THE MANIFESTATIONS OF LIFE 79 



removing minute inhaled particles from the deeper 

 portions of the respiratory tract. 



The Fallopian tubes are also lined with cilia whose 

 lashings directed toward the uterus facilitate the passage 

 of the mature ovum from the ovary to that viscus. 



Flagella are longer coarser processes not clearly differ- 

 entiable from cilia, but usually occurring in smaller 

 numbers. As has been said, custom sanctions the use of 

 the word flagella in regard to the cilia of bacteria. In 



FIG. 26. Trypanosoma lewisi. A flagellate parasite of the blood of the rat. 

 X 1000. 



these lowly vegetable organisms they may appear like 

 cilia in that they sometimes arise from all parts of the 

 surface of the organism or like the flagella of the protozoa 

 in that they arise from one or both ends of the cell. 



In the flagellata they may also arise from one or both 

 ends, and may be single or multiple. In the highly 

 motile forms of flagellate protozoa, such as the trypano- 

 somes, they usually project anteriorly and possess a 

 spiral movement by which the animal is drawn through 

 the fluid medium in which it lives. 



