202 THE PRESERVATION OF MILK. 



as we have seen in 61, milk contains also sundry species of 

 bacteria capable of development at o C. Therefore if it be desired 

 to prevent the decompositions set up by these organisms, it will 

 be absolutely necessary to kill the germs. 



122. The Part Played by Milk as a Carrier of 

 Infectious Diseases. 



The aforesaid requirement is really imperative in view of the 

 fact that diseased cows which the owners often fail (or refuse) 

 to recognise as such yield milk containing pathogenic bacteria. 

 And this applies particularly to tuberculosis, from which complaint 

 (on a moderate computation) one cow out of every five in Germany 

 suffers. As reported by J. CH. BAY (I.), on the authority of a 

 compilation made by the Danish pathologist B. Bang (to whom 

 is due the honour of clearing up this question), out of 132,294 

 head of cattle examined in the Copenhagen slaughter-house be- 

 tween 1891 and 1893, no less than 23,305 (some 17.7 per cent.) 

 were recognised as tuberculous by macroscopic examination alone. 

 According to the researches of Dr. Martin, reported by R. CNOPF 

 (I.), one out of every thirteen samples of milk exposed for sale 

 in Paris contains tubercle bacilli, and from the results obtained 

 by Dr. Schroeder in Washington, at least one in every nineteen 

 samples of milk sold in that city contains a sufficient number of 

 tubercle bacilli to produce infection. For the microscopic in- 

 vestigation of the (specifically heavy) tubercle bacilli in milk, 

 the sample, previously prepared by skimming and clarifying, is 

 separated, by centrifugal force, in strong test-tubes, for which 

 purpose special processes have been designed by THORNER (I. ) and 

 ILKEWITSCH (I.). K. OBERMULLER (I.) examined Berlin market 

 milk in this way, and recognised it as infected with tubercle 

 bacilli in a high degree. In this connection it should be re- 

 marked that, according to determinations made in 1896 by A. 

 BULLING (I.), goats are also liable to this disease, and therefore 

 cannot be considered as immune. 



The extent of the danger attendant on the consumption of 

 unboiled milk is not sufficiently illustrated by the foregoing 

 particulars, which are only concerned with the possibility of 

 infection by such bacteria as are pathogenic for men and animals, 

 i.e. tuberculosis, anthrax, and so on. Milk is, however, also a 

 frequent carrier of typhus bacilli, which fission fungi (almost ex- 

 clusively pathogenic for the human subject alone) find their way 

 into the milk, either directly from diseased milkers or milk-dealers, 

 or from the milk vessels being swilled out with water containing 

 these microbes. Farmyard wells are frequently very close to 

 dunghills, cesspools, and closets, and if typhus breaks out on such 

 farms, then the well-water very soon becomes impregnated with 

 typhus bacilli by means of fcecal matter. Proofs of this exist by 



