THE PRESENCE IN MILK OF CERTAIN ORGANISMS 249 



Hamburger found that the organisms were arranged in the 

 form of diplococci with a sort of halo, which did not however stain 

 with any of the capsular stains. The diplococci were placed end to end, 

 and when grown on milk these organisms showed chain formation. 



Further work on similar lines has been carried out by Rolling, 

 Puppel, Stowell and Hilliard, and others. 1 



There seems little doubt that streptococci are present in the 

 milk of cows which cannot be regarded as other than healthy. 

 Moreover, these organisms occur when the milk is collected with 

 the strictest aseptic precautions, as is the case with ' certified ' * 

 milk, as given below. 



Heinemann obtained ' certified ' milk and allowed it to stand 

 for eight days to become sour. He then investigated the milk 

 for streptococci and found these organisms present in all dilutions 

 used, both at room temperature and at 37 C. He then took 10 

 litres of this milk and divided it equally into forty-two flasks. Of 

 the forty-two flasks thirty-eight were heated in a steam steriliser 

 for three successive days. All except one of the flasks which had 

 been heated were then inoculated with streptococci obtained from 

 numerous sources, namely, human faeces, cow faeces, milk, separator 

 slime, sewage, etc. He found that all these strains when grown 

 in milk tended to develop the characteristic diplococci and their 

 chain formation. 



Rosenow obtained milk with a milking-tube from twelve 

 apparently healthy cows. Five of the samples were sterile. Of 

 the other seven, three showed large numbers of streptococci after 

 incubation, and of these two varieties were found to be virulent on 

 injection. He found that streptococci, when grown in milk, take on 

 the characteristics of those found in epidemic sore-throats. The 

 greatest effect is produced when the organisms are grown in unheated 

 milk, less being produced when grown in pasteurised milk, and 

 little or none when the milk has been heated in the autoclave. He 

 also investigated a large number of streptococci obtained from 

 milk and from epidemic sore-throats. Slime was obtained from 

 the milk of known farms, and was subjected to a process of 

 cleansing in a special clarifying machine. He also used the sediment 

 obtained from a cream separator. Immense numbers of strepto- 

 cocci and other bacteria, also of leucocytes and foreign matter, 

 were found in the material obtained from both sources. Emulsions 

 of the organisms which were made and injected into animals were 

 found to be highly pathogenic, the animals dying within three days. 

 Virulent cultures of streptococci were obtained from the exudate 

 or from the blood in thirteen out of fifteen animals examined. 

 A pseudodiphtheria bacillus was the next commonest organism found 

 in the investigation. 



1 Cp. also work by Rosenow and Moon, and by Krumwiede and Valen- 

 tine, published since the above was written. 



* For explanation of the term ' certified,' see p. 271. 



