346 



PATTERNS AND PROBLEMS OF DEVELOPMENT 



the same length may give rise to forms ranging from a complete individual 

 on a small scale (Fig. ii6, A) through unipolar and bipolar partial forms 

 (Fig. 1 1 6, B F) to unipolar or bipolar hypostomes (Fig. ii6, G, H).^^ 

 In short pieces bipolar frequency may be increased and scale of organiza- 



H 



Fig. ii6, A-H. — Corymorpha. Forms resulting from differences in scale of organization in 

 pieces of the same length. 



tion decreased by exposure to inhibiting agents for a short time after 

 section and unipolar frequency, and scale of organization may be increased 

 by differential conditioning to low concentrations of inhibiting agents or 

 by inhibiting development at one end of the piece. This is accomplished 

 in Tiihularia by closing the end with parafhn or sticking it in sand, and 



'•5 For earlier observations on unipolar and bipolar forms of Tubularia see authors cited in 

 footnote 6, p. 36. For partial forms of Corymorpha see Child, 19266, 1927a, b. 



