104 MILK 



of chronic enteritis of cattle), the smegma bacilli found in smegma 

 and the mist bazillns isolated from manure. In general all these 

 bacilli morphologically resemble the tubercle bacillus but are for 

 the most part shorter and thicker and stain more uniformly. 

 They resist decolorisation by acids unless submitted to pro- 

 longed treatment while their resistance to decolorisation by 

 alcohol is somewhat inferior to that of the tubercle bacillus. 

 Injected into animals most of them, like the butter bacillus, 

 exert pathological effects with the production of nodules re- 

 sembling tubercles. The characteristic which essentially differ- 

 entiates them from the tubercle bacillus is their comparatively 

 rapid growth upon and in culture media. Their growth in 

 days exceeds that of the tubercle bacillus in the same number 

 of weeks. They will also grow at room temperatures. A further 

 point of differentiation is that they do not produce tuberculin. 



Examination for B. diphtheriae. This organism has been 

 found in milk, but only on a very few occasions. 



The method usually employed is to take advantage of the 

 rapid growth of this bacillus on blood-serum. 



The milk is centrifugalised in sterile tubes, and cultivations 

 are made from both the cream and the sediment. 



Dilution is obtained by acting upon the same principle as 

 that used in brushing agar and gelatine plates. A little sediment 

 or cream is taken up by a sterile platinum loop, and is rubbed in 

 close vertical lines over the surface of three blood-serum tubes 

 without recharging the loop. A large number of blood-serum 

 tubes should be inoculated from both sediment and cream, 

 incubated at 37 C., and examined after twenty to twenty-four 

 hours. All possible B. diphtheriae colonies must be carefully 

 examined (to diminish the work, surface sweepings may be 

 taken) in cover-slip preparation. If bacilli morphologically 

 resembling this organism are found, they must be subcultivated, 

 obtained in pure culture, and the virulence determined. 



Many observers have recorded the presence in milk of bacilli 

 which morphologically resemble the diphtheria bacillus, but 

 which from their other characters are certainly not that organism. 

 Their occurrence emphasizes the absolute necessity of carrying 



