288 REPORTS ON THE STATE OF SCIENCE. 



3. The rate of intoxication of a muscle by an anaesthetic is a 

 function of the temperature at which the intoxication takes place. 



4. The rate of evolution of hydrocyanic acid by a laurel leaf is a 

 function of the temperature at which it takes place. 



5. A method has been elaborated by which it is possible to measure 

 the output of HCN by a laurel leaf during a period of one minute. The 

 output has been found to be, e.g., O'l milligramme per gramme per 

 minute at 40° and 0-01 at 20°. 



6. The method is applicable quantitatively as well as qualitatively 

 to any vegetable and animal tissue. 



7. By means of this method the distribution of a cyanide in the 

 body of a poisoned animal and of man can be conveniently determined. 



8. The organs in which a poisonous cyanide is found post-mortem 

 in greatest relative amount are the heart and the brain. It is found 

 in smallest relative amount in skeletal muscle. 



APPENDIX. 



On the Blaze Currents of Laurel Leaves in relation to their Evolution 

 of Prussic Acid. By Mrs. A. M. Waller. 



The presence of a ' blaze current '* is a sign that the plant or animal 

 tissue is living and also how much it is alive (Waller). A young laurel 

 leaf kept in a moist tube from May 26 to June 9, and tested occasionally, 

 continued to give the blaze current quite normally. On May 26 its 

 blaze was 0.0150 volt, and on June 9 it was 0.0080 volt. During the 

 whole time it gave off no hydrocyanic acid, as shown by the absence of 

 discoloration of picrate of soda test-papers (Guignard). 



There are different types of blaze currents, each part of an animal 

 or plant having its definite and normal type. The type of blaze current 

 is studied by means of Waller's ABC 2 method. In a laurel leaf, 

 as in all other leaves, the blaze runs from external to internal surface. 



All leaves hitherto tested have given the same type of blaze current. 

 In response to excitation the blaze generally runs from the upper to 

 the under surface, whereas in petals of flowers it runs ' homodrome ' 

 in the same direction as the exciting current. The blaze current runs 

 from the growing point in stems towards more quiescent parts. 



The blaze current is entirely a local phenomenon, and is confined 

 to the exact area excited. A lilac leaf (chosen on account of its 

 greater permeability and its lower resistance as compared with laurel 

 leaves) which gave a blaze of 0.0300 volt was submitted to chloroform 

 vapour by placing over part of its surface for one minute a watch glass 

 on the under surface of which was stuck a piece of filter paper soaked 

 in chloroform. The blaze was abolished at this spot, but was produced 

 as before at other parts of the leaf. The exposure of such a leaf for 

 one minute to air saturated with chloroform vapour is sufficient to kill 

 the leaf, but it takes a longer time to kill a leaf immersed in a liquid 

 saturated with chloroform. 



1 A. D. Waller, Trans. Roy. Soc, vol. 194, B. 1901, p. 183. 

 9 A. D. Waller, Signs of Life, 1903. John Murray, London. 



