BACTERIA IN MILK. 77 



there are comparatively few of these latter, find their best devel- 

 opment in the absence of air, in fact there are some even that abso- 

 lutely refuse to grow at all when even a trace of air is present. 



Milk as drawn from the naturally healthy cow is practically 

 free from bacteria, yet unfortunately it is not destined to remain 

 so. The sources of the bacteria in the normal milk are more 

 numerous than one would naturally suppose at first. The so- 

 called fore-milk seems always to contain the germs of souring, 

 and should be rejected if it is desired to obtain a milk as nearly 

 free from bacteria as is possible. However, more serious and 

 greater sources of bacteria arise from the introduction of hay- 

 dust, hairs and manure into the milk. With regard to 

 this latter it is commonly thought that excreta can be removed 

 from milk by straining it through cloth, but as a matter of fact 

 this is not the case, for about one-half of cow-dung dissolves di- 

 rectly in the milk, and at the same time millions of fecal bacteria 

 find their way into it, and growing there, produce very unpleas- 

 ant odors and tastes. 



As I have previously said, it has long been known that milk 

 as it is secreted in the cow's udder is practically if not entirely 

 sterile. Some ten years ago Prof. Sedgwick and Mr. Batchelder 

 succeeding in drawing milk free from bacteria by the use of ster- 

 ilized milking tubes. Last spring I tried a similar experiment 

 in a somewhat different manner. I had an apron made so as to 

 cover the entire sides and flanks of the cow, only allowing the 

 teats to protrude. By this means all hair, dust, etc.. were pre- 

 vented from falling into the milk when it was drawn. The hands 

 and teats were carefully washed with corrosive sublimate solu- 

 tion and then about a dozen test tubes that had previously been 

 sterilized were successively filled from the same teat. Portions of 

 these samples were at once used for making gelatine plate cul- 

 tures and then the remaining milk was placed in an incubator at 

 9S°F. These tubes were examined daily and any change in the 

 milk noted. 



Tube I — Containing the fore milk coagulated at the end of 

 two days, and the corresponding plate culture showed it to con- 

 tain 1 160 bacteria per cubic centimeter.* 



Tube II — Remained sweet four days and showed 180 bacte- 

 ria per c. c. 



Tube III — Sample taken after a pint had been drawn, re- 

 mained sweet six days and showed 20 bacteria per c. c. 



Tube IV, Etc. — Several successive tubes taken by sterilized 

 milking tube, remained good for seven days, but showed no col- 

 onies on plates. (Probably a few bacteria got into the milk, but 



♦About a quarter of a teaspoonful. 



