PURE MILK

AND THK

PUBLIC HEALTH

A MANTAL, OF

Milk and Dairy Inspection

BY ARCHIBALD ROBINSON WARD, B. S. A., D. V. M

Assistant Professor of Bacteriology and Director of the State Hygienic laboratory,
University of California, Berkeley, California.

WITH TWO CHAPTKRS

BY MYER EDWARD JAFFA, M.S.

Professor of Nutrition and Director of the State Food and Drnn I,aboraton
University of California.

WITH SEVENTEEN ILLUSTRATIONS

ITHACA, N. V

TAYLOR & CAKPKNTKK

1909

COPYRIGHT 1909
BY TAYLOR ^ CARPKXTKR

TO

VERANUS ALVA MOORE

WHOSE INSPIRING WORK AS A TEACHER
AND INVESTIGATOR IN THE FIELD OF COM-
PARATIVE PATHOLOGY AND BACTERIOLOGY
IS EXERTING A PROFOUND INFLUENCE IN
UPLIFTING THE VETERINARY PROFESSION,
THIS BOOK IS DEDICATED.

190867

PREFACE.

The relation of milk to the public health and the means
employed to ensure a safe milk supply is a subject of varied
aspects. The proper control of the public milk supply requires
more or less of the services of the bacteriologist, the chemist,
the physician, the veterinarian, and the progressive dairyman.
The ordinary fund of technical knowledge possessed by any one
of these classes is not sufficient for coping with the difficulties
encountered in carrying on efficient and comprehensive meas-
ures for milk and' dairy inspection. Furthermore, knowledge
concerning the subject is being rapidly increased by contribu-
tions widely scattered in technical journals.

The writer has attempted the difficult task of assembling the
essential facts for the information of the health officer and
others directly concerned in the crusade for better milk. The
class of individuals particularly addressed is such, that a gen-
eral knowledge of bacteriology is assumed to be possessed by
the reader.

Each chapter is accompanied by a list of references bearing
on the subjects discussed. Throughout the text, numbers in
parenthesis, referring to the authorities given at the -end of the
chapter, have been freely used. These references serve in some
cases to give statements greater weight than a mere unsup-
ported personal opinion would have, and in all cases permit
those particularly interested to gain access readily to the details
concerning the points at issue.

In the preparation of the book, the writer has become greatly
obligated to his colleague, Professor M. E. Jaffa, for writing
chapters X and XI. With reference to those chapters, Pro-
fessor Jaffa desires to have it stated that he has not attempted
to present the details of the more common methods employed
in the chemical examination of milk. This branch of milk
inspection is the most advanced and the methods are well estab-
lished. He has been content to indicate what should be done

VI PREFACE.

and to refer to standard works on the subject for the methods
except in the case of some of the simple tests.

Dr. William H. Boynton, Assistant in Pathology and Bac-
teriology, New York State Veterinary College, has very gener-
ously permitted the use of the photographs appearing as figures
13 and 14, together with his description of them, in advance
of publication by himself. Professor G. C. Watson, General
Manager of the Tully Farms, Tully, N. Y., has kindly per-
mitted the use of photographs appearing as figures 3 and 4.
Dr. Francis H. Slack, Chairman of the Committee of the
American Public Health Association on Standard Methods of
Bacterial Milk Analysis, has rendered assistance by furnishing
a manuscript copy of the 1908 report of that Committee.
Specific acknowledgement as to sources of information has
been made largely throughout the text by means of the system
of references employed.

It is not safe to indulge in the hope that important work
has not been overlooked, or that new facts may not require a
modification of attitude towards certain troublesome problems.
Therefore, assistance tending to improve the book will be
gratefully received.

A. R. W.

TABLE OF CONTENTS.

LIST OF FIOURKS ix TKXT xiu

CHAPTER I.

THK CONTAMINATION OF MII^K.

Character of bacteria
Significance
Foremilk
Coat of animal

Hxterior of udder 6

^Shape of milk pail 7

«/fhe milker

Milking machines

V Stable -, 10

Floor 10

Mangers and stanchions
Barn improvements
Feeding

vBpecial milking rooms

^Cleansing of utensils. 13

Scalding .. 13

Construction of utensils 15

^Handling milk.

Bottling milk.... I6

Milk room .... 16

/Delivery of milk.. 16

Milk flavors

Sediments 17

References

CHAPTER II.

CHANGES IN MII.K CAUSED BY BACTERIA.

Significance of bacterial contamination ...

Numbers of bacteria in market milk ....
Kffect of temperature on bacterial growth..
vMethods'of cooling
vMilk during transportation.
Preservation bv chemicals ..... 26

VIII CONTEXTS.

Lactic acid fermentation 26

Putrefactive processes 29

Organisms causing putrefaction .... 29

Antagonism of lactic acid fermentation 29

Conditions controlling putrefaction 29

Source of putrefactive organisms 30

Toxic milk ... 30

Ropy milk ... 30

Cause of ropy milk 31

Biological characteristics of //. I act is I'isrostts.... 32

Sources of contamination of milk 32

Means of combating ropy milk ...... 33

Germicidal activity 34

References ... . 38

CHAPTKR III.

EPIDEMIC DISKASKS TRANSMITTED BY MIIyK.

Transmission of diseases of man bv milk 41

Character of milk-borne epidemics 41

Typhoid fever 42

Investigations in the District of Columbia.. 42

Importance of milk as a carrier 43

Sources of the contamination of milk 45

Detection of milk-borne typhoid fever epidemics 46

Berkeley, Cal., outbreak 49

Diphtheria . 51

Recognition of milk-borne diphtheria epidemics 52

Milk-borne diphtheria in Oroville, Cal. 53

Scarlet fever 54

Gastro-intestiiial infections 55

References . 56

CHAPTKR IV.

BOYINK TrBERCn.OSIS AND OTHER CATTLE DISEASES.

Bovine tuberculosis 59

Losses to the live stock industry 59

Transmission by milk 59

Infection of swine 60

Insidious onset 60

Conditions governing prevalence 60

Prevalence in herds 61

Contamination of milk by tubercle bacilli .. 62

Tubercle bacilli in market milk bt

Human and bovine tvpes of tubercle bacilli ... 63

• CONTENTS. IX

Views of Koch 64

Bovine tubercle bacilli in man.. . 64

Intermediate types of tubercle bacilli 65

Channels of infection 65

International Congress of 1908 66

Tuberculosis in Japan 66

Present status of controversy 67

Protection of the milk supply 67

Measures against bovine tuberculosis 67

Physical examination
Tuberculin test
New tests for tuberculosis
Stable sanitation and tuberculosis 72

Tuberculin test ordinances ... 72

Clean herds the goal .
The Washington plan
Test by city official

Test by any licensed veterinarian 76

Milk contracts 76

Application of the tuberculin test 77

Temporary numbers

Facilitating observations of temperatures 77

Injection with tuberculin 79

Temperatures after injection
Interpretation of temperatures

Limitations of tuberculin test 79

Fraud

Permanent identification of animals
Disposal of tubercular animals
Disinfection

Education of dairymen concerning bovine tuberculosis

Anthrax l%

Suppuration

Cowpox

Parturition disturbances ....

Malta fever 87

Foot and mouth disease

Milk-sickness

References

CHAPTER V.

MUNICIPAL, SANITARY CONTROL OF MII.K.

Control of milk supply
•^Inspection

The dairv score card .

X CONTENTS.

Improvement in Richmond. Ya. 103

Washington milk supply 104

Educational activities 104

Inspection of cows 105

Inspection of dairy apparatus 105

Inspection of water supply 106

Scope of inspection 106

The score card for city milk plants 106

Milk-borne epidemics 109

Temperature standard 109

Numerical determinations of bacteria in milk 110

Education of the public 112

References 112

CHAPTER VI.

PASTEURIZATION OK MILK.

General definition 114

Incentives for pasteurization 114

^Conditions required for killing bacteria 115

Bacterium tuberculosis 115

Alteration of milk by heat 115

Cooked taste 115

Alterations of milk constituents 115

Creaming quality 116

Vital qualities of milk 116

Spore-bearing bacteria. 116

Bactericidal efficiency 117

Low-temperature pasteurization. 117

High-temperature pasteurization 118

Commercial pasteurization . 118

Efficiency 119

Continuous-flow machines popular 120

Care subsequent to heating 121

*» Pasteurization in Chicago 121

Pasteurized milk in infant feeding 122

^-Pasteurization of municipal milk supplies 123

References . 124

CHAPTER VII.

MICROSCOPIC TESTS OK MII,K.

Mammitis in the cow 126

Tests for cellular content of milk 126

Stokes' test 126

Stewart's test ... .. 127

CONTENTS. XI

Slack's test

Doane- Buckley test

Savage's test ..: 131

Troniinsdorff's test 131

Significance of results 132

Streptococci in milk

Microccocci in milk

Leucocytes in milk 134

Summary 136

Bloody milk
References

CHAPTER VIII.

IJACTKRIO^OGICAI, KXAMINATION OF MII,K.

Numerical determination of bacteria

Significance of results

Microscopic estimate of bacteria

Tests for ]>. toll

Kxaminations for typhoid fever and diphtheria bacilli

Tubercle bacilli '

Determination of streptococci

Qualitative determinations

References ...

CHAPTER IX.

CKRTIFIKD MII.K

Milk commissions ....

Association of milk commissions

Source of authority

Field of milk commission activities
Agreement with dairymen

Sanitary requirements for dairymen
Experts employed by milk commissions

Veterinary inspection

Bacteriological examinations 165

Chemical examinations. 166

Medical inspection..
V-The certified milk package

Amount of certified milk produced. 168

Fraudulent certified milk
I Maintenance of standard
Milk dispensaries

Rochester, N. Y., milk dispensaries

References 172

XII CONTENTS.

CHAPTKR X.

