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By the work of Anderson, who with 233 samples of milk sold in the City of Washington all from doubtful sources and showing but fifteen or 6.7 per cent. which contained tubercle bacilli pathogenic for guinea pigs. This milk came from 102 dairies only eleven of which were definitely proven by inoculation experiments to be peddling tubercle bacilli among their

customers.

By the work of Delepine in Manchester who out of 1,385 farms found a like percentage of milks which were virulent for experimental animals. Going back to these farms it was demonstrated that actual tuberculosis of the udder was the definite cause of infecting the milk in 78.8 per cent., that tuberculosis of the udder was the probable cause of 16 per cent., leaving nothing definite to connect the infectivity of the milk with udder disease in but 5.2 per cent.

By the work of Wollstein and Bartlett at the Babies' Hospital in New York, the autopsy record for six years of 1,320 autopsies showed 178 or 13.5 per cent. with tuberculous lesions. Of these, according to Park's estimations on similar cases from infants' hospitals, at least 10 per cent. were bovine and due to milk. This would be 1% per cent. of the entire number of autopsies. These were infants under three taken from the homes of families which could not afford anything but the cheapest grades of milk and were for the most part fed on impure milk. These 1,320 autopsies did not represent more than 25% of the sick children treated in the Babies' Hospital during this period. Consequently, of the whole number or four times as many, most of whom were drinking cow's milk as an exclusive diet before admission, about one-third of one per cent. were found to have bovine tuberculosis.

When we consider with these the mass of children in this same section of New York from which the patients were derived, which did not become ill enough to apply for hospital treatment, we find an infinitesimal proportion of children who drink poor cow's milk who develop bovine tuberculosis.

If this can be true of market milks from dairies, the animals in which are not always nor often properly tested with tuberculin, in which cows with active tuberculosis are not always excluded, then logically the danger from milk drawn from tuberculin tested herds and collected from animals which show no

physical evidence of disease of the respiratory or glandular systems, and with the practice of modern dairy methods, the probability of transfer of bovine tuberculosis through milk is, we believe, very small.

In order to measure the danger from bovine tuberculosis, we are almost entirely dependent upon inoculation experiments. The danger will never be determined by presumptuous statement nor by the ill-advised declarations of the alarmist but by scientific evidence patiently sought through reliable research laboratories.

The medical profession and the public are menaced by a bacillus far more vicious and virulent than the tubercle bacillus its name is Commercialism, its genus is greed for gold and its species is milk. It sometimes infects health officers, newspapers, self-constituted authorities on pure food and even infects well known milk crusaders. Commercialism is at the same time the most constructive and destructive agency in our midst because it has the inherent power of the almighty dollar.

If a philanthropy interferes with trade interests and the commercial interest determines to destroy confidence in the philanthropy, it needs only to subsidize a newspaper and hypnotize a crusader or two in order to accomplish its purpose. If it chances to be a pure milk philanthropy which is in the way, it proceeds to shield all lower grades of raw market milk and many other milk products used raw including butter and all kinds of ice cream and by a program of publicity with innuendo and distorted statement, it becomes the disturber of public confidence in the highest grade of milk.

The wonder is that the public and a part of the medical profession are so gullible and cannot interpret these trade practises nor recognize their true character.

President McCleave: This will conclude our scientific sessions for this year. We will meet upon the excursion tomorrow morning at 8:45, if you please.

There being no further business, on motion the Conference now adjourned, sine die.

Further Observations on the Germicidal Action of Milk* By Martin A. Beck, Department of Pathology and Bacteriology, University of Louisville, Ky.

This investigation on the germicidal action of milk was undertaken at the suggestion of Mr. Neill Roach.

It has been known for some time that milk kept at a low temperature and bacterial counts made on successive days presented up to a certain time a count which diminished from day to day. For this reason when the various dairies competed before Commissions which decided the quality of the various samples of milk, the requirement was made that the time when the milk was freshly obtained should be definitely stated.

At the time when this investigation was first considered we were not familiar with the work of others on the so-called bactericidal action of milk but we now feel, from a careful review of the literature, that this decrease in the number of bacteria has been clearly accounted for.

To review the literature would require considerable time. Briefly we may now mention the work of Fokker, Hesse, Heim, Schottelius, Klimmer, Conn, Heineman, Stocking, Behring, Knox and Schorer, Evans and Coke, and others. These authors do not uniformly believe that such a germicidal activity exists.

To give a brief resumé of the recent work which has been done we may cite the summary and conclusions of Rosenau and McCoy.

