NOTES ON RECENT RESEARCH. 



G89 



Heterodera radicicola. A healthy and normal plant was planted in soil in 

 which an infested plant of the same kind and showing petalody had been 

 growing. The following year the healthy plant showed the galls of the 

 eelworm on the roots, also petalody of the stamens or double flowers. 



For the formation of double flowers the author considers that the 

 horticulturist should foster the association of parasites with cultivated 

 plants, as double flowers are produced by such an association in nature. 



G. M. 



Electricity in Seeds. 



Electrical Reactions of Plants. By Dr. Arthur Tompa {Beih. 

 Bot. Cent. bd. xii. ht. 1, p. 98).— The author has conducted a series of 

 experiments on seeds on similar lines to those of Dr. Augustus Waller. 

 This paper contains a record of his results and a short bibliography. His 

 results may be summarised as follows : — Electric polarisation appear- 

 ances can be produced with dead as well as with living seeds. The 

 polarisation currents are of considerable intensity, but are of very low 

 tension (Spawning). Changes in the inner resistances of the seed alter 

 both the intensity and also the direction of the current. The strength 

 of the current which can be induced by mechanical injury (on the out- 

 side) seems to depend on changes in the inner resistances, for they show 

 no measurable electromotive strength. The direction of the current also 

 depends on these resistance changes, and the electrode which lies next the 

 place stimulated becomes the anode. Living seeds produce electromotor 

 strengths of which the potentials are over 0*005 volt. Dead seeds show 

 either no potential, or it is less than 0*005 volt, and generally less than 

 0*002 volt. 



A lesion current with a potential over 0*005 volt is to be taken as a 

 sign of life in seeds. Lesion currents appear to originate in the embryo 

 (especially in the hypocotyledonary part) of living seeds (not germinated). 

 They are of higher potential than the electromotor strengths present in 

 uninjured seeds 



In dicotyledons the current is from the embryo to the point stimu- 

 lated, and in the reverse direction in monocotyledonous (Grass) seeds. 

 (See also ' Plant Juices.') — G. F. S.-F. 



Electricity Compared in Animal and Vegetable Life. 



Electric Response in Ordinary Plants under Mechanical 

 Stimulus. By J..C. Bose (Joum. Linn. Soc, Bot. vol. xxxv. p. 275 : 

 July 21, 1902.) — An account is given of various experiments which the 

 author made to determine, to use his own words, " If throughout the 

 whole range of response phenomena a parallelism between animal and 

 vegetable could not be detected. That is to say, I desired to know, with 

 regard to plants, what was the relationship between the intensity of 

 stimulus and the corresponding response ; what were the effects of super- 

 position of stimuli ; whether fatigue was present, and in what manner it 

 affected the response ; what were the effects of extremes of temperature 

 on the response ; whether chemical reagents could exercise any in- 

 fluence on the plant-response, as anaesthetics and poisonous drugs have 

 been found to do with nerve and muscle ; finally, if it could be proved 



Y 