TH1-; ANALYSIS OK MII.K.

Introduction 174

Composition of milk 174

Protein 174

Fat 174

Carbohydrates 1 76

Mineral matter 176

Solids of milk 176

Effect of feeding on the composition of milk 176

Sampling milk 177

Specific gravity 177

Determination of fat in milk and cream 179

Interpretation of specific gravity and fat 180

Solids not fat ISO

Preliminary tests of milk 182

Acidity of milk 182

Federal standards 183

State standards 1S4

Collection of samples 1<S4

References 185

CHAPTKR XI.

AIH-I/TKRATION OK MILK.

Introduction 187

Tests for preservatives 190

Borax 190

Formaldehyde 190

Hehner's test for formaldehyde 191

Leach's test for formaldehyde 191

Watering of milk 191

Skimming 192

Carbonate of soda 192

Thickening agents for cream 193

Heated milk 193

Coloring matter 193

References 194

FIGURES IX TEXT.

Fig. 1. Section of one quarter of the udder of a co\v 1

Fig. 2. Pearson's milk pail 7

Fig. 3. A convenient stable 10

[LXrUSTRATIONS.

XIII

Fig.
Fig.
Fig.
Fig.
Fig.
Fig.
Fig.
Fig.

Fig. 12.

Fig. 13.
Fig. 14.

Fig. 15.
Fig. 16.

Fig. 17.

Sterili/.er containing racks for holding bottles 14
Ropy cream lifted with a fork 31
liacillns lactis VtSfQSUS 31
Germicidal action of freshly drawn milk 35
L,aundrv in which milk cans were washed 50
Conditions surrounding- a case of typhoid fever 51
Blank for recording temperatures 78
Ear-tag for marking cattle SO
Card employed by the writer for the identification of cows 81
Moak's card for identifying cows 83
Diagram showing 'improvement in dairy scores in Rich-
mond, Va. 104
Section of udder showing epithelial cells .. 134
vSection of udder showing epithelial cells and polynuclear

leucocytes - 135
Chart showing relation of municipal milk stations to infant

mortality 171

Appendix A.
Appendix B.
Appendix C.
Appendix D.
Appendix E.

APPENDICEvS.

Dairy ordinance of Berkeley, Cal.

Chicago tuberculin test ordinance

Duluth milk ordinance

Blank for reporting existence of infectious diseases..

Poster for dairy barns

195
200
206
211
212

Index

214

CHAPTER I.

THE CONTAMINATION OF MILK.

Uddef. Milk conies in contact with bacteria in the lactif-
erous ducts of the udder at the moment of secretion. The
normal healthy udder of the cow harbors bacteria throughout
its whole extent. Fig. 1
shows the extent of the
lactiferous ducts of the
udder and the direct com-
munication with the ori-
fice of the teat.

There was current at
one time a belief that the
interior of the udder is
sterile, except, perhaps,
the teats, and that failure
to obtain sterile samples
of milk was due to con-
tamination from bacteria
in the teats, or from ex-
ternal sources. Moore
(41) suggested the
method of attacking the
problem by the bacterio-
logical examination of
the normal udders of re-
cently slaughtered cows.
The results obtained by
this method of investi-
gation (42, 44, 66, 67)
diametrically opposed Fig- 1- Section of one quarter of the

current belief and have udder of a cow at a plane intersectinS
Iave the teat and milk cistern. Photograph

led numerous workers to by the author, from a museum specimen
repeat the experiment prepared by Dr. G. S. Hopkins.

2 THE CONTAMINATION OF MILK.

(5, 25, 27, 28, 47). The conclusions drawn from this line of
work have been in substantial agreement upon the point that
milk is contaminated before it reaches the teats. The subject
is further treated in references 4, 9, 26, 31, 32, 68.

The number of bacteria found in the udder is less than
would be expected elsewhere under similar conditions of food,
moisture and temperature away from vital influences. The
germicidal influence of fresh milk has been cited as an explan-
ation of the fact (25, 28). The last of the milk drawn at
any one milking contains less bacteria than that first drawn,
but is seldom found to be sterile, if any but minute quantities
are taken for examination. In fact, the " strappings " have
been found to contain more bacteria per cc. than that drawn
immediately before stripping. If a cow is not stripped, — that
is, if a little milk is left in the udder, — the next milking will
show a number of bacteria larger than usual. This fact has
been explained by assuming that thorough milking removes
the bacteria from the milk ducts more completely than the
ordinary milking (60). It is evident that the few bacteria
remaining in the ducts after milking constitute the source of
the relatively larger numbers in the milk obtained during the
fore and middle portions of the succeeding milking. It is not
believed that the udder is subject to indiscriminate invasion by
a variety of forms, but rather that the conditions found there
are such as limit the bacterial flora. A number of attempts to
colonize the udder \vith a variety of organisms have not met
with success. Bacillus prodigiosus , an organism easily recog-
nized in cultures by the red color, has been used several times
with the result that inflammatory conditions have been set up.
The observed persistence of this organism for twenty-two days,
while the udder was inflamed, does not prove .much, in view
of the disease, and it was obtained in constantly decreasing
numbers, which led to the conclusion that multiplication had
not occurred (53). In one instance the teat of a goat was
injected with B. prodigiosus and after slaughter, three days
later, cultures showed that the organisms had invaded the
udder (25). The fact that this particular organism is not
an udder organism, and was used on account of its chromo-

UDDER. 3

genie power, should be noted. Experiments with forms
undoubtedly habituated to conditions within the udder have
been made in very few instances and further work along this
line is desirable. The observed persistence of certain bacteria
in certain particular quarters of the cow's udder from day to
day is of significance (26, 66). The presence of bacteria in
the udder is paralleled by the case of other mucous membranes.
These facts render it unnecessary to look to hematogenous
infection as the immediate source of the bacteria in the milk,
even though bacteria have been demonstrated in other normal
organs like : the spleen (21). Such an explanation of the
source of the bacteria would hardly account for the difference
of the bacterial flora of different quarters of the udder. No
evidence has been brought forward to substantiate the notion
that the bacterial content of milk is influenced by bacteria in
feed or water transferred via intestines, blood, and udder.
Conclusions contradicting this view have been drawn from
observations which have shown that the common bacterial flora
of the udder is quite different from that of the intestines (26).
Experiments have been made by feeding certain micro-organ-
isms to cows and then searching for the same organisms in the
milk, without success. The results might have been otherwise
if care had not been taken to prevent contamination from the
feees. One writer used B '. prodigiosus (66), while another (26)
used the same organism in one trial, and at another time used
distillers' grains containing yeasts, oidium, proteuS, bacilli.,
and streptococci. The bacterial content of milk drawn under
aseptic precautions has been determined in .cows fed on hay
and on grass, and no difference was found in the numbers
present in the milk (26) . The' bacteria in feed and water may
modify the bacterial co'ntent of the milk, but by other channels
than through the interior of the udder.

Character of bacteria. The Organisms most frequently found
are micrococci, in general capable of producing visible changes
in milk rather tardily (67), and hence they do not interfere with
its apparent keeping quality. Conn, Esten and Stocking (ll)
have pointed out that one of these udder organisms {Micro-
coccus lactis varians} is the most common and widely distributed

4 THE CONTAMINATION OF MILK.

organism in milk, and have observed that it is identical with,
or closely allied to, Micrococcus pyogenes aureus {staphylococcus
pyogenes aiireus} . Willem and Minne likewise regard these
organisms, found in freshly drawn milk, as M. pyogenes (68).
Streptococci, indistinguishable from Streptococcus pyogenes,
have been isolated from milk taken from the normal udder
under aseptic precautions (47). They have been observed in
the milk of a cow in the Cornell University dairy herd for a
period of two years and a half, during which time there was
no occurrenc^ <)f udder trouble. This streptococcus when
injected int6 a healthy udder produced mammitis. The ex-
cellent record of milk production for several years previous
gave assurance that the animal had not suffered a severe attack
of streptococcus infection of the udder (47). A number of
species have been described as occurring in freshly drawn milk,
but the variety of species is very much restricted as compared
with those encountered in market milk.

Significance. The presence of bacteria within the udder con-
stitutes an obstacle to the production of absolutely sterile milk.
v. Freudenreich collected samples, with aseptic precautions, at
the beginning, the middle and the end of the milking, deter-
mining the number of bacteria present. The average results of
185 determinations gave for the beginning, 6505 per cc.; for
the middle, 1341 percc.; and for the end, 769 percc. Kuntze
(Ref. .22, Chap. II) obtained an average of 419 per cc. from
40 samples of freshly drawn milk taken at different times dur-
ing a year. Some very careful American work has shown that
the contamination of the whole milking, mostly from within
the udder, may vary from 200 per cc. to 900 per cc., depending
upon the cow, the average being about 500 per cc. The
methods' of aseptic production of milk have reached such a
point of refinement in some dairies that the bacteria unavoid-
ably introduced from the udder constitute the bulk of the
bacteria present in the product when bottled. The occurrence
of micrococci and streptococci in milk in the udder is a circum-
stance that certainly cannot justly be attributed to carelessness
in milk production. Nevertheless, in some cases the contam-
ination from this source has been lessened by avoiding the use

COAT OF ANIMAL. 5

of cows with leaky teats. Dr. R. G. Freeman has found that
such show a higher bacterial count in the freshly drawn milk
(67). The possibility of improvement in this direction is
apparently limited, for v. Behring reports that out of a herd
of 30 cows, hardly 10% approach the condition of the theoret-
ically perfect cow, i.e., one having no bacteria in the udder (6).

