212 GEO. W. TANNREUTHER. 



tinct regions. The cells more centrally placed (Fig. 3, a), which 

 correspond to the distal end of bud, become inactive, while those 

 on either side of the central -region continue active, divide rapidly 

 and contribute almost entirely to the rapid growth of the bud. 

 There is a slight curvature in the mesoglea (Fig. 3, m), and the 

 enteron of the new individual becomes apparent. In a stage little 

 later than the preceding (Fig. 4), the relation of bud to parent 

 and the condition of cells is more plainly represented. Fig. 5, 

 a portion of Fig. 4 at a, represents the entire area that contributes 

 directly to the growth of the bud. The cells at the apex of the 

 forming bud are small. Those on either side are larger and more 

 active in the process of division and growth. Their contents is 

 very similar, showing an abundance of food material and cyto- 

 plasmic granules. 



The ectoderm and endoderm at the junction of the parent and 

 bud (Fig. 7) divide very rapidly and become the most active 

 growing region in the production of the new individual. The 

 remaining cells of the bud seldom divide. The formation of the 

 tentacles is similar to that of the buds. The cells corresponding 

 to their basal ends take the most active part in their growth. The 

 mouth is formed at the distal end of the bud by a breaking 

 through of the ectoderm. 



The rate of growth of the bud is determined by the amount of 

 food present. In an active feeding hydra, the buds are often 

 completely formed in thirty to forty hours. While in those 

 hydras with a moderate supply of food the buds grow very slowly 

 and may require four or five weeks or even more time for their 

 complete development. In the latter instance after the buds are 

 nearly formed, they will be absorbed in the absence of food. In 

 the process of absorption the cell walls of the bud become imper- 

 ceptible and the cell contents presents the appearance of a com- 

 plete syncytium. When the buds are nearly absorbed, if the 

 hydra is again supplied with food, the buds very seldom reform. 

 In a few instances the buds were neither absorbed nor reformed, 

 but remained attached to the parent as permanent individuals. 

 Tentacles were formed later. 



When the buds have reached their complete development the 

 ectodermal cells at the proximal end undergo a rapid change 



