Studies on Regulation. 



533 



of the pieces ten days later is indicated in Figs. 45, 46 and 47. 

 In spite of the fact that there was no trace of any physical obstacle 

 to growth, such as Schultz believes the closure of the cut surface 

 constitutes, little regeneration has occurred. The condition of 

 the pieces a month after the second operation is indicated in Figs. 

 48, 49 and 50. The new tissue has increased slightly in amount 

 but although there is no union of the old muscular layers on the 



cut surface no head has been formed. After another month no 

 further change except reduction in size had occurred. 



Series 76. Five posterior pieces were obtained by a transverse 

 cut through the middle of the pharyngeal region. Eight days 

 after section all resembled Fig. 51, the contraction of the cut sur- 

 face being in some cases somewhat greater, in others less. At 

 this time the anterior part of the contracted lateral regions was 

 removed in the manner indicated by the lines in Fig. 51. 



Figs. 52, 53 and 54 represent the condition of the pieces ten 

 days after the second operation. The double outgrowth in Fig. 



