4o6 



The Ohio Naturalist. 



[Vol. IX, No. 2, 



Table I. 



Date— February 27, to March 15, 1908. 



The illustrations (Figs. 1-4) \vhich are reproduced from 

 photographs of plants that had been regenerating about 8 days 

 after the epicotyls were cut off, will serve for comparing the 

 actual sizes attained by the different plants. Reading from left 

 to right the arrangement of the cultures in the photographs is 

 in all cases as follows: control, solutions a, b,c. From these figures 

 it will be seen that the rate of regeneration varies l)Oth with the 

 nature of the medium and also with the strength of the solution 

 in Avhich the plants regenerated. In pilocarpine (Fig. 1) the 

 plants developed more luxuriantly than the controls and the 

 greatest acceleration is shown in both the stronger and the 

 weaker solution (0.01% and 0.001%). In solutions of digitalin 

 (Fig. 2) the greatest acceleration took place in the weaker solu- 

 tion, while the regeneration was slower in the strong solution 

 (0.01%). Atropine (Fig. o) and strychnine act as stimuli only in 

 verv weak solutions (0.0001%). In extremely attenuated solu- 



