30 



INTRODUCTION TO PROTOZOA 



Ciliata and Sporozoa has been based. The simplest type of 

 movement is by means of simple outflowings of the body proto- 

 plasm known as pseudopodia (Fig. 2A). This is the common 

 type of movement in one of the four great classes of Protozoa, 

 the Sarcodina. In the FlageUata the organelles for locomotion 

 are long lashlike outgrowths known as flagella (Fig. 2C), from 

 one to eight or more in nmnber. These originate from a parti- 

 cle of deep-staining material which is called the blepharoplast or 

 " centrosome." In many parasitic flagellates there is another 

 deep-staining body, of very variable size and form, known as the 



parabasal body (also 

 called by some au- 

 thors the kineto-nu- 

 cleus or blepharo- 

 plast). Various types 

 of parabasal bodies 

 are shown in Fig. 3. 

 This body usually 

 arises from the basal 

 granule and often 

 remains connected 

 with it, apparently 

 being associated with 

 the function of loco- 

 motion. From the 

 fact that it seldom 

 occurs except in 

 parasitic forms it is possibly a special adaptation to the peculiar 

 environment encountered by such animals. By some protozo- 

 ologists the parabasal body has been looked upon as a second 

 nucleus with the special function of control over the locomotor 

 activities of the animal, and it has been thought to originate by 

 direct division from the main nucleus, but there is no conclusive 

 evidence for this view. As a result of the idea that the parabasal 

 body is of nuclear nature some workers have separated those 

 protozoans which possess a distinct " kineto-nucleus " from those 

 which lack it, creating the order " Binucleata " for them. 



In the Ciliata the organs of locomotion are in the form of cilia 

 (Fig. 2F), hairlike outgrowths which are shorter and more 

 numerous than flagella and different from them in motion. 



Fig. 3. Types of parabasal bodies (p). A, Leish- 

 mania; B, Herpetomonas; C, Trypanosoma; D, Prowa- 

 zekia cruzi; E, Prowazekia lacertas. 

 Trichomonas augusta. 



F, Polymas; G, 



