36 



HANDBOOK OF IXVERTEBRATE ZOOLOGY. 



cavity of the bud long before this has a mouth of its 

 own. 



Fig. 16. 



Fig. 17. 



Fig. 18. 



Figs. 16, 17, and 18. — Three stages in the formation of a hydranth by 

 budding, magnified one hundred and fifty diameters. (Drawn from na- 

 ture by W. K. Brooks. ) 



a. Perisarc. b. Ectoderm, c. Endoderm. d. Body cavity. 



VI. Place a small healthy colony in a good supply of 

 fresh sea-water, and cutting some of the hydranths and 

 buds from the tips of the stems with a sharp pair of scis- 

 sors, trace their reproduction by a process which is very 

 similar to the normal method of buddino'. Durins; the 

 experiment, which occupies several days, the water should 

 be changed frequently, and it may require three or four 

 days for the colony to become sufficiently accustomed to 

 its confined life to commence the process. 



Confinement in too small a quantity of water often 

 causes certain abnormal changes which may be noticed. 



