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, Well-developed bud 

 is shown on the right; B, base; o, ovary; T, testis. (From Korschelt and Heider, 

 after Aders.) 



the wall of the column. This is caused by 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. 



