No. 4.] 



PLA NA RIA MA CULA TA . 



203 



found where the eyes either divided, or became abnormally 

 large and irregular in shape, and two where the pharynges 

 developed abnormal proportions. 



The first case was caused by an operation upon a planarian 

 to produce a bud, as indicated in Fig. 6. Three times the bud 

 divided off by fission, leaving the worm almost normal in ap- 

 pearance. After the third operation the eyes, which were cres- 

 centric in outline, began to deposit pigment in the concavity in 

 irregular masses until the condition represented in Fig. 17 was 

 produced, when the head separated from the body by fission. 



The second case (Fig. 18) is that of a worm which had been 

 operated on in a similar manner. The bud divided off and 



FIG. 17. 



FIG. is. 



FIG. 



FIG. 17. A worm in which the eyes have become abnormally large after being operated on. 

 FIG. 18. A worm in which two new eyes developed after an operation upon its sides. 

 FIG. 19. The dark part of the right eye divided after operation on the side of the worm. 



almost immediately the eyes divided, giving four eyes. The 

 one on the extreme left side of the head has the concavity on 

 the right side, suggesting the possibility of its functioning as a 

 right eye. Two others are in almost the normal position, 

 while the fourth lies between them and a little to the left of 

 the middle line of the head. 



The third case (Fig. 19) is that of a worm which had been 

 operated on in the posterior part of the body on the left side, 

 producing a bud. When the bud had become half grown it 

 divided near its anterior end. The right eye of the worm then 

 divided in such a way as to produce two, one lying just anterior 

 to the other. The head of this animal also separated from its 

 body by fission soon after the division of the eye. 



The two cases of abnormally developed pharynges were 



