36 



thinner at about its middle, and finally, just half an hour 

 after it first bf3gan to stretch out, it broke in two and 

 the bud fell away from the parent (Fig. 21). T}ie two ends 

 of the connectins-stalk shrank back into the tissue of the 

 bud and the X)arent, appearing for a time as drops or points 

 of protoplasm (Fig. 21). AJ'tor separation from the polyp, 

 this particular bud settled down at once upon the previous- 

 ly free or distal end, and began an independent existence 

 (Fig. 22). Otlier observations, however, indicate that the 

 usual course of development is slightly at variance with 

 this instance, and that it includes a period of from three 

 to four days, intervening between the detachment of the bud 

 and its settling down as a hydra, during which it has the 

 form of a free-swimming planula. A bud which v/as growing 

 upon the body-wall one day would be gone the next, and for 

 some time could not be found. Then suddenly it would ap- 

 pear in some previously vacant spot, at a distance from the 

 Ijolyp, perhaps in an entirely different watch-glass on the 

 bottom of the aquarium, with its tentacles just ber^inning 

 to appear. In one case the bud was drawn and measured , when 

 it seemed to have reached its full size and to be ready to 

 drop off; this was done one evening, and the next morning 



