54 



ORGANISMS OF ONE CELL 



dragged along by the vigorous lashing of the water by these 

 flagella, and turning round and round on its long axis as it 

 moves forward. 



It is because of the flagella that Chilomonas is classified as 

 one of the Mastigophora or whip-bearing protozoa. 



The flagella are extremely delicate, and impossible to see when 

 the organism is moving, but when the cells are killed with iodine 

 they can be made out easily. They are of uniform diameter 



FIG. 21. Flagellated protozoa, Chilomonas, Peranema, and Euglena. A, 

 Chilomonas paramecium', B, Peranema trichophora at beginning of division, i, 

 Flagella; 2, basal bodies of flagella; 3, basal body with young flagellum growing 

 from it; 4, parabasal body; 5, nuclei. Drawings and photograph from prepara- 

 tions. 



throughout, entering the body at about the center of the 

 truncated plane and continuing into the protoplasm as far as 

 the nucleus. The latter has a different structure from the 

 nucleus of Amoeba proteus, and consists of a relatively large 

 granule (division center) surrounded by minute granules of 

 chromatin, and with a delicate nuclear membrane. Between 

 the nucleus and the truncated end of the cell is a somewhat 

 cone-shaped mass of denser protoplasm which is probably the 

 main seat of food assimilation. The remaining protoplasm has 

 a distinct alveolar structure, the alveoli about the periphery 



