ON ELECTROMOTIVE PHENOMENA IN PLANTS. 



287 



Observation 25 (control). — Woman, aged fifty. Death under chloro- 

 form. Distillates as in Observation 24 of blood, brain, heart, muscle, 

 and viscera gave no marked discoloration, 1 i.e., no sign of HON. 



IO- 6 gr.HCN 

 2000 



1500 

 1000 

 500 



— i 1 — j ■ " 



Mins. 10 



20 



30 



40 



50 



60 



0-60 



2000 



Fig. 4. — Evolution of hydrocyanic acid by a laurel leaf weighing 1*1 grm. in 

 chloroform picrate at 40° ; picrate changed every five minutes. The total 

 amount of HCN evolved was two milligrammes. 



IO- 6 gr.HCN. 

 1200 



1100 



1000 



900 



800 



700 



600 



500 



4O0 



300 



200 



100 



2 4 6 8 10 12 14 16 18 20 



Fig. 5. — Evolution of HCN by two laurel leaves A and B, weighing 0-9 and 12 grm., 

 immersed in chloroform picrate at 40° ; picrate changed every minute. In both 

 cases the portion of curve observed is approximately a straight line rising at a 

 rate of 100 millionths per minute in A, and of 40 in B. In A the first appear- 

 ance of HCN took place in the fourth minute, in B in the fifth minute. 



VII. Summary and Conclusion. 



1. In consequence of the action of chloroform on the leaves of 

 Prunus laurocerasus, the electrical response is abolished within a period 

 of five minutes. The leaves are then dead. 



2. Coincidently with the abolition of the electrical response an 

 evolution of hydrocyanic acid commences. The evolution continues for 

 many hours after death of the leaf. 



1 A faint discoloration, appreciable only by the finer scale, of an approximate 

 value T0 - 2, is obtained with normal tissues. It is probably due to the presence of 

 acetone, as shown by Lieben's iodoform test. 



u 2 



