no 



C. M. CHILD 



cem the character of the head the results are given in table 1 

 in percentages. The different types of head distinguished in 

 the table are described fully in earlier papers (Child, '11 c, 

 '11 d). The normal head possesses equal, symmetrically placed 

 eyes and the cephalic lobes are lateral to the eyes. In the 

 teratophthahnic head the eyes are abnormal in position, number 

 or form, in the teratomorphic head the anterior region fails 

 more or less completely to develop and the cephalic lobes 

 appear on the truncated front end of the head or may be fused 

 together in the median line. The anophthalmic form shows a 

 distinct anterior outgrowth but no eyes and finally in the headless 

 form the anterior new tissue merely fills in the contracted cut 

 surface. 



These two sets of pieces a and h, which in water give results 

 practically identical except for the position of the pharynx, show 

 in alcohol a very great difference in regulatory capacity. The 

 a-pieces show a lower mortality and form heads more frequently 

 in alcohol than the 6-pieces. 



It is evident then that the regulatory processes in the two sets 

 of pieces which under the usual conditions lead to practically 

 identical results are not the same in their reaction to alcohol: 

 at the level of the old pharynx head-formation is much less fre- 

 quent than at a level near the old head. If we compare other 

 levels between these, as I have done in other series, we find that 

 under the same conditions their capacity for head formation lies 

 between these two extremes. 



These data demonstrate the existence of differences of some 

 sort at different levels along the axis, but they give no certain 

 information concerning their nature: that problem will be con- 

 sidered later. 



