28 HATCH EXPEKL^H:NT STATION. [Jan. 



ulating plants would i)r()duco little efiect on the soil ; at any 

 rate, it would i)roducc little effect during the short space of 

 time it requires to mature most crops. Moreover, when it 

 is considered that moist seeds and seedlings respond to elec- 

 trical stimuli in quite a remarkable manner when sown and 

 allowed to develop on moist filter-paper cloth or in porous 

 clay dishes, etc., the complicated soil theory of electrical 

 action falls to the ground. 



Electricity affects the protoplasm of the plant, and it is 

 to the effect on the protoplasm that we must look for the 

 solution of the problem, and not to its influence on the soil. 

 This can be seen in plants that show protoplasm movements, 

 such as Chara, etc. It has long been known that weak 

 currents stimulate protoplasm, and induce an accelerated 

 movement ; Avhereas strong currents retard or stop such 

 movements, or, if too strong, they kill the protoplasm. 



Current electricity likewise induces bendings in the roots 

 (galvanotropism) when grown in Avater betAveen electrodes. 

 In such cases weak currents produce negative bendings, — 

 that is, towards the cathode ; while strong currents produce 

 positive bendings, — towards the anode. Similar effects are 

 seen in the movements exhibited by many microscopic ani- 

 mals, such as paramoecia and other protozoa. 



Plants respond to light, gravity, moisture, etc., in a posi- 

 tive and negative manner ; and it is also known that a 

 negative electrotropic irritability exists in certain })lants 

 (Phycomyces in this case), or a sensitiveness to Hertz waves 

 which induces negative bendings. The plant organism, 

 whether in the embryonic or adult stage, responds in a posi- 

 tive and negative manner to various cosmic forces which act 

 as stimuli. There is a positive geotropism which induces 

 roots to grow downwards, and a negative geotropism which 

 induces shoots to grow upwards. The force which accom- 

 plishes this is termed gravity. Our comprehension of grav- 

 ity, however, is scarcely more intelligible than that of 

 electricity, and for all we kno\y they may be the same or 

 similar manifestations of force. The results of electrical 

 stinmlation to plants are quite similar in their effects to 

 those exhibited by other forms of stimuli. 



