CONTROL OF HEAD FORMATION IN PLANARIA 

 TABLE lA—Continuefl 



17 



12/18, '20. 16- to 18-mm. worms. Fed three days before cutting 



Control. 



6. M. 1/350. 



7. M. 1/350. 



2 

 6 



2 



10 

 10 

 10 



6 

 6 

 



2/15, '21. 16- to 



18-mm. worms. Fed three days before cutting 



Control. 



8. M. 1/400. 



9. M. 1/400. 



between the A and C pieces indicates some sort of difference in 

 the effect of the chloretone on the factors controUing head for- 

 mation in pieces from these regions. 



If we accept Child's conclusions regarding the effects of KNC 

 on head frequency (p. 8) in A pieces where the stimulation of 

 section is least, the agent may be expected to produce a decrease 

 in head frequency because of its direct inhibition of the X cells. 

 In table lA this result shows quite distinctly in all experiments 

 except series 1 and 3; in both of these the number of deaths in 

 the A pieces completely obscures any effect of the agent on head 

 frequency. 



