1022 PARASITES OF PROTOZOA 



undulatory movement unlike that of cilia, have an uneven distribution, 

 and may quit the host entirely. They differ in staining from true cilia, 

 and their movement remains unmodified, even though the ciliate be 

 crushed. Faure-Fremiet considered them to be spirilla, but later ob- 

 servers (Cepede and Willem, 1912; Bach and Quast, 1923; Pellissier, 

 1936) recognized them as spirochetes. Bach and Quast reported spiro- 

 chetes also in the gut lumen, but found them present only when Tricho- 

 dinopsis was also present. 



Collin (1912) recorded a number of instances of the presence of 

 adherent mirco5rganisms on Suctoria. Short, rod-shaped bacteria, many 

 of them in division, were shown adherent full length, in a close-set 

 investment, on Discophrya lynghyei (Collin, 1912, his Fig. 17). Schizo- 

 phytes adherent by one end, often obviously simple phoretic micro- 

 organisms with no closer relationships, were found on the lorica of 

 Acineta tuberosa and on the tentacles of Choanophrya infundibuUfera. 

 Bacteria were adherent in a gelatinous investment on the surface of 

 several species of Paracineta. 



More recently, especially through the work of Kahl (1928, 1932), 

 the presence of characteristic types of rod-shaped bacteria on the sur- 

 face of certain marine ciliates — chiefly sapropelic — has become known. 

 The rods adhere either by one end, as on Parable pharisma pellitum 

 (Fig. 213G), P. collar e (Fig. 213H), Met opus contort us var. pellitus 

 (Fig. 213F), and the stalk of Epistylis barbata (Fig. 213E); or flat, as 

 on Cristigera vestita (Fig. 213C, D), C. cirri f era (Fig. 213B), Ble pha- 

 risma pestitum, Parable pharisma chlamydophorum (Fig. 2131), and 

 species of Sonderia. The presence of adherent bacteria is characteristic 

 of all members of the genus Sonderia. Many of these ciliates are covered 

 by a gelatinous layer, and it is to this that the bacteria adhere (Fig. 

 21 3A). Yagiu (1933) and Powers (1933, 1935) found bacilH con- 

 stantly adherent longitudinally to the surface of three species of Cycli- 

 dium from sea urchins, a different type on each species (Fig. 214) . Kirby 

 (1934) believed the protuberances of Metopus verrucosus (Fig. 213J), 

 which are irregular in distribution, to consist of groups of vertically ad- 

 herent bacteria. Kahl questioned this statement, but in view of what 

 we now know of bacteria on flagellates and ciliates it is not improbable. 

 Kahl (1933) maintained that the adherent bacteria are advantageous 

 symbionts, contributing somehow to the nutrition of their hosts; but that 



