206 



Journal of Applied Microscopy. 



out by the first milk drawn, but not all 

 removed until milking lias progressed 

 some time." 



Rotch^ concludes that the few cases in 

 which contaminated samples were 

 obtained from the strippings, were due 

 to faults in technique and not to bacteria 

 from the interior of the udder. 



Moore^ reviews the conclusions of 

 Schultz, Gernhart, and Rotch and gives 

 the results of his own investigation. In 

 every examination made he found the 

 last milk from at least one quarter of the 

 udder to contain bacteria. In concluding 

 his paper Moore suggests that a bacteri- 

 ologic examination of the larger milk 

 ducts and of the acini themselves might 

 throw some light upon the assumption of 

 Gernhart. Such an investigation was 

 rendered impossible at the time on 

 account of his inability to procure the 

 udder of a freshly killed milch cow. 



That sterile samples may frequently be 

 obtained directly from the teat is a fact 

 that has been demonstrated by many 

 investigators. But the frequency with 

 which these same workers have failed 

 leads to the conclusion that the last 

 milk contains only a few bacteria and 

 which may, or may not be contained in a 

 given small sample. Schultz, Gernhart, 

 Russell, Rotch, and Moore have all been 

 unable to get sterile milk in every case. 

 Information is not at hand concerning 

 the amount of milk taken for a sample, 

 except that Moore took 50 cc. of the last 

 milk. Conn*" suggests that the reason 

 the earlier workers obtained sterile milk 

 so readily was because they did not col- 

 lect large samples. He says: "Essen- 

 tially the same facts have been demon- 

 strated in regard to human milk. * « * 

 Honigmann", Knochenstiern'^ Ringel", 

 and Palleske" have all independently 

 found that it is impossible to get human 

 milk from the mammary gland in such a 

 way as to be sterile." 



Von Freudenreich" states that he 

 failed to obtain sterile milk in large 

 quantities although the udder was 



8. Dr. T. M. Rotch. Transactions of the 

 Association of American Physicians. 1891. 



9. v. A. Moore. Preliminary Investiga- 

 tions Concerning the Number and Nature of 

 Bacteria in Freshly Drawn Milk. Twelfth 

 and Thirteenth Annual Report of the 

 Bureau of Animal Industry, U. S. Dep't of 

 Agr., p. 261. 



10. W. H. Conn. Bull. No. 25, U. S. Depart- 

 ment of Agriculture, Office of Experiment 

 Stations, p. 9. 



11. Honigmann. Ztschr. Hyg. 14 (1893), p. 

 207. 



12. Knochenstiern. Inaug. Diss. Dorpat. 

 (1893). 



13. Rlngel. Munch. Med. Wochenschr. 

 (1893), p. 513. 



14. Palleske. Vlrch. Arch., 130 (1892), p. 185. 



15. Ed. von Freudenreich. Landwirt- 

 schaftliches Jahrbuch der .Srbweiz. (1891) 

 II, p. 18. 



washed and smeared with lard to pre- 

 vent contamination. In an attempt to 

 collect ten liters of sterile milk for an 

 experiment in cheese making, he was 

 unable to reduce the number below 212 

 bacteria per cubic centimeter. He calls 

 attention to the ease with which a few 

 cubic centimeters are collected, using the 

 same precautions, but he does not recog- 

 nize the presence of bacteria from with- 

 in the udder. 



Those who believe the last milk to be 

 absolutely sterile when drawn from the 

 teat must necessarily explain the con- 

 stant presence of bacteria in the fore- 

 milk. The explanation is substantially 

 as follows: Bacteria in the air or in 

 stable filth accidentally gain a foothold 

 in the milk remaining on the end of the 

 teat after milking. The favorable condi- 

 tions for bacterial growth offered by the 

 ducts favor the multiplication of the in- 

 vading bacteria, which increase so rapid- 

 ly as to account for the presence of the 

 multitudes always found in the fore milk. 

 Experiments by the writer have shown 

 that It is possible for this to occur under 

 certain conditions, but the more probable 

 explanation is embodied in the results of 

 the investigations about to be described. 

 These will be treated under three separ- 

 ate heads, as they have in common only 

 the fact that they lead to the same con- 

 clusion. 



THE PERSISTENCE OF CERTAIN SPECIES OF 

 BACTERIA IN THE FORE MILK. 



The Work of BoUey and Hall is the 

 only investigation on the subject that 

 has come to notice. Samples of 

 milk were taken by means of a sterile 

 milking tube inserted through the duct 

 into the milk cistern. Some species were 

 found common to both the first and the 

 last milk drawn. Only one organism 

 was found common to the milk of all the 

 animals examined, that one having no 

 effect upon the milk. The writers con- 

 clude that a given form, once present, 

 may be quite constant in its occupancy 

 of the udder in an individual. 



In the investigations which I have 

 made to determine the nature of the milk 

 duct flora, the following methods were 

 adopted. Before collecting samples, the 

 udder and flanks of the cow were thor- 

 oughly moistened to prevent the dislodg- 

 ment of dust by the movements of milk- 

 ing. In addition, the teats were moist- 

 ened with a solution of mercuric chloride. 

 Samples were drawn directly from the 

 teat into sterile test-tubes, which were 

 provided with cotton plugs. In this 

 respect the work of the writer differs 

 from that of Bolley and Hall. Cultures 

 were made immediately after collecting 

 the samples. Five two hundred and fif- 

 tieths (5-250) of a cubic centimeter of 



