248 



CASWELL GRAVE 



TABLE 1 



Showing the levels at which tadpoles became attached when subjected to various 

 light conditions in a 1000-cc. glass cylinder filled to the 40-cm. mark 

 with sea-water 



1 The number of tadpoles remaining at the top in experiments 3 and 4 seems 

 abnormally large. It is possible that some of the tadpoles were not in good 

 condition due to the fact that the parent zooids had been kept too long under 

 laboratory conditions. 