Foremilk. The very first stream of milk from the teat has
been found to contain from 1,000 to 50,000 bacteria per cc.
(26). The average of 70 experiments by Conn (10) gives
6,900 per cc. The recognition of the fact that the first streams
of milk drawn contain more bacteria than that drawn later
suggested the practice of rejecting the first stream or so, to
lower the general bacterial content of the milking. A separate
vessel is sometimes provided, to avoid the necessity of drawing
this foremilk upon the floor of the stall. The whole of the
milk contains more or less bacteria and the contamination from
the first milk drawn has little effect upon the general average.
It has been shown that the rejection of three streams from each
teat reduces the bacterial content of the whole milking by 4
per cent. , an amount practically negligible (60) . The rejection
of the foremilk is practiced much more generally than is neces-
sary, for there are few dairies indeed where the contamination
from the foremilk is a noticeable factor as compared with that
from other sources. This detail is a survival of the time when
it was universally believed that the contamination in milk as
drawn was derived from the orifice of the teat.

Coat of animal. The excrement and mud adhering to the
hair of the cow constitute a most abundant source of contam-
ination. The amount of filth carried by the animal is greatly
influenced by the condition of the barn-yard, varying with the
season. Accumulations of manure to which the cows have
access, aggravate conditions. Poor location of barns with re-
spect to drainage sometimes creates conditions that cannot even
be alleviated by the use of gravel and stone. Instances of the
paving of the barn-yard with stone and with cement are known.
Currying and brushing the cows is effective, and should be
completed at least half an hour before milking is begun. Such
a period of time permits the bacteria-laden dust to settle to the

6 THE CONTAMINATION OF MILK.

floor, if the stable be free from draughts. Brushing just before
milking will usually double the number of bacteria that would
otherwise have gained entrance during milking (60). In the
best dairies the switch of the tail is washed before the milking.
Precautions are taken to prevent switching, by the use of a tail
holder (Ref. 8, Chap. IX).

Exterior of udder. The udder and teats are especially ex-
posed to filth, either from the barn-yard or the stable floor when
the cow is lying down. The movements of the udder, during
milking, tend to constantly dislodge dust and hair which fall
into the milk pail. Dairy practice should include the washing
of the udder and teats before milking, when filth is present,
and the dampening of the hair whether dirt is present or not.
If the udder is left dripping wet, the dirty water will become
a source of contamination of the milk. The dampening causes
the dust to adhere to the hair and largely eliminates an im-
portant contaminating influence. If the hair of the udder is
kept clipped short, the cleaning is greatly 'facilitated. The
value of dampening the udder may be demonstrated by a simple
bacteriological experiment. Sterile Petri dishes, containing a
suitable solid culture medium, may be exposed under the
udder for half a minute during milking before and after damp-
ening. After the lapse of time sufficient to permit bacterial
growth, the number of colonies of bacteria showing on the
two plates will exhibit a wide difference in the number present
in favor of dampening (51). The number of bacteria shaken
from apparently clean udders may be reduced by two-thirds,
by merely dampening. The possibilities of contamination,
from really dirty udders, are enormous. By dampening the
udder and flanks the contamination may be reduced to about
ten percent, of that which would otherwise have occurred (60).

In the certified dairies maintaining the greatest aseptic pre-
cautions, the methods of cleansing the udder are very carefully
considered. Practice varies, but the following method will
suffice to illustrate the point : Wipe udder and adjoining parts
with burlap to remove particles of bedding, wash with luke-
warm water applied with a cloth, spray with lukewarm water,
wipe W7ith a freshly laundered bath towel. This is so folded

SHAPE OF MILK PAIL.

that one towel may be used on four cows, a fresh surface being
used on each udder.

After cows have been cleaned before milking it is desirable
to prevent their lying down and becoming soiled. A cow
kneels on the fore legs before lying down, and a light chain
passed under the throat and affixed to the stanchion will pre-
vent her doing so.

Shape of milk pail. Bacteriological examinations of the
foregoing nature have suggested modifications in the shape of
the milk pail to minimize the contamination. The changes
have been along the line of reducing the area of the opening
down to the minimum size that maybe used without seriously
inconveniencing the milker. Fig. 2 shows a desirable type
of milk pail. When the pail
is in use, the hood is kept up-
permost, and since a pail is
held at an angle to the floor,
between the milker's knees,
the hood prevents the vertical
exposure of the opening. Cov-
ered pails with an aperture,
containing a cheesecloth or a
wire gauze strainer, are infer-
ior to the pail with the small
open area protected by a hood.
Such a pail offers a greater
area open to contamination,
and the strainer does not con-
stitute a barrier to the entrance
of bacteria. Nevertheless the
covered pail with cheesecloth
strainer is very convenient for
the milker and is a great im-
provement over the common • Fig. 2. Pearson's milk pail
open pail. Such a pail will (Orig.}.

exclude 29 per cent, of the total bacteria and 41 per cent, of
lactic acid organisms as compared with the ordinary open pail
in a cleanly dairy. In an extremely dirty dairy the same pail

8 THE CONTAMINATION OF MILK.

(with strainer) will exclude as high as 97% of the bacteria
that fall into the common open pail (59). A strainer of
absorbent cotton apparently enmeshes some bacteria and keeps
them from the milk. Tests of the Gurler pail have shown
that the use of cotton reduces the bacterial count to 30% of
that obtained when the pail is used without the strainer (61).

The milker. The milker is the most important factor in
the production of clean milk. Success or failure depends
upon his training and faithfulness in carrying out details, the
significance of which he may not appreciate nor respect.
Milkers, with the exception of a very few in model dairies,
trained by bacteriologists, exhibit a low degree of cleanliness
in their work. The results obtained by different men, working
under the same rules for asepsis, are striking. A group of
five students in the Connecticut Agricultural College, trained
in the theory of dairy bacteriology, were able to draw milk
with one-third the bacterial content of that drawn by the two
regular milkers. A well trained college graduate, in charge
of the dairy herd, was able to obtain results seven times as
good as those obtained by the same two milkers (60). The
practice of wetting the hands with milk, which afterwards
drips from the teat into the pail, is far from uncommon. It is
usually not the practice even to wash the hands before milking.
The practice of providing clean overalls for the milkers should
be more general. In some certified dairies the milker wears a
freshly sterilized suit at each milking period, washes his hands
after milking each cow, and uses a sterilized milking stool.
The milker as a factor in the contamination of milk with the
germs of the infectious diseases of man, will receive consider-
ation in Chap. III.

Milking machines. The advent of the milking machine has
been welcomed by some, with the idea that its use would
practically eliminate the sources of bacterial contamination
within the stable. Hopes in this direction have not been
entirely realized. The machine necessitates bringing milk into
contact with rubber tubes, which have long been recognized
as objectionable. Rubber is very difficult to cleanse thoroughly,
in a bacteriological sense, and it is certain that the care given

MILKING MACHINES. 9

by the average dairyman will not satisfy requirements. The
complexity of the apparatus and the work involved in taking
the machine apart twice a day for cleaning and scalding, afford
an excuse for doing it but once a day, a practice which cannot
be too strongly condemned. Harrison has compared hand
milking with one of the earlier types of milking machine with
the result that the machine drawn milk was found to contain
from three to twenty times the number of bacteria found in
hand drawn milk (28). Stocking (62) has shown the infer-,
iority of machine drawn milk with the ordinary care given
machines. He paid particular attention to methods of cleaning
the rubber tubes, and by the exercise of elaborate precautions,
was able to produce results favorable to the machine. The
experiments show the possibility that the milking machine, in
the hands of an exceptionally careful dairyman, may decrease
the pollution of milk. Erf (20) made similar experiments
with the care of the rubber parts and in comparative tests of
the keeping quality was able to show results in favor of the
machine. Tests of milking machines usually have been con-
cerned chiefly with methods of caring for the rubber tubes used
with the machines. It has been found necessary to keep the
tubes in an antiseptic solution when not in use. Among the
substances that are permissible are brine, 3% formalin solution
or lime water prepared with an excess of fresh unslacked lime
(30). After use the tubes are rinsed in cold water, then with
hot water, and then immersed in the solution. If air remains
in any portion of the tubes, bacteria will multiply at that point.
Before use on the cow, the tubes must be thoroughly rinsed
with hot water to remove the antiseptic. If formalin is used
as an antiseptic there is always the possibility that it will not
be rinsed out thoroughly, — either through carelessness or inten-
tion. On this account the use of this common milk preserv-
ative should be interdicted. The use of the milking machine
ought to lessen the danger from the contamination of milk by
the germs of infectious diseases of man, for it eliminates one
of the stages in milk handling during which persons come in
close contact with the milk. Nevertheless, there are many
other sources for possible infection of milk from diseased per-

10 THE CONTAMINATION OF MILK.

sons. The milking machine increases rather than lessens the
possibility of ordinary contamination, -and, so long as rubber is
used in its construction, it cannot be regarded as a simple
means for avoiding contamination.

Stable. The construction of the building and its condi-
tion as regards cleanliness are important factors in milk pro-
duction. The desirable sanitary features in a stable are those
contributing to easy cleaning, freedom from dust, good venti-
lation and abundant lighting. A one-story structure obviates
the undesirable features of the ordinary dusty ceiling with hay

Fig. J, A convenient stable.

loft above, and, further, usually contributes to better ventila-
tion. Conditions permitting draughts of air, which stir up
dust, are to be avoided: Fig. 3 shows a convenient stable.
Note the suspended railway track, by means of which the
manure is removed in 'buckets to a wagon. The railway is
used in a similar way to bring in feed.

Floor. Cement is vastly preferable to wood as a floor, for it
cannot become saturated with filth to give rise to offensive
odors. By accurate construction of the gutter behind the
cows, drainage conditions may be made perfect. A rough
sandpaper finish obviates the danger of cows slipping. Planer
shavings (17), as bedding, offer the minimum of possibility

STABLE . 11

of bacterial contamination, but the use of this material must
of necessity be restricted to a very few of the best dairies.

