ; it likewise swims occasionally with the tail 

 foremost, the axis of rotation being then the axis of the 

 animal. 



