48 



LIFE, IN ITS LOWER FORMS. 



delicate, could hardly be removed by other creatures. 

 Instead, therefore, of being helpless at their birth, the 

 young Sponges can, by means of their cilia, row them- 

 selves about at pleasure, and enjoy for a period powers of 

 locomotion denied to their adult state."'" 



* Outline of Anini. Kingd. 17. 