"Judged by the number of colonies that develop upon agar plates, the bacteria first diminished and then increase in number. This so-called germicidal property of milk occurs only in fresh raw milk. For the most part our work clearly shows that no actual reduction in the number of bacteria occurs. However, when compared with the controls, a restraining action is evident. The phenomenon in question therefore appears to resemble that of a weak antiseptic rather than that of a true germicide. When milk is kept warm (37 degrees C.) the decrease is pronounced within the first eight or ten hours. After this time the milk has entirely lost its restraining action. When the milk is kept cool

*The paper read by Dr. Beck at the Conference in Louisville, Ky., in 1912 was inadvertently omitted from the published proceedings of that meeting. In justice to him and to the advantage of our members, it is here presented.

(15 degrees C.) the decrease is less marked but more prolonged. The decrease in the number of bacteria is largely apparent, being due at least in part to agglutination. The bacterial clusters may, to a certain extent, be shaken asunder. This fact goes far to reconcile the discordant results of the various investigations upon the germicidal properties of milk. Those who used dilutions with vigorous shaking broke up the bacterial clusters and obtained a larger number of colonies upon agar plates than those who plated with different technique.

Some of the leucocytes in milk seem to possess the power of phagocytosis, judged by microscopic preparations. Phagocytosis, however, plays no essential part in the 'germicidal' action of milk, for the decrease is as marked in the cell-free milk as in the sediment rich in leucocytes.

The germicidal action of milk is specific. For instance, one sample restrained typhoid and staphylococcus pyogenes aureus but not paratyphoid a or b. Dilution experiments demonstrate the enfeeblement of agglutinins rather than the presence of a germicidal substance in solution.

The germicidal actions of blood and milk resemble each other in some particulars. Blood serum acts more quickly and much more powerfully than milk. Freezing milk for ten minutes and then thawing it does not affect the phenomenon in question. In one experiment freezing for 48 hours did not influence the restraining action upon typhoid, but destroyed it for B. lactis aerogenes. Boiling milk or heating it above 80 degrees C. destroys its germicidal properties. The effect of lesser degrees of heat varies with the micro-organism. Thus the restraining action for B. lactis aerogenes is weakened by first heating the milk at 55 degrees and almost destroyed at 60 degrees C.; for typhoid it is not affected by heating the milk at 60 degrees for twenty minutes, but is materially influenced at 70 degrees C. for thirty minutes.

The germicidal action of milk varies in different animals and in the milk from the same animal at different times. At most the action is variable and feeble. It cannot take the place of cleanliness and ice, but may be taken advantage of in good dairy methods."

A review of the literature would seem to show that the experiments to demonstrate the bactericidal action of milk were

done with bacteria not ordinarily present in Certified Milk but with certain bacteria under best conditions foreign to milk,— Cholera vibrio, staph. pyogenes aureus, B. thphosus, paratyphoid and various other organisms.

In our experiments the attempt was made to determine the action of the milk on those bacteria generally found in milk or on those bacteria which commonly contaminate milk. In all, ten samples from different dairies were studied, the samples being collected at different times, covering a period of four months. Through the kindness of Mr. Roach the samples were obtained as soon as possible after milking and delivered to the laboratory packed in ice. They were then transferred to sterile eight ounce bottles under aseptic conditions, this being done to prevent the contamination which was sure to result from handling so frequently the ordinary cardboard cover of the milk bottle. These were then packed in ice in a bucket and kept on ice in the refrigerator. The stopper and neck of the bottles were covered with paper while packed in ice and before removal of the stopper, the mouth of the bottle was carefully cleaned with sterile cotton. In the case of the samples from which counts were made each day for a month a duplicate sample was kept and only opened on the last day with the object of detecting any increase due to contamination. The counts showed little variation, eliminating any serious contamination. The medium used was standard agar, reaction one per cent. acid, and the dilution method was used in plating, one cc. of the dilution being added to each plate. Samples were vigorously shaken before plating. The incubation period was twenty-four hours at 37 degrees C. and forty-eight hours at 20 degrees C.

The results can be best indicated by citing the findings in one sample (No. 2) which will be considered typical although with other samples there were some variations. It will be seen from examination of the chart that milk plates incubated at 37 degrees C. show a progressive diminution up until the tenth day, the original count being 4,800, and the count on the ninth day 1,400 and on the tenth day 6,500. There was a gradual increase until the fourteenth day when the number reached 51,000. the twentieth day the count at 37 degrees C. was 260,000. Plates incubated at 20 degrees C. gave an original count of 1,700, on the fourth day the count was 1,300, fifth day 1,800, sixth day 3,500. It will be seen that the original count was reached much earlier on the plates incubated at 20 degrees C., this taking place

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