PARASITES OF PROTOZOA 1027 



individuals of Pelomyxa vivipara, all the nuclei are enveloped by close- 

 set bacteria applied to the surface. Leiner stated that in P. palustrh bac- 

 teria may thickly invest the nuclei, especially in animals in which the 

 refractile bodies are small. Veley observed jointed rods attached to the 

 refractile bodies, and believed that these afford them a point of attach- 

 ment without which the cycle would not be completed. She thought it 

 probable that the refractile bodies, which she considered to be protein 

 in nature, serve the bacteria as a food supply. Leiner found evidence 

 that the long rods extract glycogen from the refractile bodies. 



Fortner ( 1934) studied the occurrence of bacteria in different forms of 

 P. pdustris. The large, club-shaped, gray-greenish forms were free of, or 

 poor in bacteria. The yellow ones contained very numerous small refractile 

 bodies, with large numbers of bacteria in proximity to these. The small, 

 spherical or pyriform, milky-white type contained no refractile bodies, 

 in place of which were the characteristic bacteria in vacuoles. The white 

 forms he believed to be degenerate, and thought it conceivable that the 

 whole metamorphosis of Pelomyxa might be conditioned by the bacterial 

 infection. Leiner (1924) also noted the variability in the number of the 

 rods and their abundance in yellow animals. He distinguished a second 

 species of parasite, smaller and less numerous than the other, distributed 

 in the cytoplasm (Fig. 215B). 



Leiner found reason to believe that when the bacteria are excessively 

 abundant, they become definitely injurious to the host. They may cause 

 hypertrophy, structural alteration, and eventual dissolution of the nuclei; 

 and the trophic functions of the cell appear to be disturbed. There is 

 decreased storage of glycogen. When Pelomyxa dies, the bacteria multi- 

 ply extraordinarily. 



Schizomycetes in Flagellates of Termites. — There are numerous in- 

 stances of a constant association with intracytoplasmic bacteria among 

 flagellates of termites, and often the microorganisms are restricted to 

 specific areas of the cell. There is not positive proof in all instances 

 discussed below that these are bacteria; but reaction to certain fixatives, 

 staining properties, comparison with known cytoplasmic inclusions, and, 

 frequently, observation of fission stages make it extremely probable. 



There is no evidence that the bacteria are harmful to the flagellates, 

 though it is possible that as regards certain ones some such evidence 

 may eventually be adduced. They may be referred to as intracellular 



