THE PRESENCE IN MILK OF CERTAIN ORGANISMS 259 



milk which had been used. All the milk was obtained from tuber- 

 culin-tested cows kept at the experiment station and was of super- 

 lative quality. 



At the time of the experiment it was not known that one cow 

 in the herd from which the milk was obtrined was infected with the 

 Bacillus Abortus, and it appears that there was at that time on. 

 evidence whatever of the cow being thus infected. Working in 

 conjunction with Cotton, Schroeder had previously discovered 

 that milk containing this bacillus, if injected into guinea-pigs, 

 gave rise to this disease in guinea-pigs. 



In another paper Schroeder (2) showed that many if not most 

 cows that become infected with the Bacillus Abortus remain chronic 

 carriers for long periods of time, possibly permanent carriers, and 

 that the bacillus is of common occurrence in the milk of rows that 

 have ceased to abort and have produced several healthy calves in 

 succession. Among aborting cows the bacillus appears in the 

 milk before an abortion occurs, and in one instance was discovered 

 in the milk of a cow that did not abort until 255 days later. These 

 facts afford strong testimony to the impossibility of securing milk, 

 from even the most carefully supervised cows, that can be guaranteed 

 free from the germs of disease. 



Although somewhat beyond the immediate scope of this work, 

 it may be mentioned that Teacher and Burton found that abortion 

 in guinea pigs was apparently produced both by streptococci and 

 by a diphtheroid bacillus. In two cases the changes in the placenta 

 resembled the white infarctions found in human placentae : no 

 bacteria could be found, but the authors believed that the lesion 

 was probably of streptococcal origin. 



D. On Milk-borne Epidemics. It is not proposed to enter 

 into any detail as to the epidemics which have been attributed to 

 milk-borne organisms. For the most part these epidemics have 

 been of the nature of sore throats varying greatly in intensity. Some 

 diphtheria epidemics have also occurred. Three outbreaks, which 

 will not be dealt with, are stated to have been of the nature of 

 gastro-enteritis. In some cases the symptoms have been of an 

 extremely severe type, and although the sore throat was the primary 

 symptom, this has been succeeded by serious secondary troubles, 

 leading in many cases to death. 



In 1912 Savage summarised the epidemics which have been 

 regarded as being due to milk in this country. 



Out of nineteen epidemics investigated, the source of infection, 

 although most certainly due to milk, could not be precisely traced, 

 but the remainder of the epidemics were traceable in most cases 

 quite definitely to a diseased cow. 



Of the last the following is a brief summary : 



Rugby 1880 Apparently due to a cow suffering from mastitis. 



Dover 1884 Believed to be due to cows among whom some had 



suffered from foot-and-mouth disease. 



s 2 



