OTHER PROTOZOA 



Chlamydomonas (Fig. 43) is found in ponds, ditches, and rain 

 pools. It is oval in shape, green in color, and swims about by 

 means of two flagella (g) which project from one end (Fig. 43 A). 

 The central mass of protoplasm is covered by a definite wall of 

 cellulose. Within the cells are a nucleus (k), two small contractile 

 vacuoles (v), a large pyrenoid (py), a red pigment spot (a), the 

 stigma, and chromatophors (chr). 



Reproduction takes place in two ways. First, a cell comes to 

 rest and its contents divide into two, four or eight daughter cells 

 which assume the characteristics of 

 the parent organism and lead a 

 separate existence (Fig. 43 B). Sec- 

 ond, a cell may divide into from six- 

 teen to sixty-four cells without walls; 

 these are smaller than the vegetative 

 cells, but resemble one another. 

 They are known as gametes. The 

 gametes fuse in pairs (Fig. 43 C), 

 forming spherical bodies with heavy 

 walls called zygotes (D); after a 

 period of rest, the contents of the 

 zygotes divide into a number of 

 parts which escape from the walls 

 and grow into vegetative cells. 



Spondylomorum (Fig. 44) differs from Chlamydomonas in a 

 number of particulars, the most noticeable being its colonial 

 habit. Specimens may be found in situations similar to those 

 cited for Chlamydomonas. When brought into the laboratory 

 they collect at the side of the culture dish nearest the window, 

 reacting positively to light of moderate intensity. Sixteen cells 

 form a colony; they are arranged in four rows of four each, alter- 

 nating, as shown in Figure 44. Each cell appears to be exactly 

 like every other cell ; it possesses four flagella and has a chloro- 

 phyll body which enables it to manufacture its own food. All of 

 the somatic functions are carried on by each cell independently 



FIG. 44. Spondylomorum. 

 (From Oltmanns.) 