Mangers and stanchions. Wooden mangers, when old, be-
come harboring places for decomposing feed, especially if in-
dividual compartments are provided for each cow. Ease of
cleaning has resulted in the general use of one continuous
cement trough for the whole row of cows. Separate cement
mangers, if the cows are habituated to taking certain places,
would have a slight tendency to restrain the spread of bovine
tuberculosis. In the best stables, wooden stanchions' have
been supplanted by a variety of iron devices. The stanchions
should be spaced from three to three and one-half feet from
center to center, at the least, in order to give room between
cows. The swing stanchion is preferable, because it restricts
movement forward and backward and thus contributes to the
cleanliness of the cow (65).

Barn improvements. The general use of the model dairy
barn in milk production cannot be brought about immediately.
Therefore at present we have the problem of adapting the older
inferior structures to the requirements of clean milk produc-'
tion. Fortunately, with slight structural changes and the 'ex-
ercise of -care, milk of a very satisfactory sanitary quality may'
be produced in such barns. The condition of the ordinary
wooden floor may be greatly improved by the use of land plas-
ter or sawdust as an absorbent of liquids. Changes for im-
proving the lighting and ventilation are usually possible. ' Ven-
tilation, most important in cold climates where cattle are' shel-
tered in the stable, becomes a negligible factor in mild climates
where the cattle are kept indoors only during milking. The
accumulation of manure near the building may be avoided
by keeping a wagon convenient for loading directly from the
stable. At certain seasons the manure may be carted directly
to the fields, and, at other times, to a satisfactory distance from
the barn. Whitewashing is one of thejnost popular

for improving interior conditions. Its occasional application
with a brush removes, for the time being, much dust arid cob-
webs, besides improving the lighting. It is fairly efficient for
disinfecting purposes, some other agents being more active.

12 THE CONTAMINATION OF MILK.

Feeding. The dust in the air occasioned by the feeding of
grain and hay, during the milking, increases the bacterial con-
tent of the milk drawn during the feeding by about one-third
of that of cows milked when not feeding, other conditions be-
ing alike. The feeding of dry corn stover, immediately before
milking, also increases the contamination to about threefold
of that occurring without such source of dust in the air (60).

Feeding hay during the milking period is a common practice
by no means necessary. Cows accustomed to at least eating
grain at that time require considerable training before they
will patiently wait until after milking for their feed. Delay
in feeding in some cases undoubtedly adds some extra trouble
to the attendants, but is practiced in the best dairies.

Certain feeds are highly objectionable because of their effect
upon the cow. Brewers' grains, distillers' grains, and sugar-
beet pulp are a cheap source of feed in certain localities, and
they are fed in great quantity long after attaining an advanced
stage of fermentation. The result is a chronic diarrhea in
the cows and conditions in the stable that prevent the drawing
of clean milk. It is not at all unlikely that milk from cows
almost exclusively fed on such highly fermented food, would
contain substances not found in the milk of cows consuming
wholesome feed. On the other hand, the use of limited quan-
tities of beet pulp and the like, when fresh and combined with
a properly balanced ration, seems to cause no trouble. These
products, when dried, are unobjectionable (37).

Special milking rooms. Efforts to reduce bacterial contam-
ination to the minimum have, in some dairies, led to the con-
struction of a milking room apart from the general stable where
better aseptic conditions might be maintained. Such construc-
tion as to permit sterilization of the walls, floor and ceiling,
together with the absence of the contaminating features of
feeding and manure, offered hope of reducing bacterial contam-
ination. Such rooms are necessarily small and a few cows at
a time are admitted. Results have been disappointing, for the
movements of the cattle dislodge the dust from the hair and
result in a higher bacterial content of the air than in the general
stable where the cattle stand quietly. An open shed in a pas-

CLEANSING OF UTENSILS. 13

ture offers the best conditions for milking, as regards the con-
tamination from air.

Cleansing: of utensils. The proper care of the vessels with
which milk comes in contact is an important factor in reducing
contamination. No precaution for producing good milk is
more easily carried out, yet none is more generally neglected.
Rinsing in cold or lukewarm water is necessary first to remove
the milk. If hot water is used at first it will render cleaning
difficult by causing some of the milk constituents to adhere to
the utensils. This preliminary step is followed by scrubbing
with hot water containing soap powder or some alkali (16, 58),
and this in turn by rinsing in hot water. The practice of
merely rinsing utensils without washing and scalding, after
the night's milking, and then using them the next morning, is
intolerable.

Scalding. Too often, the final rinsing in hot water is con-
sidered sufficient. Bacteriological requirements, however,
demand the more thorough application of heat. Harrison (28)
and Russell (50) have shown the inefficiency of the ordinary
haphazard scalding. To insure complete destruction of all bac-
teria,— that is, sterilization, — requires that the utensils be sub-
jected to steam under pressure of at least five pounds for twenty
minutes. Fig. 4 shows the apparatus used for this purpose,
containing a car used for milk bottles. This method of heating
utensils is the only one that may properly be designated as ster-
ilization. The others do not sterilize, as they do not result in
the death of all the spores of bacteria. Very excellent results
may be obtained by subjecting the utensils to the action of steam
in a closed chamber, but not under pressure. La Grange (38)
tested the effectiveness of such a piece of apparatus, finding that
99.2% of all bacteria in milk bottles were killed . Those surviv-
ing were spore-bearing organisms. To obtain this result the
steam was admitted to the room for fifty-five minutes, about
.half of this period having elapsed before the temperature reached
the boiling point. It is the more common practice to scald
utensils over a jet of steam, one by one. La Grange used steam
from a half -inch pipe, under a pressure of thirty pounds, and
with a duration of fifteen seconds obtained results as satisfac-

14 THE CONTAMINATION OF MILK.

tory as by the other method tested by him. When the oper-
ator is in a hurry, and shortens the exposure down to three
seconds, the efficiency of the method is open to question. The
machine in which bottles, in an inverted position, are passed

fig. 4. Sterilizer containing racks for Jwlding bottles.

over steam jets, likewise does poor work, unless its speed is so
slackened as to reduce its rated output (54). Boiler scale com-
pounds, or oil in the feed water, may so taint the steam that
an objectionable odor will be transmitted to the cans or bottles
and thence to the milk or cream.

HANDLING MILK. 15

Boiling water must of necessity be used by the smaller pro-
ducers. If it is provided in sufficient amount and used with a
recognition of the fact that time of exposure, as well as temper-
ature, is a factor in killing bacteria, excellent results may be
obtained. A large caldron should be provided in which such
articles as strainers and coolers could be -immersed for several
minutes. Cans should be filled with boiling water and allowed
to stand for some minutes before being emptied. After scald-
ing and draining, utensils should be kept in a place protected
from contamination by dirt.

The cooler permanently installed, and too large to place in a
sterilizer, is scalded properly with great difficulty. The use of
streaming steam, applied with a hose, is a tedious process, which
invites carelessness on the part of the man doing the work.

Construction of utensils. Cracks or seams of utensils and
rust spots afford points for the lodgment of milk, which 'accu-
mulates in spite of washing, and contributes to contamination.
Seamless pails are preferable, but if joints are present they
should be flushed with solder. Metallic strainers are the worst
offenders in this respect. Valves are a necessary evil, as con-
stant vigilance is necessary to keep them clean. Pipe offers
exceptional difficulties in the way of cleaning and scalding,
while rubber hose is even worse. The use of wood anywhere
that milk will come in contact with it, is very undesirable, on
account of the impossibility of cleansing it properly. Wooden
plugs for milk cans are still used in New England in spite of
their unsanitary qualities.

Handling1 milk. Immediately after drawing, milk is strained
and passed over a piece of apparatus for the purpose of cooling
and aerating. Uncleanliness of the apparatus or its location
in dusty air, offer opportunities for contamination. Straining
through cotton cloth does not remove bacteria (12, 14); on
the contrary, it may add them if the apparatus is not sterile.
Absorbent cotton, between layers of cheesecloth, is the most
satisfactory medium for removing visible filth from milk.
Clean cheesecloth alone is preferable to the wire strainer in
its usual dirty condition. Milk coolers practically all work
on the principle of bringing milk in contact with surfaces

16 THE CONTAMINATION OF MILK.

cooled by water. There may be a water leak in the apparatus,
causing contamination from that source. Milk cans are fre-
quently stood in tanks of water, for cooling, and splashing
may cause water to reach the milk. The practice of adulter-
ating milk with water is common enough to deserve note as a
source of contamination. Bergey (8) has given figures show-
ing the increase in the bacteria of milk at different stages in
handling, derived from various utensils.

Bottling milk. The filling of milk bottles in the larger dairies
is done rapidly by the use of a bottling machine. In some
cases a machine is used which also places the paper caps in
position. This is desirable, from a hygienic point of view,
because it eliminates the dangers associated with the handling
of the paper caps when this is done by a man. When the
machine is used, the caps are sterilized before using. When
bottles are capped by hand danger from contamination by the
workman may be minimized by the use of a special copper
tube with a slit on two sides. The caps are stacked in this
tube when sterilized, after which they are removed and used
by touching the edges only (Ref. 8, Chap. IX).

Milk room. The cooling and subsequent manipulation of
the milk should be carried on under conditions as free as pos-
sible from the influence of dusty air. A room or building sep-
arate from the stable should be provided for the purpose. A
cement floor, screened windows and ease of cleaning are desir-
able features of such a structure. In the best dairies admit-
tance to the milk room is denied to the milker and even visit-
ors. Elaborate precautions are taken to prevent contamination
of the milk during straining, etc., even the air being freed
from bacteria before entering the room through the ventilating
system.

Delivery of milk. Bacteriological considerations lead to the
conclusion that delivery in sterile bottles, filled at the dairy,
offers the least possibility of contamination in transit. But
the milk bottles must be cleaned and heated well before use,
if for no other reason than the fact that milk bottles are put to
disgusting uses in some households. Bottled milk is not always
what it should be, as for instance when the driver fills a dirty

SEDIMENTS. 17

bottle on the wagon to satisfy a customer's demand for ' ' bottled
milk." Dipping or pouring from delivery cans multiplies the
possibilities for the entrance of bacteria.

