552 DESCRIPTION OF {PolygastricU, 



selves, which they devour entire ; this will account for the variety of 

 forms which they assume, and require an observer to be very watchful 

 and cautious before he can pronounce on the identity of a species. 

 Dr. Ehrenberg, by patient observation, saw one individual undergo a 

 great variety of forms when it had swallowed a young Kolpoda 

 cucullxis. To illustrate this, fig. 260 shews a young specimen with 

 open mouth, about to devour an animalcule ; this it accomplishes by 

 the motion of the fringe of cilia producing a current in the water ; 

 the prey by this means is brought into contact with the mouth, 

 which gradually dUates till the animalcule is entirely inclosed. 

 During tliis operation it swims about, and a casual observer would 

 imagine the form shewn at fig. 261 as the normal shape of another 

 animalcule, while, in fact, it is occasioned by its food ; as the di- 

 gestion proceeds the lower part dilates, and the anterior contracts into 

 its former shape ; the animalcule then assumes an egg shape (fig. 262 

 to 265); and finally returns to its true form. Found in stagnant 

 water. Length l-430th. 



Encilelys infiiscata. — Body oval or spherical, and whitish ; 

 mouth encircled by a brownish ring, and not prominent. When fed 

 with indigo numerous digestive cells become filled. Found in bog 

 water. Size l-280th. to l-240th. 



E nebulosa (M.) — Body ovate, hyaline, with a projecting mouth. 

 This species receives carmine and indigo very readily. Ehrenberg 

 has counted as many as nineteen digestive cells. Filled with the 

 coloured food. Size l-230th. to l-570th. 



Genus Disoma (?) Tlie douUe-hodied Animalcules. — This curious 

 genus is characterized by a double body, destitute of cilia; that part 

 at which the mouth is situated is truncated (direct.) The mouth is 

 ciliated, but devoid of teeth. Within the bodies numerous little 

 vesicular cells (stomachs) are observed, and the discharge of ex- 

 crement may be seen to take place at the posterior extremity of 

 each body. 



D. vacillans. — Consists of two corpuscles, filiform, and slenderly 

 club-shaped; hyaline and attenuated at the anterior extremity. 

 Ehrenberg remarks, " Both bodies frequently swam parallel beside 

 each other, so that they tui'ned on their long axis and moved onwards 

 quickly, though vacillating; sometimes both bodies gaped widely 



