INFUSORIA. 



41 



on animalcules, wbich it takes by means of its trunk, transferring them to its mouth, 

 after the elephant's manner of feeding. It has a number of contractile vacuoles, from 

 ten to fifty, arranged in two longitudinal rows, as mentioned on a previous page. * It 

 is one of the largest knoT\ni Infusoria. 



The next family (TEicnoiJ^rjiriiiD^) is characterized by the ])ossession of a mcm- 

 braniform expansion as well as cilia. The type may be illustrated by the interesting 

 Trychonympha agilis (Figs. 40 and 41), described by Leidy as parasitic in the digest- 

 ive canal of the white ant, Termes jlampes. He observed that the canal was dis- 

 tended by brown matter, which on examination proved to consist largely of infusorial 



Figs. 40 and 41. — Trichonymxilia agilis, enlarged 450 times, n. Nucleus, i. Ingested food particles. 



parasites and particles of wood. Three species, belonging to as many genera, were dis- 

 covered. Fig. 40 represents T. agilis in its extended position. As it progresses in its 

 medium it takes on many protean forms. The cilia are arranged apparently in series, 

 some longer than others. The oral aperture is terminal. Until its life-history shall 

 h.ave been made out, its place in the system and its relation to its companions are 

 uncertain. 



The mouthless Holotricha (Opalixid^) are all parasitic, degraded fonns. They 

 have been taken for the larvae of Distonue. These now unquestioned Infusoria should 

 1)0 looked for in the intestines of frogs, mollusks, and worms. Opalina and Anoplo- 

 phrya are examples. 



Sub-Oeder II. — Hetekotricha. 



As was mentioned on preceding j'^ge, the Heterotricha are characterized by tlic 

 jiossession of cilia on the whole surface, those surrounding the mouth being longer 

 than those on other portions of the body. In all except JBursaria and its allies the 

 above definition holds good ; there the oral cilia do not encircle the mouth. With 

 the mention of these exceptions, we may now pass to a consideration of a few of 

 the typical forms. 



In Spirostomicm are met Infusoria which at once arrest the attention, both by their 

 elongate, snake-like form and their remarkable anatomy. Sp>irostomum umbirpoaii 

 (Fig. 22) may serve to illustrate their striking features. The figure represents the 



