146 THE BOTANICAL MAGAZINE. [Vol. xxi. No. 250. 



From the facts that any organic as well as inorganic neutral 

 salt of alkali metals, alkaline earths or magnesium group tested 

 at various concentrations shows no attraction 1 ^ and that several 

 basic substances — hydroxide and basic salts — exercise repulsion 

 according to the alkalicity of the solution, it follows, in esti- 

 mating the attraction of acidic substances, that we must at- 

 tribute the attraction to the ion H and the repulsion to the ion 

 OH. This conclusion would be evident should we take, for 

 instance, IIC1, XaCl and NaOII for comparison. These are 

 easily dissociable substances and at dilute solutions remain 

 the least undissociated molecules, so that the action must be 

 exerted by the existing ions. Na and CI ions being ascertained 

 to be indifferent, the active components in the solution of HC1 

 and NaOH should be H-and OH-ions respectively. 



Glycerin, urea, cane sugar, grape sugar, milk sugar and 

 pepton are inactive while coloroform and chloralhydrate, both 

 of which are injurious, show somewhat repulsion. Copper 

 sulphate and mercuric chloride being strong poisons, seem to 

 act also repulsively. 



When a capillary tube with concentrated solution of acids, 

 1 mol 2 for instance, is inserted under the cover glass under 

 which the swarm-spores of Aethaliunr" swim about actively, we 

 observe within 5-10 minutes an apparent reaction of the spores 

 relatively to the acids. The acidity being too strong, they 

 are inhibited to approach near the mouth of the tube so that 

 all attracted spores assemble at a certain equal distance from 

 the mouth so as to form a complete ring. Instances of ring- 

 collections of other organisms were enumerated in Rothert's 

 paper. ,; I alike them, however, Myxomycetes forms so remark- 



1 With Stemonitia a slight lui t apparent collection was often observed near or 

 :it the month of a tube filled with calcium nitrate, potassium sulphate, zinc sulphate, 

 sodium chloride or calcium chloride, not so remarkable, however, as with free acids. 

 ial and further investigation i~ required on this point. 

 '•> One mol dissolved in one litre of water. 



Qnlese otherwise -aid all the following experiments were done with Aethalium. 

 « Rothebt, Flora 88. 1901. p.371. 



