362 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. 



Each of the tubes to be tested had 5 c.c. of the copper sulphate solu- 

 tion and was sterilized on three successive days. There were three 

 tubes of each of the preceding dilutions as well as three check tubes 

 of distilled water. Each of the tubes was inoculated with three loopfuls 

 of a walnut blight culture grown in Dunham solution for forty-eight 

 hours. The loop of needle was 2 mm. in diameter. Three hours after 

 being inoculated dilution plates were made from each of the tubes under 

 experiment by transferring three loopfuls of the inoculated germicidal 

 tube to meat peptone agar. These plates constituted series I of the 

 experiment. After six hours from inoculation of tubes containing the 

 germicide a second plating out from the tubes was made in the same 

 manner as the first. 



The results after seven days' growth in the Petri plates showed that 

 no growth resulted in the plates of series I made from 1/100 per cent, 

 1/500 per cent, 1/1000 per cent or 1/2500 per cent copper sulphate. 

 In the check tubes as well as in the 1/5000 per cent, a large number of 

 colonies developed. 



The three plates made from the 1/5000 per cent had 8, 30 and 60 

 walnut blight colonies, while the two check plates had 200 and 225 

 blight colonies, and the third plate had a spreading, white, foreign 

 organism that covered the entire surface of plate and covered up the 

 walnut blight growth. 



In series II, plated out after six hours' incubation, no growth 

 occurred during seven days. 



Another experiment made earlier in the study gave almost the same 

 results. The 1/100 per cent, 1/500 per cent and 1/1000 per cent killed 

 the organism, while the 1/5000 per cent failed to do so. No test was 

 made of the 1/2500 per cent in this experiment. The per cent of 

 copper sulphate sufficient to kill is somewhere between 1/2500 and 

 1/5000 per cent. 



Mercuric Bichloride (corrosive sublimate). The same general 

 method was employed as with copper sulphate. Four tubes each of 

 the following strengths were used in distilled water : 1/100 per cent, 

 1/500 per cent, 1/1000 per cent, 1/5000 per cent, and 1/10000 per 

 cent and two check tubes of distilled water. All were sterilized and 

 then inoculated with four loopfuls of a 24-hour growth of the organism 

 in meat bouillon. In four hours from inoculation, plates were made 

 from each tube. After six days' time no growth developed in any but 

 the check plates and these showed 41, 48 and 150 colonies each. 



Another experiment with corrosive sublimate, using more dilute 

 strength in distilled water, was made. Three tubes of each of the 

 following strengths were tested: 1/1000 per cent, 1/10000 per cent, 

 1/50000 per cent, 1/100000 per cent, 1/500000 per cent, and 1/1000000 



