CELLULAR STRUCTURE OF ORGANISMS 



91 



on the other hand the cells are all alike, are all capable of 

 carrying on the various functions of life, and may be more 

 or less independent of each other. 



Vorticella and Carchesium. Other examples of types inter- 

 mediate between unicellular and multicellular forms are shown 

 in Figures 39 and '40. The Vorticella, shown at Figure 39 A, 



FIG. 39. Two SPECIES OF UNICELLULAR ORGANISMS 



> Showing the formation of colonies. A, a single-celled Vorticella; B, the process of divi- 

 sion; C, a single cell of Carchesium; D, a colony of Carchesium, produced by the incom- 

 plete division. Vorticella always separates after division, but Carchesium remains attached 

 as shown at D. 



en, contractile vacuole; 

 oe, oesophagus; 

 m, mouth; 



mac, macronucleus; 

 mic, micronucleus. 



is unquestionably a single-celled animal, bell-shaped and pos- 

 sessing cilia, a mouth, oesophagus, vacuole, and a macro- 

 and micronucleus; the whole is attached to a stalk containing 

 a muscle which enables it to contract. This single cell divides 

 in a normal manner (B) and after division the parts separate 



