REPRODUCTION 



219 



well as among the Coelenterata. The process is well exempli- 

 fied by hydra. The bud which is eventually to form a new 

 polyp is first seen as a slight protuberance of the lower part of 



Fig. 121. — Diagram of hydra in longitudinal section. A , Wcll-dt-vrlopctl bud 

 is shown on the right; B, base; 0, ovary; 2\ testis. (From Korschelt and Ileider, 

 after Aders.) 



the wall of the column. This is caused l)\- the more rapid 

 growth of the tissues in this region and involves both ectoderm 

 and entoderm. The bud grows larger, becomes cylindrical, 

 and finally a circle of tentacles forms around the distal end. 



