PROTOPHYTES. 8? 



5. The family Volvocinea has been long considered 

 of singular beauty and interest to the microscopist. 

 The Volvox globator (Fig. 26) was described by Leeu- 

 wenhoek about 

 one hundred and 

 fifty years ago, 

 and from its shape 

 and rolling mo- 

 tion was called the 

 globe animalcule, 

 but its vegetable 

 character is now 

 generally admit- 

 ted. It is about 



One thirtieth of FIG. 2 6.-Volvox globator. 



an inch in diameter, and appears to the unassisted eye 

 to be a little green speck moving slowly through the 

 water. On examining with the microscope the Volvox 

 is seen to be a pellucid sphere studded with minute 

 green spots, connected together by threads. From each 

 of these spots proceed two cilia, so that the entire sur- 

 face of the globe is beset with vibratile filaments, to whose 

 combined action its rolling motion is due. Within the 

 globe may be generally seen from six to twenty other 

 globes, of varying sizes, which are set free by the burst- 

 ing of the parent globe. Sometimes a third generation 

 may be seen within the secondary spheres. Careful ob- 

 servation of the development of the Volvox has shown 

 that the ciliated cells referred to above, analogous to the 

 zoospores of Protococcus, sometimes appear like moving 

 Amoebae. (Chap. II, Sec. 2.) This is not an uncommon 



