THE OPALINID CILIATE INFUSOFJAKS. 



mit<^, B. mawitanicus, liana esculenta and Triturus vuhjaris [" Tri" 



ton taeniatus "] . Its general appearance is shown in figure 3. It is 



a species of rather large size, being 



generally from 0.18 mm. to 0.36 



mm. in .length during the major 



part of the year, while living in the 



rectum of its adult host. The 



broadly rounded anterior end is 



usually turned to one side. The 



posterior end of the body tapers to 



a rounded point. 



The whole surface of the body 

 bears cilia which are arranged 

 in longitudinal, somewhat spiral 

 rows. In this species, as in most 

 others, the main rows of cilia run 

 the whole length of the bod}', 

 but, anteriorl}', accessory rows are 

 interpolated between the main 

 rows (see fig. 163, e, p. 194), caus- 

 ing the cilia to be more numerous 

 to the unit of width upon and near 

 the front end of the body. In 

 Protoopalina intestinalis the rows 

 of cilia over the anterior quarter 

 of the body are about twice as close 

 together as they are over the pos- 

 terior three-quarters. In some 

 other species the accessory rows 

 of cilia, interpolated anteriorly, 

 arp still more numerous, the cilia 

 rows in front being three times as 

 close together as they are behind, 

 or in a few species four times. In 

 some species, on the other hand, 

 the cilia rows are almost as closely 

 placed behind as in front. 



All the cilia in Protoopalina in- 

 testinalis are alike in form and 

 size. In none of the Opalinidae 

 known are the cilia upon the body 

 of different kinds, except that in 

 several species the cilia grow grad- 

 ually shorter toward the posterior end of the body, and in a few 

 species the posterior end of the body is naked. The axial fiber of 



Fig. 3. — Protoopalina intestinalis : 

 semi-schematicj longitudinal, opti- 

 cal section, x about 460 diameters. 



