712 SUMMARY OF CURRENT RESEARCHES RELATING TO 



often succumbs to some secondary infection. From observations on the 

 pigeon, the author finds that the disease can only be produced by 

 ingestion, and that although contact is a possible means of infection, it 

 is probably not in this way that natural infection occurs. The virus is 

 especially resistant to drying, but in solution it is readily destroyed. 

 The immunity produced artificially by inoculation of the virus was 

 irregular in its duration ; only the living virus can confer immunity. 

 Sections of the tumours prepared and stained according to various 

 methods, all showed the same appearance of the cell-inclusions, which 

 the author considers are of microbial nature, and not parasitic or pro- 

 ducts of cell-secretion or degeneration formed by the action of some 

 unknown virus ; but the bacterial nature of these inclusions must remain 

 doubtful until cultivations can be obtained. 



Bacterial Disease of Oleander.* — C. 0. Smith finds that a disease 

 affecting the stem and leaves of Oleander, causing the formation of hard 

 woody knots, is due to a bacterium, the cultural and morphological 

 characters of which enable it to be identified with Bacillus Olece, an 

 organism producing a similar disease of the olive. f 



* Bot. Gazette, xlii. (1906) pp. 301-10 (4 figs.), 

 f See this Journal, 1887, p. 286 ; 1890, p. 498. 



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