PHYLUM PROTOZOA 



45 



tionable nature of the so-called flagella of certain parasites belonging 

 to the genus spirocheta, many of which are said to have flagella. 

 These so-called flagella are apparently variable structures, for in 



Fig. 16 



B 





Trypanosoma rai;r. (After Robertson.) Forms observed in tlie digestive tract of tlie leech 

 Pontobdella muricata. ,1, mature specimen from blood of skate; B to F, stages in tlie 

 development of the flagellum from the kinetonucleiis, and change in position of the latter in 

 relation to the nucleus. 



many ca.ses as "difFu.se flagella" they appear not only at the ends of the 

 cell, but at dittVrent points about the periphery, and there S(>ems to be 

 no uniformity about their distribution. This is said to l)e the case in 



