102 James Small on 



suggestions have been put forward tentatively^, as a working 

 hypothesis which may open up this particular field to experimental 

 investigations. 



Any apical meristem is considered as generating an electric 

 current. The apical meristem of the stem produces a sym- 

 metrically flowing ' normal polarity current " as previously 

 described. The primordial knob which develops into a leaf starts 

 as a slight more or less hemispherical swelling near the stem 

 apex ; then it develops a meristematic region and grows out to 

 form a leaf. The young leaves developed in this way overlap the 

 comparatively small apex of the main axis of the stem. 



The electric fields of the currents produced by the growing 

 points (meristems) of the leaves and of the stem may be compared 

 with the magnetic fields of magnets. The electric field of the 

 stem current is small, compared with that of the larger leaf 

 current. The stem is represented by a small cylindrical magnet 

 placed vertically, and the leaf is represented by the opposite pole 

 of a large bar magnet placed horizontally. If the combined 

 magnetic fields are investigated by means of iron filings, when 

 the large magnet is set close to the top (opposite pole) of the 

 smaller magnet, a small neutral area will be found to be induced 

 on the side of the "axis " opposite to the large magnet. 



Now, if normal polarity of growth is due to the normal 

 polarity current, the cells in this neutral area will be freed from 

 that influence and will grow in all directions. Such growth would 

 give rise to the first stage of the leaf as a primordial knob. 

 When growth advanced further and a meristem developed, an 

 electric current and its electric field would result. Meanwhile 

 the first leaf would be carried away from the stem apex by the 

 elongation of the stem, and the new leaf (originated by the effect 

 of the electric field of the first leaf on the normal polarity current 

 at the stem apex) would be left to help in the development of 

 the primordial knob of a third leaf, and so on. 



1 New Phytologist. Vol. XIX, p. 210. 1920. 



