FLAGELLATA 



123 



transition towards them; for the flagellate, nutritive cells of the 

 Sponges are provided with a collar, which exists in no other 

 group of Metazoa (see pp. 171, 181, and Fig. 70, p. 176). 

 The most recent monographer of the family is Eaoul Franc^, 

 but James-Clark and Saville Kent did the pioneering work. 



Of the life-history of the Trichonymphidae,^ all of which are 

 parasitic in the alimentary canal of Insects, especially Termites or 

 White Ants (Vol. V. p. 356), nothing is known. Some of them 

 have a complete investment of motile flagella, like enormously 



Fig. 41. — Opo.lina 

 ranarum. A, liv- 

 ing specimen ; B, 

 stained specimen 

 showing nuclei ; 

 C, stages in nnc- 

 lear division ; 



D - F, stages in 

 fission ; Gr, final 

 product of fission ; 

 H, encysted 

 form ; I, young 

 form liberated 

 from cyst ; K, the 

 same after multi- 

 plication of the 

 nucleus has begun. 

 M«, Nucleus. 

 (From Parker's 

 Biology, after 

 Saville Kent and 

 Zeller.) 



long cilia, which in Dineni/mpha appear to coalesce into four 

 longitudinal undulating membranes. Lophomonas inhabits the 

 gut of the Cockroach and Mole-cricket. The Opalinidae have 

 also a complete investment of cilia, which are short, and give the 

 aspect of a Cilia te to the animal, which is common in the 

 rectum of Amphibia, and dies when transferred to water. But 

 despite the outward resemblance, the nuclei, of which there may 

 be as many as 200, are all similar, and consequently this group 

 cannot be placed among the Infusoria at all. Opalina has no 

 mouth nor contractile vacuole. It multiplies by dividing 

 1 Discovered by Leidy. For the most recent description of this group see Grassi 

 and Sandias in Quart. Journ. Micr. Sci. xxxix. (figures) and xl. p. 1 (text), 1897. 



