200 



THE PROTOZOA 



inf usorian stem was derived from the flagellate at a very early period, 

 and that the side branch became progressively differentiated until the 

 well-marked characteristics of to-day distinguish the Infusoria as an 

 entirely independent group. The first forms to diverge from the 

 flagellate stem may have been like the type described by Cienkowsky, 

 under the generic name of Multicilia (Fig. 112, A), a form with a 

 number of long flagella. It is thought by Butschli that the Ciliata 

 might have been derived from such generalized forms by progressive 

 increase, with shortening of the motile elements, until cilia were the 



Fig. 112. A. Multicilia lacustris Lauterb. [LAUTERBORN.] 

 B. Pyrsonympha vertens Leidy. [PORTER.] x, the vibrating band in the inner plasm. 



outcome. There is no close connection, however, between cilia and 

 flagella, such as exists between the flagella and the pseudopodia. 

 Other forms, more or less similar to Multicilia, have been described 

 by various observers, so that the hypothesis of Butschli is not 

 without warrant. Among these forms are Grassia, TrichonympJia, 

 Leidyonella, Lophomonas, Pyrsonympha, etc., which are placed by 

 some among the Flagellidia (Delage), by others among the Ciliata 

 (Butschli). Another point of view has been based upon the relations 

 of the Ciliata to the Suctoria, and through them to the Sarcodina 



