. Bacteria in relation to plant diseases. Bacteriology; Plant diseases. 346 BACTERIA IN RELATION TO PLANT DISEASES. This organism does not produce acids in milk, but there is a slowly increasing alka- linity, and after some days (3 to lo or more) the casein is precipitated as a finely divided, voluminous, mobile mass, which settles slowly. These phenomena are best observed in litmus-milk. The litmus in such cultures is slowly reduced, but on the death of the organism it is oxydized back into a deep blue. In the end the casein is partially peptonized, but this change does not occur rapidly. The
. Bacteria in relation to plant diseases. Bacteriology; Plant diseases. 346 BACTERIA IN RELATION TO PLANT DISEASES. This organism does not produce acids in milk, but there is a slowly increasing alka- linity, and after some days (3 to lo or more) the casein is precipitated as a finely divided, voluminous, mobile mass, which settles slowly. These phenomena are best observed in litmus-milk. The litmus in such cultures is slowly reduced, but on the death of the organism it is oxydized back into a deep blue. In the end the casein is partially peptonized, but this change does not occur rapidly. The organism makes a good growth in milk and forms a bright yellow rim (plate 20, figs. 2-4), and sometimes a pellicle. In old cultures sheaf- like crystals of tyrosin occur. In April, 1898, two 10 cc. tubes of milk, which had received 4 steamings and been under observation for a month unchanged, received 200 mgs. each of thymol. One was put away as a check, the other received 8 cc. of whey from a milk-culture of Bad. hyacinthi t,t, days old, after this had been heated in the water bath for 10 minutes at ° C. (4° above the thermal death point). There was no change in the check tube. In the other, there was copious precipitation of the casein in 48 hours, but no evidence of bacterial growth either then or subsequently (ii clays). In (Jctober, 1898, the experiment was repeated with the same result. In this experiment (fig. 143) 10 cc. of sterile milk received 3 cc. of whey from a milk-culture 10 days old. One hour after adding the whey the tube was heated for 20 minutes at 52°C. in the water bath to destroy the bacteria. In 24 hours the milk was entireh^ coagulated. A small drop from this tube was now transferred to bouillon but did not cloud it (5 days). At the same time another tube of the same milk received 3 cc. of whey from an- other milk-culture of the same organism, the only difference being that in this case the milk was heated for 10 minutes at 8o°C. after adding th
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