504 SUMMARY OF CURRENT RESEARCHES RELATING TO 



B. coli as the cause of a very destructive bud-rot of the cocoauut is 

 especially interesting. One is loath to accept the conclusion, but the 

 work upon which it is based is well done. The experimental evidence 

 is that the bud-rot organism is in all ways indistinguishable from animal 

 B. coli, and that B. coli from animals will cause the typical rot. 



P. citri is one of the latest to attract attention as the cause of the 

 very serious Citrus canker which bids fair to make destructive inroads 

 upon fruit culture in the Gulf States. 



A group of diseases of distinct type, the " wilts " are found to be 

 largely bacterial and are due to a plugging or embolism brought about 

 by the growth of bacteria within the vessels of the plant. Infection 

 has been shown to occur in a variety of ways, notably through wounds 

 which break down the outer protective plant coverings, or through 

 natural openings such as stomata, water-pores or nectaries. Apart 

 from the important role played by insects in the transmission of plant 

 diseases, surface soil water is in some cases responsible for extensive 

 distribution of the parasite. Continued growth and multiplicatiou of 

 parasitic bacteria in the fallen plant parts, or even in the manure pile, 

 offer an additional explanation of disease dispersal in some instances. 

 In other cases it has been demonstrated that the causal bacteria remain 

 alive upon the outside of the seed-coats and thus lead to infection of 

 the ensuing crop. 



Action of Bacillus fluorescens liquefaciens on Asparagin.* — 

 A. Blanchetiere finds that Bacillus fluorescens liqtiefaciens flourishes on a 

 medium in which the sole source of carbon and nitrogen is asparagin. 

 This medium is particularly favourable to the production of pigment. 

 After a cultivation of suitable length, about 90 p.c. of the total nitrogen 

 is converted into ammonia, and after a further lapse of time part of this 

 nitrogen undergoes a retrograde metamorphosis. 



Fermentable sugars have a retarding action if the medium be 

 rendered alkaline by the addition of calcium carbonate. If the saccharated 

 media be acidified, hydrolysis of the nitrogenous groups is limited to the 

 amido group, and the hydrolysis is much retarded. The manner in 

 which asparagin behaves alone or in the piresence of sugars and of 

 ammonia salts leads us to think that the attack on the aspartic molecule 

 when alone is not due to a necessity of microbic development. This 

 molecule is attacked as strongly in the presence of sources of energy 

 more easy to utilize when the chemical conditions necessary to the action 

 of ferments are realizable. 



* Ann. Inst. Pasteur, xxxi. (1917) pp. 291-312. 



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