ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 247 



dilution of a specific anti-cholera serum was found to be a true cholera 

 vibrio, whereas no other vibrios agglutinated in a weaker dilution than 

 1 : 10. Four cholera vibrios did not agglutinate in certain sera in 

 higher dilution than 1 : 200, and three of these, as it happened, had 

 been travelling for seven days in mixed cultures. 



The third point was whether El Tor vibrios were to be found in the 

 Philippines. For this purpose Buffer's haernolytic test was used. Ruffer 

 found that El Tor vibrios had the power of lysing suspensions of red 

 corpuscles, and that cholera vibrios had not this property. The authors 

 found that none of their agglutinating strains were haernolytic, and so 

 report that they have not discovered El Tor vibrios in these islands. 



In settlement of the fourth point, they found that none of the 

 cholera-like strains which did not agglutinate with a specific serum 

 could be made to acquire such agglutinability. 



Fifthly, they found Dieudonne's medium satisfactory as a means of 

 isolating cholera vibrios from the stools, but it could not be used for 

 differentiating cholera-like vibrios from true vibrios. 



Lastly, they performed a few experiments in order to find whether 

 the hog might be a cholera carrier. The results were negative. 



Bacterial Disease of Potato-plant.* — G. H. Pethybridge and P. A. 

 Murphy give an account of a disease occurring among potatoes in Ireland, 

 from which a specific organism has been isolated. The most obvious 

 features of the disease consist in discoloration and drying of the foliage, 

 browning of the principal vascular bundles of the stem, decay of the 

 underground part of the stalk, and rotting of the tubers. An organism 

 was isolated, which was inoculated into healthy plants, and thus shown 

 capable of reproducing the disease. It is a multiflagellate, peritrichous- 

 bacillus, liquefying gelatin, practically non-chromogenic, and evidently 

 allied to, but not identical with, certain other organisms which have 

 been described in other countries as causing a similar disease in potatoes. 

 The name Bacillus melanogenes has been suggested. Preventive measures- 

 should aim at the destruction of diseased plants, the exclusion of affected 

 tubers from the pits, and the procuring of tubers for seed purposes from 

 crops in which the disease has not appeared. 



* Proc. Roy. Irish Acad., xxix. (1911) pp. 1-37. 



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