8 4 



C. M. CHILD. 



are very deeply colored, in fact large hydranths are often still 

 completely opaque. The gradients are similar in the campanu- 

 larian hydranth. 



The Gradient in Hydranth Buds. In Bougainvillea the buds 

 show very distinct apico-basal gradients in rate of reduction from 

 early stages on, and in material dehydrated and cleared after 



complete reduction the basipetal gradient appears in both ecto- 

 derm and entoderm. Figure 2 shows a somewhat advanced bud, 

 the left side in surface view indicating the gradient in rate 

 of reduction, the right side in optical section indicating the 

 gradient in amount of reduction in cleared material. 



In Obelia, Gonothyrcea and other campanularians the axis of 

 the colony is, as I have pointed out, sympodial and the bud 

 which originated as a lateral bud below the terminal hydranth 

 or the terminal bud undergoes considerable growth in length as a 

 continuation of the main axis of the colony and may even give rise 



