118 



C. M. CHILD 



n 



Figs. 14 to 17 Effect of different concentrations of alcohol: pieces include 

 region anterior to level 1 in figure 1. Figure 14, water. Figure 15, 0.5 per cent 

 alcohol. Figure 16, 1 per cent alcohol. Figure 17, 2 per cent alcohol. 



but the pharynx has developed and intestinal regulation in the 

 pharyngeal region has begun. 



In figure 17 a piece after five days in 2 per cent alcohol is shown. 

 All regulation except closure of the wound is inhibited. This is 

 the only one of the five pieces that lived five days. 



These series show that the formation of a pharynx and of the 

 lateral intestinal branches in the pharyngeal region may occur 

 under conditions which completely inhibit the formation of a 

 structurally differentiated, functional tail. 



The records of numerous other alcohol series might be given, but 

 all are of essentially the same character. Everywhere the process 

 of tail-formation is inhibited by less extreme conditions than 

 those necessary for inhibition of the processes characteristic of 

 more anterior levels. The process of pharynx-formation shows a 

 greater resistance to alcohol than that of tail-formation, but less 

 than that of head-formation. In pieces from different levels, 

 on the other hand, the same regulatory process is differently 

 affected by the same concentration of alcohol. All the results 

 obtained along this line with alcohol point to the existence of a 

 dynamic axial gradient in the original worm and in the piece. 



h. Ether. The results obtained with 0.4 to 0.5 per cent ether 

 are in general similar to those described above for alcohol. The 

 same differences appear along the axis in the effect of the ether 

 upon the regulatory processes. Ether inhibits the outgrowth of 

 new tissue to a somewhat greater extent than alcohol so that 



