ASEXUAL CYCLE OF PLANARIA VELATA. 



TABLE VI. 



4. The Frequency of Encysiment in Pieces in Relation to Age. 



In the very small young worms recently emerged from cysts 

 pieces, unless very small, usually reproduce whole worms with- 

 out going through a period of encystment. As the worms in- 

 crease in size and become physiologically older the frequency of 

 encystment increases until in worms which are almost ready to 

 fragment and encyst naturally all pieces resulting from section 

 usually encyst. 



The differences in this respect between half grown worms, 

 worms which are about full grown but have not yet ceased to 

 feed and still retain their dark color and worms which have 

 stopped feeding and become gray in color are shown in the three 

 series following. 



Series 47, September 21, IQII. Twenty worms about half 

 grown (7 mm. in length) w r ere cut into four equal pieces, a-d. 

 The percentages of regulation without encystment and of en- 

 cystments appear in Table VII. 



TABLE VII. 



