CELLS, THE ESSENTIAL ORGANS OF LIFE. 27 



is formed ; (see pi. i, fig. 4). In a short time the young 

 separates from the parent, and assumes its individual 

 existence. Frequently several young ones, in various 

 stages of growth, appear on the same polype, and even 

 a third or fourth generation on the young themselves, 

 before their separation from the parent. Upon an 

 average, each individual sends out five or six young in 

 the course of a week ; the progeny of a single polype, 

 may, therefore, in a few months, amount to hundreds of 

 thousands. 



