INFLUENCE OF MAGNETISM AND ELECTRICITY ON GROWTH 107 



probably due to the use of stronger currents, which always injure and 

 ultimately kill the plant. 



Electrical currents of high potential and short duration, such as single 

 or alternating induction shocks or discharges, act primarily like mechanical 

 disturbances or shocks, and hence produce certain irritable responses, and 

 when intense exert injurious or fatal effects 1 . Possibly an intermediate 

 intensity of stimulation might, as in other cases, slightly accelerate growth, 

 as well as respiration and other forms of vital activity. 



Growth does not seem to be affected even in the strong magnetic 

 fields used by Cisielski and Reinke 2 , although G. Tolomei 3 states that 

 a certain acceleration of germination is produced in strong magnetic fields. 

 Errera 4 observed no influence of magnetism upon cell-division or nuclear 

 division, and Reinke 5 found that protoplasmic streaming was unaffected. 

 [A pronounced secondary effect is, however, produced after prolonged 

 exposure as the result of inductive action 6 . Since of the different con- 

 stituents of the cell some (cellulose, albumen, chlorophyll) are paramagnetic 

 in air and are attracted by magnets, whereas others (starch, sugar, oil, 

 water) are diamagnetic and are repelled, it is theoretically only necessary to 

 obtain sufficiently strong fields to produce all the internal stimulatory effects 

 of which gravity and centrifugal force are capable, for these are undoubtedly 

 due to the different densities of the constituents of the living cells, and if 

 these were all alike no perception of such stimuli would be possible. This 

 of course leaves out of question the mechanical stresses and strains due to 

 the mass-attraction upon the entire organism ; but that geotropism, for 

 example, is not due to any such action is at once shown by the fact that 

 roots still grow downwards in media of the same or of even greater density. 

 As a matter of fact, however, the required magnetic intensities are probably 

 incapable of attainment 7 .] 



Ill, p. 141. See also Fliigge, Mikroorganismen, 1896, 3. Aufl., Bd. I, p. 445; J. M Oiler, Centralbl. 

 f. Bact., 1897, 2. Abth., Bd. in, p. no.] 



1 Experiments of this kind were performed by v. Humboldt (see Ingenhousz, Ernahrung d. 

 Pflanzen, 1798^.42). The older literature is given by Treviranus, Physiologic, Bd. n, p. 709 ; 

 de Candolle, Physiol. ve"getale, T. in, p. 1088; Nobbe, Samenkunde, 1876, p. 252. 



2 Cisielski, Cohn's Beitr. z. Biol., 1872, Bd. I, 2, p. 6 ; Reinke, Bot. Ztg., 1876, p. 133. 

 Negative results have also been obtained with animals by Hermann (Pfliiger's Archiv f. Physiol., 

 1888, Bd. XLIII, p. 228). 



3 Tolomei, Bot. Jahresb., 1893, p. 37. [If small seeds, such as linseed, cress, mustard, turnip, 

 cabbage, or wheat, are allowed to germinate on wet sand or sawdust, just above which a strong 

 electro-magnet is vertically or horizontally suspended, germination is often slightly accelerated in 

 the neighbourhood of the magnet. The same effect may, however, be produced when the magnet 

 is not excited or when a bar of soft iron is laid across its poles. It is in fact merely due to the 

 influence of the mass of iron upon the distribution of moisture, and is shown when the surrounding 

 air is comparatively dry, but not when it is kept uniformly moist.] 



* Errera, Bull. d. 1. Soc. Bot. d. Belgique, 1890, T. XXIX, p. 17. 



5 Reinke, Pfliiger's Archiv f. Physiol., 1882, Bd. xxvui, p. 140. 



6 Ewart, Proc. of the Royal Society, Jan. 1902, p. 469. 



7 Id., On Protoplasmic Streaming, Clar. Press, 1903, pp. 45, 49. 



