SEARS CROWELL 



303 



intermittent, not continuous. Figure 6 summarizes the experimental 

 results. The groups are arranged in the order of decreasing food 

 supply, and in each group the oldest upright is No. 1 at the left. In 

 the well fed groups, glut and 4 2, old and young uprights had grown 

 at the same rate. In all the others the younger grew faster (4). 

 The effect of age of stem in slowing or limiting terminal growth 

 was studied further (8). In one test the more basal levels of an up- 

 right were removed every few days so that it consisted of only the 

 4 to 8 youngest hydranths. The terminal growth, in these cases, 

 did not stop; the total length of stem produced was more than three 



12 3 4 S 6 7 8 9 10 



u uuuuuuuuu 



I 13 4 5 6 7 B 9 10 II 



uuuuuuuuuuu 



GLUT 



2- 



— 



<- I. 



dD 



nn 



nD 



r~ini~ir~ir-ir-ir-n— inrnf— 1 



JD. 



oD 



2 5/ 



JIL 



jnEL 



^n 



lO 



dddD 



r-ii-ir-n-ir-ir-n-ii-ir-n-n-i 



34 56 78 9 10 II 



Fig. 6. Terminal growth related to nutritive level and to age (height) of 

 upright. The subfigures are arranged in decreasing order of nutritive 

 level; within each the oldest upright is at the left. (With permission; Fig. 3 

 of ref. 4). 



