PROTOCOCCOIDE^:. 



49 



into 16 new ones (Fig. 45 B), each forming a new individual, 

 which soon grows to the size of the mother-individual. It was 

 in this Alga that the conjugation of self-motile gametes was 

 first discovered by Pringsheim, 1869. When conjugation is 

 about to take place, each cell divides into sixteen, as in vegeta- 

 tive reproduction, but the 16 x 16 cells all separate from one 

 another (Fig. 45 C, female gametes, and D, male gametes), and 



FIG. 45. Pandorina worum. 



swarm solitarily in the water. The male are, most frequently, 

 smaller than the female, but otherwise they are exactly alike ; 

 they are more or less pear-shaped, with a colourless anterior end, 

 2 cilia, a red " eye-spot," etc. After swarming for some time they 

 approach each other, two and two, generally a large and a smaller 

 one, and come into contact at their colourless end ; in a few 

 moments they coalesce and become one cell (Fig. 45 E, F), this 



W. B. E 



