of extended studies have not supported this idea. Christison and 

 associates (1938) found that in twenty rivers in which phage was detected, 

 there was no known furu.nculosis and in five instances no phage was 

 detected where the disease had occurred. This phage was present and 

 furunculosis had occurred^ however, in fourteen cases. It has been 

 shown to be absent from water in which an epizootic was in progress 

 (Furunculosis Committee 1935). The lytic principle has been demonstrated 

 in winter when the infection was in abeyance as well as in summer when 

 the disease was prevalent^ it has also been found in city sewage though 

 absent from city water supply (Christison et al. 1938). The most 

 recent work on this phage shows that it is impossible to correlate its 

 presence or absence with the presence or absence of the disease or with 

 the distribution of the infection. An explanation for the occurrence 

 of this phage where no disease was known, may reside in the resistance 

 of the phage. This may explain its widespread dispersion by water birds. 



In the Tissues of SaMon and Trout 



Technique in isolation and demonstration 



Christison and associates (1938) removed the gut and other organs 

 (liver, heart, kidneys, and spleen) mincing them up separately in sterile 

 dishes (the gut in one, the other organs in another) o The two lots of 

 viscera were then placed in separate flasks, each containing 300 to 

 400 cc. of broth. To each flask was then added a mixture of broth 

 emulsions of 24. hours' agar cultures of twelve strains of B. salmonicida 

 used in the isolation of phage from river waters. The resulting 

 mixtures were incubated at room temperature for 24 hours. The cultures 

 were then filtered separately through filter paper impregnated with 

 kieselguhr to remove gross particles and then through Chamberland L5 

 filters. After being tested for sterility, the filtrates were stored 

 in sealed ampoules or test tubes in an ice chest until required for use. 



Each filtrate was tested against each of twelve strains of B. 

 salmonicida, in the usual manner, to determine the presence of 

 bacteriophage . 



Occurrence 



In human diseases such as cholera and cfysentery, very active 

 phages for the causal organisms have been obtained from the dejecta of 

 infected persons, particularly in the convalescent stage of the disease. 

 It was thought that this might occur in furunculosis, and Christison 

 and associates (1938) examined a number of fish with this in mind. 



In a number of cases active phages were isolated. It is of 

 interest to note that the organs of some fish which had not died of 

 furunciilosis yielded phage, while the organs of fish which had died of 

 the disease did not always contain phage, as far as could be ascertained 

 by the technique used. Phage plaques were found in the primary cultures 



28 