Paper bottles used but once would avoid some of the dan-
gers attributable to the use of glass bottles (57). They have
been before the public for some time, but apparently their dis-
advantages outweigh the advantages, for they have hot come
into general use.

Milk flavors. Care must be exercised in the production
of milk to avoid certain undesirable flavors in the product.
Garlic, onion, turnip, when fed before milking, will taint the
milk. Experiments have shown that the feeding of anise,
fennel and garlic, taints the milk through the excretion of the
flavoring substances by the udder ( 19) . Similar considerations
point to the necessity of care in the administration of drugs to
milch cowrs, for fear of transmitting the drug to the milk.
Backhaus (3) regards the influence of food on the flavor and
wholesomeness of milk, through this channel, as unimportant.
Warm milk absorbs odors from stable air more quickly than
cold milk. It has been shown that exposure from one-half hour
to an hour and a half at 57°-72°F. to the odor of either corn
silage, horse manure, oils of cinnamon, wintergreen or pepper-
mint, will impart the characteristic odor to milk (52). Fresh
urine also imparts an odor, absorbed from the air. Particles
of manure by dissolving in the milk impart a flavor. The
flavors from silage and alfalfa are not at all offensive, and milk
consumers become accustomed to them. The process of aerat-
ing milk remedies such defects (39). Aeration is not necessary
when milk is drawn under the very best conditions.

Sediments. The deposit in milk, consisting of mud, feces,
hair, etc., all too common in milk as delivered to the cus-
tomer, bears witness to the carelessness in milking (35, 36).
Straining removes much of the coarse material, but it is fre-
quently found necessary to resort to a more effective process.
The milk is run through a cream separator for the purpose of
removing the foreign matter by the action of centrifugal force.
It is effective, so far as dirt, etc., is concerned, but not in the
case of the bacteria, which largely remain in the milk (43).

18 THE CONTAMINATION OF MILK.

Iii fact, passing milk through a centrifugal machine increases
the apparent number of bacteria by separating the clumps (55,
56).

REFERENCES.

1. ANDERSON. The cow and her stable. Bui. No. 204, Agr. Exp.
Sta. Univ. of CaL, Berkeley, Cal., 1908.

2. BACKHAUS und APPEI,. Ueber aseptische Milchgewinnung. II,
Ber. Landw. Inst. Univ. Konigsb, V, 1898-1899, S. 73.

3. BACKHAUS. Einfluss des Putters und der Individualitat der Milch-
kuh auf Geschmack und Bekommlichkeit der Milch. Ber. Landw. Inst.
Univ. Konigsb., V, 1898-1899, S. 110.

4. BACKHAUS und APPEIV. Ueber aseptische Milchgewinnung. Ber,
Landw. Inst. Univ. Konigsb., 1903.

5. EARTHED. Recherches sur les microorganismes de 1'air des etables,
du lait au moment de la traite et de la mamelle. Rev. Gen. Lait, lre
Ann£e, 1902, No. 23, p. 529.

6. BEHRING. Suppression of tuberculosis in cattle and the hygienic
production of milk. Paper read at the XXXIV Plenary Meeting of the
German Agricultural Council.

7. BELCHER. Clean milk. New York : The Hardy Publishing Co.,
1903.

8. BERGEY. Sanitary supervision of the collection and marketing of
milk. Univ. of Penn. Med. Bui., July- August, 1904.

9. BURR. The source of acid organisms of milk and cream. Centbl.
Bakt., etc., 2 Abt., Bd. VIII, 1902, No. 8, S. 236.

10. CONN. Bacteria in freshly drawn milk. Fifteenth Ann. Rept.
Storrs Agr. Exp. Sta., Storrs, Conn., 1903, p. 92.

11. CONN, ESTEN and STOCKING. Classification of dairy bacteria.
Eighteenth Ann. Rept. Storrs Agr. Exp. Sta., Storrs, Conn., 1906,
p. 91.

12. CONN and STOCKING. Comparison of bacteria in strained and
unstrained samples of milk. Fifteenth Ann. Rept. Storrs Agr. Exp.
Sta., Storrs, Conn., 1903, p. 33.

13. CONN and STOCKING. Aseptic milk. Fifteenth Ann. Rept. Storrs
Agr. Exp. Sta., Storrs, Conn., 1903, p. 52.

14. CONN and STOCKING. Strained and unstrained milk preserved
at 70° and 50°. Fifteenth Ann. Rept. Storrs Agr. Exp. Sta., Storrs,
Conn., 1903, p. 38.

REFERENCES. 19

15. DAIRY DIVISION, BUREAU OF ANIMAL INDUSTRY. Suggestions
for construction of a modern dairy barn. Cir. No. 90, Bur. Anim. Ind.,
U. S. Dept. Agr., Washington, D. C., 1906.

16. DOANE. The disinfectant properties of washing powders. Bui.
No. 79, Maryland Agr. Exp. Sta., College Park, Md., 1902.

17. DOANE. Tests of materials for bedding cows. Bui. No. 104,
Maryland Agr. Exp. Sta., College Park, Md., 1905.

18. D'Hiui,. Zeitschr. Fleisch u. Milchhyg., 1905, S. 84; also, Jour,
of Compar. Path, and Ther., Vol XIX, 1906, p. 50.

19. DROMBROWSKI. Some experiments on the passage of odorifer-
ous and coloring substances into milk. Arch. Hyg., Vol. Iv, 1904, No.
2, p. 183. Abstract in Exp. Sta. Rec., Vol. XVI, No. 1, p. 191.

20. ERF. Milking machines. Bui. No. HO, Kansas State Agr. Col.
Exp. Sta., Manhattan, Kan., 1906.

21. FORD. The bacteriology .of healthy organs. Trans. Assoc.
Amer. Phys., Vol. XV, 1900, p. 389.

22. FRASER. Preventing contamination of milk. Bui. No. 91, Univ.
of III. Agr. Exp. Sta., Urbana, 111., 1903.

23. FRASER. City milk supply. ' Bui. No. 92, Univ. of III. Agr.
Exp. Sta., Urbana, 111., 1903.

24. FRASER. Effect of corn silage on the flavor of milk. Bui. No.
101, Univ. of III. Agr. Exp. Sta., Urbana, 111., p. 644.

25. FREUDENREICH. Ueber das Vorkommen von Bakterien im Kuh-
euter. Centbl. Bakt., etc., 2 Abt., Bd. X., 1903, No. 13, S. 401.

26. FREUDENREICH. Ueber die Bakterien im Kuheuter und ihre Ver-
teilung in den verschiedenen Partien des Melkens. Landw. Jahrb.
Schweiz., 1904.

27. FREUDENREICH und' THONI. Uber die in der normalen Milch vor-
kommenden Bakterien und ihre Beziehungen zu dem Kasereifungs-
prozesse. Landw. Jahrb. Schweiz., 1903.

28. HARRISON. The bacterial contamination of milk and its control.
Trans. Canad. Inst., Vol. VII., 1902-1903, p. 467.

29. HARRISON and GUMMING. The bacterial flora of freshly drawn
milk. Jour. Appl. Micro, and Lab. Methods, Vol. V, No. 11, p. 2029.

30. HASTINGS and HOFFMANN. Bacterial content of machine-drawn
and hand-drawn milk. Twenty-fourth Ann. Rept. Agr. Exp. Sta. Univ.
Wis., Madison, Wis., p. 213.

31. HENDERSON. A contribution to the study of mastitis in cows.
Jour, of Comp. Path, and Ther., Vol. XVII, 1904, p. 24.

32. HENDERSON. The relationship of the bacteriological condition
of the udder to the health of the community. Jour. Sanitary Institute,
Vol. 25, 1904, p. 563.

20 THE CONTAMINATION OF MILK.

33. HOPPER. Suggestions for the improvement of dairy barns. Cir.
No. 95, Agr. E.rp. Sta. Univ. III., Urbana, 111., 1905.

34. HUNZIKER. The care and handling of milk. Bui. No. 203, Cor-
nell Univ. Agr. Exp. Sta., Ithaca, N. Y., 1902.

35. KOBER. Milk in relation to public health. Senate Document
No. 441, 57th Congress, 1st Session, Washington, D. C., 1902.

36. KOBER. Milk sediments or dirty milk in relation to disease.
Cir. 114, Bur. Anim. Ind., U. S. Dept. Agr., Washington, D C., p. 18.

37. L/INDSEY. Distillery and brewery by-products. Bui. Aro. 94,
Hatch Exp. Sta. Mass. Agr. Col., Amherst, Mass., 1904.

38. IvA GRANGE. A comparison of methods of scalding milk cans by
steam. Thesis for the degree of Bachelor of Science, Univ. Cal., Berke-
ley, Cal., 1906.

39. MARSHALL. The aeration of milk. Contributions to Medical
Research, dedicated to Victor C. Vaughan, p. 237. Ann Arbor, Mich.:
George Wahr, 1903.

40. MARSHALL. The discussion of the milk problem from the stand-
point of production. Bui. No. 228, Mich. State Agr. Col. Exp. Sta.,
Agricultural College, Mich., 1905.

41. MOORE. Preliminary investigations concerning the number and
nature of bacteria in freshly drawn milk. Tivelfth and Thirteenth Ann.
Kept. Bur. Anim. Ind., U. S. Dept. Agr., Washington, D. C., p. 261.

42. MOORE. The normal bacterial invasion of the cow's udder. Pro-
ceedings of the Society for the Promotion of Agricultural Science, 1899.

43. MOORE. Inefficiency of milk separators in removing bacteria.
Yearbook, U. S. Dept. Agr., Washington, D. C., 1895, p. 431.

