208 



Journal of Applied Microscopy. 



but three species of bacteria were found. 

 On the first day that the millt was 

 examined, streptococcus was found to 

 predominate in numbers in all four of the 

 teats. The other two species occurred 

 only occasionally, but in the later exami- 

 nations they were found to exceed the 

 streptococcus in number. 



The presence of streptococci in milk 

 from a normal udder is, in the experience 

 of the writer, unusual. None have been 

 found in the milk of eight cows in the 

 same stable, or for that matter, in any 

 examination of fore milk from cows else- 

 where. The persistence of the strepto- 

 coccus in the milk of the one cow is 

 therefore of special significance. 



The mathematical probability that the 

 same organism will invade the same 

 sterile milk duct, even twice in succes- 

 sion, is infinitely slight. It is therefore 

 necessary to seek other explanation for 

 the constant presence of bacteria in the 

 fore milk, when we consider the persist- 

 ence of species in the milk of certain cows 

 or in particular quarters of the udder of 

 the same cow. 



AN EXPERIMENT IN COLONIZING THE 

 CISTERN WITH BACTERIA. 



With reference to determining the pos- 

 sibility for an organism to persist in the 

 cistern for a considerable period it was 

 determined to introduce, into one quar- 

 ter of the udder, a culture of an easily 

 distinguished bacillus. For this purpose 

 Bacillus prodigiosus was selected because 

 the red color of its growth on agar would 

 render its presence in milk easily recog- 

 nized when cultures were made. Four 

 cubic centimeters of a bouillon culture 

 were introduced into the cistern by 

 means of a hyperdermic syringe length- 

 ened with a milking tube. Both the milk- 

 ing tube and the syringe were scalded to 

 guard against introducing any other 

 micro-organisms along with prodigiosus. 

 It was known from work already done 

 that the organism in question was not a 

 natural inhabitant of the udder with 

 which the experiment was being made. 



The use of the milking tube, as is 

 nearly always the case, occasioned an in- 

 flammation of one side of the udder. The 

 inflammation is attributed to the use of 

 the milking tube rather than to Bacillus 

 prodigiosus. The threatened obstruction 

 of the teat by the accumulation of irreg- 

 ularly shaped masses of casein, rendered 

 it necessary to frequently draw out the 

 purulent liquid from the diseased quar- 

 ter of the udder during the two following 

 days after which the inflammatory con- 

 dition subsided. Plate cultures were 

 made each day. On the day following the 

 inoculation, ten colonies of Bacillus pro- 

 digiosus appeared on the plates. 

 Although the same amount of milk was 



used in making the cultures on the days 

 following, the number of colonies was 

 observed to decrease in number. On the 

 sixth day, the colonies of that bacillus, 

 ceased to appear. During the whole 

 period, with the exception of the first 

 two days, colonies of the native bacterial 

 flora were observed in each plate culture. 

 The fact that an organism selected at 

 random, without considering its fitness 

 for inhabiting the udder, should succeed 

 in persisting there for six days is signifi- 

 cant. The experiment demonstrates the 

 fact that frequent and thorough milking 

 may not remove all bacteria from the 

 udder. That other species of bacteria, 

 better fitted for that environment, are 

 able to persist in the udder for longer 

 periods seems highly probable. 



A BACTERIOLOGIC EXAMINATION OF THE 

 GLANDULAR TISSUE OF THE UDDER. 



The writer is indebted to Dr. Moore 

 for the suggestion of this line of work 

 and for the privilege of associating with 

 him in an investigation based upon it. A 

 partial report of the results obtained has 

 been published elsewhere^". In attempt- 

 ing to draw conclusions from the facts 

 which have already been presented, the 

 writer finds himself unavoidably influ- 

 enced by the facts brought to light in 

 the work to which reference has been 

 made. That his conclusions may not ap- 

 pear to be based upon a less firm foun- 

 dation of fact than is the case, he feels 

 justified in here referring to the joint 

 labor. 



The fundamental method underlying 

 the investigation consisted in making a 

 large number of cultures directly from 

 freshly exposed glandular tissue. Sterile 

 tubes, tubes containing about 15 cc. each 

 of gelatin, and some containing slanted 

 agar were taken to the place of slaughter. 



The purpose was to compare the bac- 

 teria found in the fore milk with those 

 which might be found in the udder. 

 Samples of the fore milk and in one case 

 of the strippings, were taken immediately 

 before the slaughter. In order to obtain 

 more definite results, each quarter of the 

 udder was arbitrarily divided into three 

 divisions. The first (A) included the teat 

 and milk cistern. The second and third di- 

 visions (B,C) included horizontal zones of 

 equal thickness constituting the remain- 

 ing portion of the udder. (See illustra- 

 tion). 



Each cow was milked before killing. 

 Immediately after slaughtering the cow, 

 the udder was carefully removed. The 

 skin was reflected and a flamed knife 

 was used to make a dorso-ventral incision 

 several inches in depth in one quarter of 



16. V. A. Moore and A. R. Ward. BuH. 

 No. 158, Cornell University Agricultural 

 Experiment Station. January, 1899. 



