44 



PROTOZOOLOGY 



that it is difficult to recognize it in life under the microscope with 

 a moderate magnification. In a number of species, the flagellum, 

 however, can be seen in life as a long filament, as for example in 

 Peranema. As a rule, the number of flagella present in a single 

 individual is small, varying from one to eight, but in Hyper- 

 mastigina there are numerous flagella. A flagellum appears to be 

 composed of at least two parts (Fig. 8, a, h). An axial filament 

 which is elastic, takes its origin directly, or indirectly through 



d e f 



Fig. 7. Form-change in a limax-amoeba (Verworn). a, b, contracted 

 forms; c, individual showing typical form; d-f, radiosa-forms, after 

 addition of KOH solution to the water. 



basal granule, in the blepharoplast. Surrounding this filament 

 there is a sheath of contractile cytoplasm which varies in thick- 

 ness alternately on the opposite sides of the filament. The 

 flagellum ordinarily tapers toward its distal end where the axial 

 filament is said to be frequently exposed. 



Recently Vlk found, besides the kind above mentioned which 

 he called the whip-flagellum, another form named by him as the 

 ciliary flagellum. The latter is said to be uniformly thick, but 

 possesses dense ciliary projections which are arranged on a 

 flagellum in one or two spiral rows (Fig. 8, c, d). Vlk found the 

 whip-flagellum in Chlamydomonas, Polytoma uvella(e), Cercomonas 



