284 



HARRY DEAL TORREV. 



The second series of experiments involved 14 heteromorphic 

 pieces whose proportions and stage of development are represented 

 in the accompanying diagrams (Fig. 8). These pieces were cut 

 as indicated in the diagrams. Four days later, both parts of a, c, 



FIG. 3. 



FIG. 4. 



d, e,f, h, i, I, were attached and possessed frustules; the polarity 

 of one of the pieces in each of these cases, accordingly, was com- 

 pletely reversed. At the same time, both portions of b were 



FIG. 5, 



regenerating as single polyps, one being attached and furnished 

 with frustules, the other being unattached and lacking frustules. 

 Under g, four heteromorphic pieces were grouped. Four days 



