W. F. Bewley and W. Buddin 



17 



Table 11. 



Table showing the liniits tvithin ivhich the death-point lies expressed as 

 parts per 100,000 of chemical in the water suspension {all liquids were 

 measured by volume and solids by iveight). 



Mercuric elilorido 

 "ChloDos*" 



Formaldehyde 



Formic acid 



Potassium permanganate 

 Copper sulphate 

 Ammonium polysulphide solu- 

 tion, 1919 



Phenol ... 



Sulphuric acid ... 



Calcium bisulphite iolution ... 



Potassium sulphide 



Acetic acid 



Ferric chloride ... 



Ferrous sulphate 



Zinc chloride ... 



Hexamine 



Potassium sulphate ... 



Potassium biphosjihate 



Sodium carbonate 



Sodium formate 



Sodium nitrate 



Temperature to \\hich water 

 must be raised to kill my- 

 celium and "summer" spores 



Phytophthora 



parasiti(!ii 



Mycelium 



and conidia 



5-20 

 25-50 

 10-50 

 10-50 

 40-100 

 10-50 



100-300 

 300-500 

 100-500 

 300-1000 



over 2000 

 100-200 

 50-2000 



over 2000 

 „ 3000 

 „ 3000 

 „ 3000 

 „ 5000 

 „ 5000 

 „ 5000 

 „ 10000 



Phytophthora 

 cryptogea 

 Mycelium 



5-20 

 20-50 



5-50 

 10-50 

 40-100 

 10-40 



100-200 

 300-500 

 5-30 

 300-1000 



1000-2000 

 50-200 

 50-200 



over 2000 

 „ 3000 

 „ 3000 

 „ 3000 

 „ 5000 



1500-5000 



over 5000 

 „ 10000 



60° C. 50° C. 



Proprietary solution. 



Colletotrichum 



oligochaetum 



Spores 



0-5-1 



1-5 



50-70 



10-50 



5-350 



10-40 



10-30 

 70-200 

 100-500 

 100-300 

 10-50 

 50-200 

 600-2000 

 over 2000 

 3000 

 3000 

 3000 

 5000 

 5000 

 5000 

 10000 



60° C. 



Clado- 

 sporium 

 fulvum 

 Spores 



1-2 



35-50 

 100-300 

 50-200 

 10-500 

 40-100 



10-30 

 70-200 

 500-2000 

 100-300 

 50-200 

 200-300 

 600-2000 

 over 2000 

 3000 

 3000 

 3000 

 5000 

 5000 

 5000 

 10000 



70° C. 



second number the concentration which is completely toxic. Thus five 

 parts in 100,000 mercuric chloride retards the growth of Phytophthora 

 parasitica, while 10 parts in 100,000 kills the spores and mycelium. 

 Where "over 2000" appears in a column, it indicates that the number 

 following "over" is the lowest concentration which shows any toxic 

 effect. The final lethal concentration in these cases is too high for prac- 

 tical purposes and has not been determined. The compounds are arranged 

 in order of relative toxicity; the most effective ones appearing at the 

 top of the list. It must be understood that the concentrations given are 

 toxic only to the vegetative and thin- walled spores of the fungi employed, 

 and not to the thick-walled resting spores. Thus, while they may not 

 completely rid the water of its infections, they practically do so by 

 Ann. Biol, vm 2 



