Mac Dongal, Transmission of impulses in Biophytum. 297 



Transmission of impulses in Biophytum. 



Professor D. T. Mac Dougal. 



University of IMinuesotu. 



Professor Haberlandt lias recently published the results of 

 some observations on Biophytum sensitivum DG. {Oxalis sensitiva 

 L.)^) in wliich lie records the diseoverj of tlie repetition of the 

 reaction movement in response to a single Stimulation. As a 

 result of his work it was found that impulses were transmitted 

 through the midrib of a leaf at a rate of 2,5 to 3 mm per second, 

 through the midnerve of a pinna at a rate of 5 to 1 mm per 

 second, and through the inflorescence at the rate of 1 mm 

 per second. Impulses could be transmitted through girdled 

 midribs but not through sections of that organ killed by hot water, 

 and he therefore concludes that the path of transmission is the 

 parenehyma of the übrovascular bundles, and that the impulse is 

 conducted plasmatically. 



The writer of this note carried on some observations on this 

 subject in the Botanic Institute at Leipzig in 1895 unter the direc- 

 tion of Geh. Rath Prof. Pfeffer, the results of which were published 

 in 1896.^) Although numerous experiraents were made with both 

 Oxalis and Mimosa the discussion was chieflj directed to the 

 results obtained from the latter plant. I find the following 

 references to Oxalis however:^) „I was able to transmit impulses 

 from an incision or flame through dead portions of stems (of 

 Mimosa) 3 cm in length ; in some instances in wliich desiccation 

 had proceeded to such an extent that the cell lumina of the dead 

 portion were devoid of liquid contents, and in one instance through 

 a portion bent at right angles by the weight of the leaf. I was 

 able to obtain similar transmissions in the midrib of Oxalis sensitiva 

 which üffers many of features of Mimosa. In support of this last 

 Paragraph I find the following entries in my notes. June 27. 

 Apical pinnae of leaf in which a middle region 5 mm long had 

 been killed by boiling water on the previous day, snipped with 

 scissors. Impulse transmitted through dead portion, and tive pairs 

 of basal leaflets closed. Air temperature 27 o C. In greenhouse, 

 July 1. Flame and scissor snip applied to apical pinnae of leaf in 

 which a middle portion 1 cm long hed been killed by boiling water 

 an which had desiccated to such extent that the midrib was bent at 

 an angle of 50 degrees. Reaction of nearly normal amplitude in 

 the basal leaflets. Temperature 27 o 0. in experiment room 



*) üeber die Reizbewegungen und die Reizfortpflanzung bei Biophytum 

 sensitivum DC. (Ann. d. Jard. Bot. d. ßuitenzorg. 2nd Supplement. 1898. 

 p. 33.) 



*) The meclianism of movement and transmission of impulses in Mimosa 

 pudica and other ^sensitive plants". (Botanical Gazette. Vol. XXII. 1896. 

 p. -293.) 



■■') 1. c. p. 296. 



