Preparing enmlsions of B. salmonicida in 15 cc. of highly polluted 

 drain water, Williamson (1928) found that when it was unsterilized the 

 organisr^ could not be recovered, but when sterilized, B. salmonicida 

 persisted for 3 days, though in scanty numbers. 



Similarly, Home (1928) found that when 1 cc. of broth culture was 

 sewn into 100 cc. of crude sewage and sewage effluent and incubated at 

 room temperature, B. salmonicida was not recovered after 2 days. Sewage 

 was examined for the presence of B, sa]jnonicida by sowing a loopful onto 

 an agar plate. 



The results of Duff and associates (194-0) thus support the findings 

 of Plshn (1924) as to the ability of B. salmonicida to multiply in 

 sewags-polluted waters but are contraiy to those of Home (1928) and 

 Williamson (1928). Duff and associates (194-0) point out that the results 

 of the latter workers may have been influenced by the presence of 

 irhibltory trade wastes in sewage samples employed since the absence of 

 such agents is not explicitly recorded in their reports. The disagreement 

 may also be accounted for by differences in methods of sampling employed. 

 Duff and associates (194-0) found that at least in diluted autoclaved 

 sewage {see below) of widely varying organic content B. salmonicida count 

 raay di-op to a verj^ low figure (well below 100 per cc, ) within the first 

 iO days before extensive multiplication sets in. Duff and associates (194-C) 

 also point out that whereas Home (1928) and Williamson (1928) both 

 sampled by means of the loop, and they by -withdraTTLng 1 cc, of sample, 

 the employment of such small samples may have led to the lack of 

 veco-rery of the bacterium at a stage where it may have been present in 

 very small numbers. There are approximately 75 loopfuls in 1 cc, of 

 S* salT.onicida culture or in 1 cc, of average sewage dilution. 



The answer to the question of the viability of B. salmonicida in 

 polluted water in nature may reside in the nature of the polluting 

 material. There is no definite evidence of B. salmonicida being capable 

 ■:;f multiplying or surviving for ai-^' length of time in noxious trade 

 wastes. On the other hand, the extensive work of Duff and associates 

 (194-0) has shown that, providing sewage is free from trade and other 

 chemical wastes, B. saljionicida will survive under conditions of the 

 iaboratci-y for a considerable period (23 days). As far back as 1924, 

 Plehn stated that the danger of funjnculosis increases according to the 

 C!u.antity of pollution by organic matter, and she mentioned effluents 

 frciin dairies as being particularly harmful. 



U::di.livt3d^ Sewage Ste rilized by Berkefeld Filtration 



Duff and associates (1940) found that an initial inoculum of 100 

 ~ ^'^ ?.' i^ saljipnicii^a pe- cc. first greatly multiplied, then decreased, 

 the last colony appearing on the thirteenth day, when estimating the 

 .'lumber' of survivors by plate method. 



