THE INFUSORIA 



407 



nricronuclei. 



Some species 

 $ 



coloured 



m 



blue with Stentorin, others red, 

 brown, green, or colourless. 

 They swim rapidly with a 

 rotatory movement, or attach 

 themselves by their narrow pos- 

 terior ends to a foreign object. 

 Sometimes, in the sedentary 

 condition, they form gelatinous 

 tubes. 1 mm. or more in length 



FIG. 59. 



Bursaria truncatella, O.F.M. The peristome is, 

 in this form, a deep excavation, the margins of 

 which embrace a considerable part of the anterior 

 and ventral surfaces (p). It can be closed by a 

 sphincter myophan band (s). A thin vertical fold 

 projects into this cavity on the right side (left in 

 the figure), and a thicker striated fold projects 

 into it on the left side. On the dorsal side there 

 is a gutter (m) leading down to the mouth, and 

 this is continued into a narrow oesophagus (o). 

 (After Schuberg.) x ca. 50. 



Fio. 60. 



Bursaria truncatella, O.F.M. Diagram 

 of a preserved specimen to show the long 

 strap-shaped meganucleus (M), and 16 

 micronuclei (m, m). (Constructed from 

 the researches of Prowazek.) 



FIG. 61. 



Stentor polymorphiis, 

 Miiller. A group of indi- 

 viduals attached to a water 

 weed, x 50. 



FIG. 62. 



An empty Spirorbis shell 

 bearing a large number of the 

 tests of Folliculina ampulla. 

 (After Stein.) x ca. 5 diam. 



Fio. 62A. 



A specimen of Folliculina as 

 it is seen when retracted into 

 its test (<). (After Stein.) 



when fully extended. Freshwater. (Fig. 61.) Folliculina, Lamark. The 

 peristome extended into a pair of large, lateral, wing-like processes. It 



