INFUSORIA. 



41 



on animalcules, which 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 known Infusoria. 



The next family (Teichonymphid^) is characterized by the possession of a mem- 

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

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

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

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



riGS. 40 and 41. — Trichonymplui 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 

 have been made out, its place in the system and its relation to its companions are 

 uncertain. 



The mouthless Holotricha (Opalinid^) are all parasitic, degraded foiTUS. They 

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

 be looked for in the intestines of frogs, moUusks, and worms. Opalina and Anoplo- 

 phrya are examples. 



Sub-Oedee II. — Heteeotricha. 



As was mentioned on preceding page, the Heterotricha are characterized by the 

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

 than those on other portions of the body. In all except Bursaria 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 Spirostomum are met Infusoria which at once arrest the attention, both by their 

 elongate, snake-like form and their remarkable anatomy. Spirostomum amMguum, 

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



