418 S. SAWA. POISONOUS ACTION' OF POTAS. PERSULPHATE. 



It seemed to me of interest to test the effect of a still higher 

 dilution. Accordingly young Cuatrbita plants of about 6 cm. 

 length [with 3 leaves were placed April 22nd in a o. 1 per mille 

 solution of potassium persulphate containing all the mineral 

 nutrients in the form of Knop" s solution ; but even in this case 

 after two weeks some leaves had become curled and yellowish. 1 



We must infer therefore that potassium persulphate shows 

 considerable poisonous effects upon phaenogams. 



> Compounds which may not be stimubnts in a certain dilution ior phaenogams 

 may however be stimulants for fungi. Thus H. Hattori (Journ. College of Science, 

 Tokyo, 1901) observed that copper sulphate injures the growth of roots of the pea and 

 maize even at 0.000001% while at 0.004% >t stimulates the growth of fungi. 