44. MOORE and WARD. An inquiry concerning the source of gas
and taint producing bacteria in cheese curd. Bui. No. 158, Cornell.
Univ. Agr. Exp. Sta., Ithaca, N. Y., 1899.

45. PEARSON, R. A. Facts about milk. Farmers' Bui. No. 42, U.
S. Dept. Agr., Washington, D, C., 1906.

46. PEARSON, R. A. Care of milk on the farm. Farmers'1 Bui. No.
63, U. S. Dept. Agr., Washington, D. C., 1897.

47. REED and WARD. The significance of the presence of streptococci
in market milk. Amer. Med., Vol V, 1903, No. 7, p. 256.

48. REYNOLDS. Milk as affected by stable practices and subsequent
handling. Proc. Amer. Vet. Med. Assoc., 1907, p. 338.

49. ROBY. The economic production and distribution of clean milk.
Jour. Amer. Med. Assoc., Vol. 46, 1906, p. 1430.

50. RUSSELL. Outlines of dairy bacteriology. Madison, Wisconsin :
H. L/. Russell.

REFERENCES. 21

51. RussEU*. The sources of bacterial infection and the relation of
the same to the keeping quality of milk. Eleventh Ann. Rept. Agr.
Exp. Sta. Univ. of Wis., Madison, Wis., 1894, p. 150.

52. RUSSEW*. Relative absorption of odors in warm and cold milk.
Twentieth Ann. Rept. Agr. Exp. Sta. Univ. of Wis., Madison, Wis.,
1903, p. 236.

53. RusSEUv and HASTINGS. Disappearance of bacteria artificially
introduced into cows' udders. Twenty-first Ann. Rept. Agr. Exp. Sta.
Univ. of Wis., Madison, Wis., 1904, p. 164.

54. RUSSEXI, and HOFFMANN. Bacteriological test of a bottle-wash-
ing device. Twenty-second Ann. Rept. Agr. Exp. Sta. Univ. of Wis.,
Madison, Wis., 1905, p. 227.

55. SEVERIN. Vermindert die Zentrifugierung die Bakterienzahl in
der Milch? Centbl. Bakt., etc., 2 Abt., Bd. XIV, 1905, S. 605.

56. SEVERIN and BUDINOFF. Contribution to the bacteriology of
milk. Centbl. Bakt., etc., 2 Abt., Bd. 14, 1905, S. 463.

57. STEWART. The single service milk bottle; its advantages and
adaptability for general use. Sanitation, December, 1904.

58. STEWART. Cleansing of milk vessels : relative value of washing
powders. Amer. Med., Vol. XI, 1906, No. 7, p. 241.

59. STOCKING. Efficiency of a covered pail in excluding filth and
bacteria from milk. Foiirteenth Ann. Rept. Storrs Agr. Exp. Sta.,
Storrs, Conn., 1901, p. 105.

60. STOCKING. Quality of milk as affected by common dairy prac-
tices. Eighteenth Ann. Rept. Storrs Agr. Exp. Sta., Storrs, Conn.,
1906, p. 66.

61. STOCKING. Comparative studies with covered milk pails. Bui.
No. 48, Storrs Agr. Exp. Sta., Storrs, Conn., 1907.

62. STOCKING. Bacteriological studies of a milking machine. Bui.
No. 92, Bur. Anim. Ind., U. S. Dept. Agr., Washington, D. C., 1907.

63. STOCKING and MASON. Milking machines. Effect upon quality
of milk. Bui. No. 47, Storrs Agr. Exp. Sta., Storrs, Conn., May, 1907.

64. SWITHINBANK and NEWMAN. The bacteriology of milk. L/on-
don : J. Murray, 1903.

65. TRUEMAN. Improving dairy conditions. Bui. No. 53, Storrs
Agr. Exp. Sta., Storrs, Conn., 1908.

66. WARD. The persistence of bacteria in the milk ducts of the cow's
udder. Jour. Appl. Micros, and Lab. Methods, Vol. I, No. 12, 1898,
p. 205.

67. WARD. The invasion of the udder by bacteria. Bui. No. 178,
Cornell Univ. Agr. Exp. Sta., Ithaca, N. Y., 1900.

22 THE CONTAMINATION OF MILK.

68. WiiyLEM et MINNE. La traite peut-elle fournir du lait asep-
tique? Rev. Gen. Lait, 4e Annexe, 1904, No. 6, p. 121.

69. WIU.EM et MiELE. Essais de traite aseptique. Rev. Gen. Lait,
4e Annee, 1905, No. 18, p. 409.

70. WII.I.OUGHBY. Milk, its production and uses. Ivondon : Charles
Griffin & Company, Ltd., 1903.

71. WINSI.OW. The production and handling of clean milk. New
York: Wm. R. Jenkins Co.

CHAPTER II.

CHANGES IN MILK CAUSED BY BACTERIA.

Significance of bacterial contamination. The mere consid-
eration of the multiple sources of contamination of milk, em-
phasizes the truth of the statement that freshly drawn milk
contains a wide variety of bacterial forms. Certainly no food
used so universally by man is exposed during its preparation
to a greater variety of contaminating influences. The signifi-
cance of these bacteria in the subsequent changes in milk de-
pends upon their character, adaptability for. existence in milk,
and upon the conditions under which milk is kept. The pre-
cautions exercised in restricting the growth of bacteria are of
greater importance in controlling the character of the milk
when consumed, than those exercised to prevent the initial
contamination. The results of changes of bacterial origin in
milk, concern not merely the commercial requirements that
it must be unaltered in taste and appearance when consumed,
but also have a direct bearing upon the hygiene of food.

The constituents of milk and the form in which they exist,
together with the temperatures to which milk is exposed, offer
conditions favorable to the growth of quite a variety of bac-
terial groups. The carbohydrates represented by the milk
sugar are present in solution, a most favorable form for bac-
terial nutrition. The albuminous constituents, either in solu-
tion or in a finely divided state in suspension, are likewise
freely available to satisfy bacterial requirements.

Fat alone, of the constituents of milk, resists the action of
the common bacteria found in milk. When consideration is
paid to the rapidity of the growth of bacteria, and to the fact
that decomposition of organic matter is the chief function of
bacteria as a class, the full significance of the vulnerability of
milk becomes apparent.

24 CHANGES IN MILK CAUSED BY BACTERIA.

Under favorable conditions of food, temperature, environ-
ment, etc., the possibilities of bacterial multiplication are enor-
mous. The temperatures to which milk is exposed in the
summer, when not refrigerated, are highly favorable to their
multiplication.

Numbers of bacteria in market milk. Hill and Slack (19)
have tabulated results of examination of 2,394 samples of milk
in Boston, covering a period of four months (June to Sep-
tember), with results as follows :

TABLE I.
BACTERIA IN BOSTON MILK. Per cent.

Below 100,000 bacteria per cc. ... 42.

Between 100,000 and 500,000 per cc. ..'. ... 29.75

Between 500,000 and 1,000,000 per cc.. 9.75

Between 1,000,000 and 5,000,000 per cc. ... .. 12.75

Above 5,000,000 per cc... 5.
Uncountable plates ' 75

These figures are not exceptionally high, but are good as
compared with others. Bacterial counts running into the
millions are common in hot weather. Rosenau (34) found
that the milk of Washington, D. C., averaged 22,134,000 bac-
teria per cc. in 1906 and 11,270,000 per cc. in 1907 during the
months of July, August and September. This 'writer gives a
resum£ of results of similar work done elsewhere.

Effect of temperature on bacterial growth. At 1°C. (34°F.)
bacterial growth is very powerfully restrained for awhile. Milk,
after six or eight days at this temperature, may show less bac-
teria than when freshly drawn. The circumstance is attribut-
able to the "germicidal " phenomenon of milk. Pennington
(32) in the study of samples of milk kept for long periods at
1°C. found that certain bacteria multiply at that temperature.
In time the numbers may run into the millions per cc. The
species belonged to the group of organisms capable of acting on
protein, without affecting the appearance of the milk. These
observations were made upon the best milk obtainable, as well
as upon poor milk. It must be concluded that cold storage
cannot be relied upon to keep milk indefinitely. At 10°C.
(50°F.) milk may be kept for two or three days without an

EFFECT OF TEMPERATURE ON BACTERIAL GROWTH. 25

increase in numbers, and those growing at that temperature
not lactic acid bacteria. At 20°C. (68°F.) milk sours in forty
hours. At 37°C. (99°F.) curdling occurs in a few hours (ll).
The length of time required for transportation and delivery of
milk is frequently such that refrigeration must be used to insure
its reaching the consumer in proper condition.

Methods of cooling. Some of the methods on the farm are
crude and inefficient. The process of passing mrlk through
the air to remove undesirable odors — aeration — will accomplish
some reduction of temperature. Cans of milk may be stood
in a tank of water, and by stirring the milk occasionally the
temperature may be reduced. In a hot dry climate cans may
be covered with burlap and dampened. The evaporation from
the burlap will lower temperature. In the same way, wet
blankets over cans on a wagon are of use.

There are various mechanical devices for utilizing cold water.
These fail in hot weather, when most needed. The use of ice
with proper apparatus is productive of better results, and is
essential in hot weather. The use of ice constitutes the stand-
ard, approved method of cooling milk on the small dairy farm,
in climates where natural ice may be obtained.

Mechanical refrigeration, by means of anhydrous ammonia or
carbon dioxide, furnishes the most efficient means for preserv-
ing milk in large quantities (38). It is employed in city
distributing depots, and in the best large dairies. It may, and
should, be very widely used in connection with dairies in warm
climates.

Milk during transportation. The refrigerator car, with
abundant ice supply, solves the problem of shipping milk long
distances in tanks. It is not so effective for local traffic, when
the car doors are frequently opened.

