POLYGASTRICA. 81 



motion, and by which they move in various ways, 

 some gliding slowly, others rapidly, some again 

 darting from place to place, and many having 

 a rolling motion : indeed, their modes of progres- 

 sion are almost as various as their forms. The 

 methods of reproduction are principally three : 

 by eggs, which is the most common ; by self- 

 division of the body ; and by the growth of buds, 

 or gemmules, upon the parent. They increase at 

 a most rapid rate, by each of these methods. I 

 have watched the self-division frequently, and 

 more particularly in the Vorticella convattaria, as 

 that interesting animalcule is attached to weeds, 

 so that its movements can be noted with great 

 certainty. I shall describe the process when I 

 more particularly mention that species. There 



