930 



PROTOZOA AND OTHER ANIMALS 



may appear for nutrition. Probably also in that category is the increase 

 of the number of flagella and the development of undulating membranes 

 and axostyles in certain groups of flagellates. In the latter category are 

 the reduction or loss of cilia, the reduction or loss of mouth structure, 

 the elaborate development of the parabasal apparatus and other or- 

 ganelles in certain polymastigote flagellates, the complex characteristics 



Figure 196. Streblomastix strix attached to the lining of the hind-gut of Zootermopsis 

 angusticollis. (After Kofoid and Swezy, 1919.) 



of many hypermastigotes, the elaborate morphological specialization of 

 Ophryoscolecidae. 



Organelles of fixation appear among flagellates in epibiotic dinoflagel- 

 lates (Chatton, 1920; Steuer, 1928); in Streblomastix strix, which often 

 is attached (Fig. 196) to the wall of the hind-gut of its termite host, by 

 a holdfast (Kofoid and Swezy, 1919; Kidder, 1929); in Pyrsonympha 

 and Dinenympha, which occur free in the gut lumen of Reticulitermes or 

 attached by a small, simple, anterior knob (Koidzumi, 1921); and in 

 Oxymonadinae. In the last group the holdfast, which is applied to the 

 intima of the termite gut, is at the end of a rostellum, which may reach 

 a relatively great length and often contains many fibrils (Kirby, 1928; 