Bottles of milk in crates may be kept in good condition for
quite a time without a refrigerator car, by packing cracked ice
about them. Bottles of certified milk, packed in closed wooden
boxes, perhaps metal lined, and thoroughly surrounded with
cracked ice, may likewise be shipped. Milk in cans covered
with non-conducting jackets of hair may be kept cool longer
than otherwise (4, 14, 43, 44).

26 CHANGES IN MILK CAUSED BY BACTERIA.

Preservation by chemicals. Bacterial changes in milk or
cream may be retarded by the addition of various' chemicals,
such as borax, formalin, and others. They are substitutes
for cleanliness and refrigeration, besides being undesirable
constituents of an article of food. Their use in milk has been,
and needs to be, very vigorously opposed by pure food laws.
The campaign against the use of milk preservatives has been
very effective. The result has been an increase in the use
of another method for compensating for deficiencies in the
care of milk, that is, commercial pasteurization. Budde has
suggested a method of preserving milk by the addition of
hydrogen peroxide, which is ver}^ readily removed from milk
by heating. The scheme has not received serious consideration.
The matter of the use of preservatives and their detection, is
discussed in Chap. XI. The changes in milk constitute a
complex biochemic problem, but certain of the more common
ones may be discussed in a systematic manner.

Lactic acid fermentation. The souring of- milk is the mani-
festation of the commonest of fermentative changes in milk.
As a result of bacterial activities the lactose is transformed
into lactic acid, which compound is responsible for the char-
acteristic flavor and curdling of soured milk. A considerable
number of bacteria are capable of inducing the change, but
it has been shown that a very small group of organisms are
ordinarily found in milk when souring is well advanced. In
fact, one of these, Bad. lactis acidi, may be regarded as
the typical lactic acid organism. It has been found in nu-
merous examinations made of milk from widely separated
quarters of the United States. Its identity with the lactic acid
organism described by L,eichmann in Europe has been estab-
lished and this fact adds strength to the view that it may be
regarded as the common lactic acid organism. This organism
has been classified as a rod form (bacterium) because the indi-
vidual cells are usually longer than broad. It forms chains
of greater or less length and in bouillon culture sometimes
appears as chains of undoubted micrococci. Streptococcus lac-
ticus Kruse is another widely distributed organism observed
to predominate in souring milk. Some writers have insisted

LACTIC ACID FERMENTATION. 27

upon abandoning the use of the name Bad, acidi laciici L,eich-
mann on the ground of the identity of the organism with
Streptococcus lacticus Kruse. The discussion illustrates the
difficulties of bacterial classification and has certainly empha-
sized the fact of the common occurrence in milk of strep-
tococci and other forms almost indistinguishable from them.
Members of the B '. laclis aerogenes and B. colt communis (37)
groups are capable of causing souring of milk, but require a
temperature near that of the animal body in order to flourish
and become a factor in the souring process. The fact that one
species of lactic acid producing organism may predominate in
milk in which the fermentation is well advanced, is surely an
evidence that the species in question is best fitted to survive.
In the earlier stages of fermentation a greater number of species
participate, but gradually succumb in the competition on
account of intolerance to acid, other bacterial products, or
other environmental conditions. It has been shown that a cer-
tain non-acid producing organism, by some means, creates con-
ditions more favorable to Bact. acidi lactici, and contributes to
the more rapid souring of milk than would occur without its
presence (25, 26). The growth of lactic acid organisms in
souring milk is not unlimited, for eventually their multipli-
cation is checked by the product of their own growth — lactic
acid.

The lactic acid organism owes its pre-eminence in milk to its
thorough adaptation to the environment in competition with
other organisms. In fresh milk it forms a small percentage of
the bacteria present. At 10°C. (50°F.) it multiplies slowly,
gaining no advantage over competitors, but at 20°C. (68°F.)
it predominates. At this latter temperature milk is curdled in
forty hours.

The lactic acid fermentation is deleterious in the sense that
the result of its progress terminates the period during which
milk is a salable food product. When milk for domestic pur-
poses sours sooner than usual, the blame is laid upon the dealer.
This fermentation produces manifestations in the taste and ap-
pearance of the milk easily recognized by the consumer and
in the popular mind is an index of the keeping quality of the

CHANGES IN MILK CAUSED BY BACTERIA.

product. Its occurrence naturally furnishes the principal com-
mercial incentive, and almost the only such one that milk
dealers have, to exert efforts to improve the quality of milk as
regards bacterial content.

The attitude of the buttermakers and cheesemakers towards
the lactic acid fermentation is quite the reverse. The forma-
tion of lactic acid is as yet a necessary step in the manufacture
of both butter and cheese. The maintenance of temperature
conditions favoring the fermentation is an important detail in
the manufacture of both products.

That sour milk is, or the organisms causing it are, harmful
to the average normal adult cannot be maintained. On the
contrary, soured dairy products frequently form an article of
diet, as for example, buttermilk and plain sour milk. Metch-
nikoff has laid emphasis upon the value of sour milk as an
article of diet (28).

The importance of the lactic acid fermentation has occas-
ioned considerable experimental work to determine the source
from which the bacteria commonly gain access to milk. The
existence of bacteria within the udder has suggested a study
of those organisms with reference to the possible presence of
that one among them. They have been isolated a few times
from cultures made direct from the glandular tissue of freshly
slaughtered animals. Extensive examinations of the bacterial
flora of milk drawn with aseptic precautions have shown them
in such few instances that their presence in those particular
samples was regarded as an accidental contamination from
sources other than the interior of the udder. For instance, in
a series of two hundred and five samples, taken from seventy
cows during several days, the organism was found in only
eight instances (7). Examinations of the stable air and the
dust shaken from the animal during milking have shown the
constant presence of Bad. acidi lactici. The conclusion follows,
that milk is contaminated with the lactic acid organisms while
being drawn, and that the interior of the udder is of no im-
portance as a source. The observations made did not include
the influence of dirty utensils containing souring milk, which,
of course, is a factor, the importance of which is obvious.

PUTREFACTIVE PROCESSES. 29

Putrefactive processes. The decomposition changes of the
casein and albumen of milk by bacterial action are less notice-
able than the decomposition of milk sugar, but more important
from a hygienic point of view. Such alteration of nitrogenous
compounds is designated putrefaction, and in the process the
milk assumes an alkaline reaction. Among the direct products
of the bacteria, or decomposition products of nitrogenous com-
pounds produced by them, are some that produce toxic effects
in man. The changes under ordinary conditions are not such
as to callthe attention of the consumer to the condition, as in
the case of soured milk.

Organisms causing putrefaction. As in the case of the lactic
acid fermentation, a great number of species are capable of
inducing putrefaction. The organisms are frequently spore
bearers, and when cultivated on gelatin usually cause lique-
faction of that medium. The change is induced by enzymes
elaborated by the organisms and acting thereafter quite inde-
pendently of them. This action is illustrated in gelatin by
the area of liquefaction surrounding the growth of the organ-
ism. In milk the action on the nitrogenous- constituents may
or may not be preceded by a curdling of the milk by enzyme
action. Milk poorly cooled in hot weather will sometimes
curdle, showing a weakly acid or alkaline reaction, due to
enzyme action. The group of organisms of which Bacillus
subtilis is the type is a common representative of the . putre-
factive organisms.

Antagonism of lactic acid fermentation. The active progress
of putrefactive changes does not occur under conditions favor-
ing the souring of milk, for the rapid multiplication of the
lactic acid organisms creates conditions unfavorable for putre-
faction (5). In this sense, souring may be considered as a
beneficent process, protecting milk against a worse decomposi-
tion.

Conditions controlling putrefaction. Putrefactive organisms
are able to multiply at temperatures somewhat below 20° C.
more rapidly than the lactic acid organisms. Hence, milk
kept at low temperatures is more apt to undergo putrefaction
than souring. The point should be made that at such tempera-

30 CHANGES IN MILK CAUSED BY BACTERIA.

tures putrefaction goes on slowly, so that this circumstance is
of no practical importance in the care of milk as customarily
kept for consumption. A very old milk, however, even though
it has been kept at 12°C. and not sour, may not be free from
the products of putrefaction.

Source of putrefactive organisms. The dust of stable air,
and particularly the filth dropping into the milk pail from the
udder and flanks of the cow, certainly contribute liberally to in-
fection by putrefactive organisms. Poorly cleansed milk uten-
sils and polluted water deserve mention. In fresh milk these
organisms greatly outnumber the lactic acid organisms.

Toxic milk. There are 011 record a few cases of poisoning
believed to have been due to the elaboration of toxic substances
by bacteria in milk. Very little is known about the topic.
Kastle (21) has made a summary of the subject and has col-
lected a bibliography.

Ropy milk. None of the faults of milk arouse the distrust
of the consumer more than the viscid condition of milk and
cream, popularly designated "ropy." The widespread abhor-
rence of milk in this condition is induced by the belief that
it is the product of a diseased udder. The false inference
is encouraged by the fact that dairymen sometimes refer to the
milk of an inflamed udder as "ropy" or "stringy." There
is no relation between the two and no real confusion beyond
that induced by the double significance of the word ropy.
There is no ground for attributing a harmful result from the
consumption of the ropy milk delivered to customers, but the
occurrence of the trouble menaces the success of a milk route
by occasioning loss of custom.

The viscid condition appears not sooner than twelve hours,
but sometimes as late as thirty hours, after milking. Further-
more, it is most readily observed in milk that has stood undis-
turbed for several hours, during which period the cream has
risen. These conditions give the false impression that the
trouble is only associated with cream, while, in fact, skim
milk is just as susceptible to the trouble. The consistency of
cream does, however, accentuate the viscosity. Fig. 5 shows
the behavior of ropy cream when lifted with a fork.

ROPY MILK.

