PARASITES OF PROTOZOA 1037 



ments; but it seems possible that the differences in refr activity noted 

 by Hafkine may have indicated the same structure upon which Pet- 

 schenko based his interpretation of nuclear organization. The latter author 

 found micronuclei to be absent in ciliates with Drepanospira; so that, 

 allowing for differences in detail of observation and interpretation, 

 it seems not impossible that H. undidata and D. mulleri are actually the 

 same. 



Hafkine spread the infection by introducing infected paramecia into 

 cultures. In early infection he noted no anomalies in the ciliates, but 

 development of the parasites proceeds rapidly and by the next day all the 

 contents of the infected nucleus are used up. When the parasite fills 

 up a large part of the ciliate, development of the latter is arrested, and 

 the same phenomena appear as in insufficient nutrition. Bozler (1924) 

 and Fiveiskaja (1929) noted the vacuolization of animals in which the 

 macronucleus was parasitized, the accumulation of fat drops and excre- 

 tion granules, and the reduction and disarrangement of the trichocysts. 

 Food-taking, digestion, and defecation continue for a long time, accord- 

 ing to Fiveiskaja, but the number of food vacuoles formed becomes pro- 

 gressively fewer. In late stages food currents are absent, there are no food 

 vacuoles, and the mouth, gullet, and cytopyge may disappear. There is 

 partial atrophy of the ciliary coat. At first there is no change in the 

 activity of the pulsating vacuole; later the shape of the canals changes 

 and the pulsations become slower. Eventually, with large masses of 

 parasites, the pulsations stop and the ciliate dies. 



Petschenko found that the cytoplasmic (or micronuclear) parasite 

 Drepanospira mulleri causes the cytoplasm to take on an alveolar char- 

 acter, and that the macronucleus undergoes degenerative changes and 

 may fragment and dissolve. He noted that a chemical action on the cell 

 is indicated, waste products and secretions of the parasite entering the 

 cytoplasm of the cell. There is intoxication of the cell, acting directly 

 on the cytoplasm, indirectly on the nucleus. Bozler stated that the possi- 

 bility that degenerative changes are to be traced back to the influence 

 of a bacterial toxin is not excluded; and Fiveiskaja thought that the 

 changes external to the nucleus were influenced by a substance excreted 

 from the macronuclear parasites, probably a toxin. Destruction of chro- 

 matin, with consequent disturbance of the normal macronuclear control 

 of metabolism, together with the mechanical influence of large masses 



