PARASITES OF PROTOZOA 1029 



around the axostyle of Devescov'ma glabra a short distance posterior 

 to the parabasal body. It is conspicuous in the species in several hosts, 

 in some of which it has been found in all specimens from several 

 colonies. Usually the limits of the group are well defined, and it has the 

 form of a thick ring around the trunk of the axostyle. The bodies are 

 generally short rods or granules; in some specimens from one host 

 the group consisted of long rods. Their properties of fixation and 

 staining exclude the possibility that they are mitochondria. In division 

 stages the bacteria are dispersed. Most species of Devescovina have no 

 such bacterial aggregate. 



Pierantoni found no "chromidial zone" in Mesojoen/a decip'iens, but 

 a similar area was occupied by filamentous bacteria. Kirby (1932a) 

 described as a "proximo-nuclear parasite" a group of bacteria, usually 

 rod-formed or filamentous and often bent or curved (Fig. 219A) , located 

 in a mass surrounding, or in proximity to the nucleus of all specimens 

 of Trichonjmpha campanula and T. collavis. The suggestion was made 

 that the organism may depend for its nutrition upon immediate proximity 

 to the source of the nuclear influences upon metabolism. 



The peripheral granules located in the outer zone of the ectoplasm 

 of the flagella-bearing region of T, collarh and T. turkestanica (Kirby, 

 1932a), which stain with the Feulgen reaction and show stages of appar- 

 ent division, are probably localized bacterial symbionts. They have not 

 been found in other species of Trichonympha. Ectoplasmic granules, 

 considered by the authors to be bacteria and constant in occurrence and 

 distribution, were described by Kirby (1938a) as immediately under 

 the surface layer of Pseudodevescovina ramosa, and by Grasse (1938) 

 as in a similar position in P. punctata. Similar peripheral bacteria occur 

 in Bullanympha silvestrii (Kirby, 1938b). Grasse found minute bac- 

 teria more deeply situated under the surface of P. brevkostris. Kirby 

 (1932a) discussed the similarity between the peripheral granules of 

 Trichonympha and those described in certain c'iliates. 



A still more remarkable localization is that of certain bacteria which 

 occur on the capitulum of the axostyle. Not all granules that occur in 

 that location are held to be bacteria, but some seem definitely to be. 

 Rods on the capitulum of Pseudodevescovina unijiagellata were 

 described by Kirby (1936) as probably bacteria. These were present 

 in a large percentage of specimens, but not in all; and in only a very 



