36 



BIOLOGY OF THE PROTOZOA 



polythalamous or many-chambered Foraminifera depending upon 

 the position assumed b}' the bud (Nodosarine, Frondicularian, 

 Rotah'ne t.^^pes, etc.). 



In colonial types the form of the aggregate is determined by the 

 manner in which the individuals are held together after division. 

 The different types are described as spheroid, catenoid, arboroid 

 and gregaloid colonies. In the majority of spheroid colonies, the 

 associated cells are held together b\' a gelatinous matrix secreted 



Fig. 14. — Tj^jes of spirally wound Protozoa. A, Streblomastix slrix. (After Kofoid 

 and Swezy.) B, Lacrymaria sp. (original) ; C, Heteronema sp. (Original.) 



by the individual cells. The typical form of such colonies is spher- 

 ical as in the various species of the genera Volwx, Vroglena (Fig. IS), 

 Pleodorina and Synvra among the flagellates, or Ophrydium versa- 

 tile among the ciliates. Such spheroidal colonies, however, are not 

 necessarily globular but may be flat plates of associated individuals 

 as in (jluvivm pectonde, or Platydorina caudafa (Fig. 3). In catenoid 

 colonies the individuals are attached end to end as in some species 

 of gregarines, or in the dinoflagellate Ceraiium, or side by side as 

 in the flagellates Chlorodesmiis and Chytridiasirum , or in the ciliates 



