122 C. M. CHILD 



With chloretone results of the same general character as those 

 described above for alcohol and ether have been obtained. 



2. Experiments with potassium cyanide 



The cyanides I have found of great value in my attempts to 

 analyze the processes of regulatory morphogenesis. The results, 

 while of the same general character as those obtained with the 

 anesthetics, can be more exactly controlled and the more extreme 

 modifications and inhibitions are readily obtained without the 

 high mortality which accompanies the use of the anesthetics. 



In my experiments with KCN I have used corked Erlenmeyer 

 flasks as described above and have often kept several hundred 

 pieces, fifty in each flask, for two or three weeks inKCN, renewing 

 the solution every forty-eight or ninety-six hours, without losing 

 a single piece, yet the solution was sufficiently concentrated to 

 alter the regulatory capacity of the pieces very greatly. In all 

 such experiments where controls in water are necessary these are 

 also kept in corked flasks, although I have not been able to dis- 

 cover that the results as regards regulation differ whether the 

 pieces are kept in water in corked flasks or in shallow open dishes, 

 provided, of course, that the water in the flasks is changed often 

 enough . 



Here only one of my cyanide series need be given since all 

 points essential to the present purpose are illustrated by it and 

 the results of other series are in general similar. 



Series 409. June 24, 1911. Well fed worms 16 to 20 mm. were 

 used : from these pieces were cut as follows : 



la 2b pieces including the region 1-3 in figure 25 

 Ih 2b pieces including the region 3-5 in figure 25 

 2a 25 pieces including the region 1-2 in figure 25 

 . 2h 25 pieces including the region 2-3 in figure 25 

 2c 25 pieces including the region 3-4 in figure 25 



These pieces were placed in KCN t Woo om in liter flasks, the solu- 

 tion being renewed every four days. Eight days after the begin- 

 ing of the' experiment a rise of several degrees in the temperature 

 of the room occurred and the pieces began to die. Ten days after 



