NOTES ON THE PHYSIOLOGY OF REGEN- 

 ERATION OF PARTS IN PLANARIA 

 MACULATA. 1 



C. C. LEMON. 



I. JTodes of Regeneration. 



In Planaria maculata there are two methods of inducing 

 regeneration. First, isolated parts of sufficient size taken 

 from any part of the body except the region in front of the 

 eyes will regenerate ; and second, partly isolated areas may 

 regenerate, producing compound planarians. 



i. Isolated Parts. -- Randolph, 2 1897, states that when a 

 worm was cut into eight pieces by cross cuts, seven of them lived, 

 and six of them regenerated all lost parts. The seventh failed 

 to regenerate eyes. 



Morgan 3 has shown that there is a limit of size below which 

 regeneration of lost parts will not take place. He also thinks 

 that while the area in front of the eyes, which does not regen- 

 erate, is near this lower limit of size, there is another cause, 

 probably that of greater specialization, why it will not regen- 

 erate lost organs. 



My own observations on regeneration of isolated parts, 

 though limited, for the most part support those of Morgan, as 

 will be seen from the following record of experiments. A 

 worm 10 mm. long and 2 mm. to 3 mm. in width was cut into 



1 The work herein recorded was done in the Laboratory of Experimental 

 Morphology of Michigan University, under the direction of Dr. F. R. Lillie, to 

 whom the writer wishes to express his sincere thanks for assistance and encourage- 

 ment. 



2 " Observations and Experiments on Regeneration in Flanarians," Separat- 

 Abdruck aus dem Archiv fiir Entwickelungsmechanik der Organismen. Bd. v, 

 p. 355. 1897. 



3 " Experimental Studies of the Regeneration of Planaria maculata," Separat- 

 Abdruck aus dem Archiv fur Entioickelungsmeckanik der Organismen. Bd. vii, 



PP- 365-372. 1898. 



'93 



