REGENERATION IN PLANARIAN PHAGOCATA GRACILIS. 163 



(ii.) has no old pharynges ; but two new ones, one of which is 

 the central pharynx, (iii.) has no old lateral pharynges in the 

 posterior part, three new anterior ones, including a new central 

 pharynx. Each of the tail-pieces has one new pharynx ; (ii.) has 

 also one lateral pharynx-bud. 



In another series (B) the planarians, cut into ten pieces, were 

 kept ten days before being killed. 



(a) The head-pieces died with but one exception. In this a 

 pharynx cavity is formed with, possibly, a pharynx-bud. 



($) The second pieces except worm (ii.) show new pharynges 

 regenerated. 



(iii.) and (iv.) have developed a new central and four new lat- 

 eral pharynges. 



(i.) has a central and three lateral pharynges. 



(r) The third pieces all have a new central pharynx and from 

 one to three new lateral ones. In one piece the anterior pharynx 

 is probably the old one. 



(c^) The fourth pieces show new pharynges regenerated at 

 at each end of the pharynx cavity, there being old ones in the 

 middle, (i.) and (iii.) have a new central pharynx and several 

 new lateral posterior ones, and several old ones in the middle. 



(ii.) differs in having other new pharynges besides the central 

 one in the anterior part. 



(e) The fifth pieces are similar to the fourth, having new pha- 

 rynges at both ends, old ones in the middle. 



(/") Two of the sixth pieces have four new lateral pharynges 

 posteriorly, the central one and the three anterior lateral ones 

 being old. 



(iii.) has a central and two lateral pharynges, probably all of 

 them new. 



(g) All of the seventh pieces have a new central pharynx, old 

 ones in the middle and new ones towards the posterior end. 



(/;) One worm of the eighth set shows a condition similar to 

 those of the seventh set. The other has only new pharynges, 

 a central and two lateral ones. 



(/) The ninth pieces have two or three new pharynges, (i.) has 

 a central one, while in (ii.) no central pharynx has regenerated. 

 No old ones are left. 