31

Cause. of ropy milk. The condition is brought about by the
presence of Bacillus lactis viscosus, described first by Adametz
(l). The individual bacteria possess enveloping masses of

slimy viscid material,
which impart a similar
characteristic to the
milk when they are
present in sufficient
numbers. Fig. 6
shows the ropy milk
organisms. The cap-
sules of viscid sub-
stance are represented
by white areas sur-
rounding each cell.

Many organisms ca-
pable of inducing vis-
cosity when grown in
milk, under various
conditions, have been
described . Advances
in methods of identi-
fying bacteria make it
impossible to say how
many of these organisms are
really identical. The more re-
cent studies of the occurrence
of ropy milk in dairies in North
America and Europe, point to
the conclusion that B. lactis
viscosus is very largely the cause
of the trouble. The ropy milk
organisms isolated by the writer
have always been of this species
(42) . Harrison has found some
different species (16).

Fig. 5. Ropy cream lifted with a fork

Fig. 6. Bacillus lactis viscosus,
from a milk culture (42).

32 CHANGES IN MILK CAUSED BY BACTERIA.

Biological characteristics of B. lactis viscosits. The organism
has been isolated from water, which is considered its natural
habitat. Growth is fairly luxuriant at 15° C. (59° F.), best
at 25° C. (77° F.) and very slight at 37° C. (98° F.). How-
ever, 8° C. (46° F.) is not low enough to inhibit growth. The
organisms multiply rapidly enough in ice water to induce vis-
cosity in milk kept in cans in ice water. That is, this organ-
ism forms an exception to the rule that care in cooling milk
inhibits the multiplication of bacteria. At low temperatures
the ropy milk organisms have a comparatively clear field for
growth, free from serious competition with the lactic acid or-
ganisms. At higher temperatures, such is not the case. B '.
lactis visco'sus will grow only in the presence of air, which ac-
counts for the appearance of viscosity first on the top of milk.
This biological peculiarity is doubtless the reason that ropy
milk is never, or rarely, seen in bottled milk. The organism
does not form spores, and is killed in culture by exposure to
58° C. (136° F.) for ten minutes (16, 41).

Sources of contamination of milk. The fact that B '.. lactis vis-
cosus grows with great difficulty at blood heat, effectually dis-
poses of any suspicion that ropy milk is the result of disease
in the cow. Water must be regarded as the original source of
trouble, but it may by no means be the immediate one. The
cow may, sometimes, carry the organisms on the hairy coat,
from water to the milk. Several observers have isolated ropy
milk organisms from stable air. When ropy milk is causing
trouble, the organisms are found with great frequency in sam-
ples taken from the floor dust of milk rooms. The practice of
cooling cans of milk nearly immersed in a vat of ice water af-
fords, in the milky water, favorable conditions for the multi-
plication of the organisms and for the contamination of the
milk by them. The spattering of water, incident to moving
cans or adding ice, gives opportunity for the contamination of
the milk. The corrugated milk cooler, containing water in
circulation, may have a leak, giving opportunity for direct
contamination from water. The practice of merely rinsing
utensils at night and using them in the morning without scald-
ing, gives another opportunity for bringing water into contact

ROPY MILK. 33

with the milk. Unclean utensils constitute the greatest factor
in the contamination of milk. The wire mesh strainer, parti-
ally clogged with filth, may be the only visible evidence of
carelessness. Bacteriological examination of the supposedly
clean utensils will reveal the presence of ropy milk organisms
in a large percentage of examinations. This is most readily
done by pouring separate samples of sterilized milk into the
various suspected utensils and then immediately out again.
These samples kept at a low temperature for several days will
become viscid if they have been in contact with the bacteria
of ropy milk. Attention to the technic of washing utensils
will reveal the fact that the scalding is not carried out in accord-
dance with the bacteriological requirements governing the prac-
tice. Carelessness in this regard is by no means limited to
farmers with poor scalding equipment. It is just as frequently
the result of too hasty steaming of cans by employees in large
city concerns, who misuse the abundant facilities for scalding
at their disposal. Gross neglect, therefore, permits the ropy
milk organisms to exist in milk utensils from day to day, to con-
taminate each succeeding lot of milk. Under such conditions
the mill^ strainer, designed to improve the quality of milk,
becomes a potent factor in its deterioration.

Means of corn-bating ropy milk. The control of this milk
fault is a comparatively simple matter when bacteriological
principles are borne in mind. In most cases the trouble may
be abated by instituting the continued practice of a thorough
scalding of every utensil with which milk comes in contact.
In the absence of steam, immersion in boiling water for three
to five minutes will serve the purpose. Milk cans too large
for immersion in the vessel at hand may be filled with boiling
water and should be left filled for five minutes. As a pre-
caution against dust contamination, pails and cans, after clean-
ing, should be stood bottom side up. Strainers, coolers, etc.,
should likewise be protected in some manner. In most cases
the dirty wire strainers may be replaced by cheesecloth strain-
ers. The sources of contamination from water are easily
remedied. The location of the source from which contamin-
ation is derived may be determined by taking samples of milk

34 CHANGES IN MILK CAUSED BY BACTERIA.

at various stages in the handling, and watching for the appear-
ance of ropiness after the milk has stood a day in a cool place.
Frequently it will be found that the milk as it comes from the
stable is normal and that the source of contamination is in the
milk room. If such is not the case, the dampening of the
udders of the cows, before milking, will be necessary (41, 42).

Germicidal activity, When samples of freshly drawn milk
are examined at frequent intervals for numbers of bacteria, the
fact becomes evident that the total numbers do not immediately
begin to increase. The numbers may decrease or remain sta-
tionary for a period before the increase of bacteria begins.
Immediate increase of total numbers is distinctly the exception.
The phenomenon varies in degree in the milk of individual
cows (20).

Kunze (22) determined the number of bacteria in milk when
freshly drawn, after thorough cooling, after sixteen hours at
6-8°C. and after forty hours at 6-8 °C. He averaged the results
of 35 samples collected at periods covering a whole year. The
freshly drawn milk was very clean, averaging only about four
hundred colonies per cc. Thorough cooling alone reduced the
original count by 11.4% . After sixteen hours at 6-8° C. it was
reduced by 16.8%. At forty hours the count was 33.09% of
the original, a reduction of 21.69% from the count taken just
after cooling.

The length of the period of decline, in any case, is governed
by the temperature at which the milk is kept. For instance,
at 37°C. (98°F.) the period las'ts about three hours ; at 21°C.
(70°F.), three to twelve hours ;* at 13°C. (55°F.), about twenty-
four hours; at 4°C. (40°F.), forty-eight hours; at 1°C. (34°F.),
six to eight days.

The temperature governs the extent of decrease. At 70°F.
the decrease is marked, frequently 50% or more in market
milk. At 55°F. it is less marked, and at 40°F. still less.
These observations are presented in a graphic way in Fig. 7.
The chart (Fig. 7) shows the changes in the number of bac-
teria in three portions of the same original sample of milk,
kept at different temperatures. The sample was drawn from
the cow with the strictest aseptic precautions.

36 CHANGES IN MILK CAUSED BY BACTERIA.

The germicidal action is observed in samples drawn so care-
fully that none but the micrococci from the interior of the
udder are present, as well as in samples of highly contaminated
market milk. The fact that the greater decrease in milk con-
taining only udder micrococci occurs at 70°F., rather than at
40°F., is of interest. The explanation has been advanced very
recently (22) that these organisms die off in refrigerated milk,
because the temperature is so different from that to which they
are accustomed. The theory does not harmonize all the facts
observed in connection with the phenomenon.

The germicidal action of milk is destroyed by heat, being
stopped completely by 176°F. for forty minutes. Milk heated
to the same temperature for twenty minutes shows no decrease
of the milk bacteria freshly implanted in it, and no increase for
several hours. Similarly 149°F., for forty minutes, resulted
in the restraint of growth for nine hours. Exposure to 131°F.
for thirty minutes, or 140°F. for twenty minutes, has been
sho\vn to destroy the germicidal activity of milk against B.
lactis aerogenes, but had no influence upon its action on B.
typhosus.

Fresh milk, drawn with aseptic precautions and planted with
pure cultures of various pathogenic organisms, has shown a
decrease in colonies in plate cultures, while sterilized milk has
shown an immediate increase. Among the organisms tested
are the germs of typhoid, cholera, diphtheria, dysentery and
B. lactis aerogenes, a common lactic acid producer (35).

A given sample of milk may show a selective specific action
with reference to its restraining action on different organisms.
In a given sample one organism may immediately multiply,
while another may not. It has been shown that the common
lactic acid organisms in market milk usually increase from the
beginning even when other forms are disappearing so rapidly
that the total numbers are decreasing. It has been suggested
that the leucocytes in milk destroy the bacteria by phagocy-
tosis. This does occur to some extent, but it has been shown
that it is not responsible for the great changes observed (35).

Some recent studies go to show .that the decrease is more
apparent than real. Agglutination occurs, and, with the mod-

GKRMICIDAL ACTIVITY. 37

erate- agitation of making dilutions for plate cultures,* these
clumps would remain undisturbed (35). Thus, the number
of colonies on the medium would decrease, while plates made
from milk that had been most violently agitated would show
an increase. This gives a reason for the discrepancies between
the results of various workers, and goes a long way toward
explaining the phenomenon.

It has been generally assumed by writers on the subject,
that the decrease in numbers of colonies on plates indicated
the death of the organisms concerned. Most writers consid-
ered this due to some germicidal property of milk. It has been
suggested that many organisms die off in milk because they
find there an environment wholly unsuited to them. This is
undoubtedly true to some extent, but hardly accounts for some
of the latest observations published. Agglutination seems to
account for a large part of the apparent decrease in numbers.
Even making allowance for this, it is evident that raw milk
exerts a restraining influence on the multiplication of bacteria
as compared with heated milk. In the light of this view, the
phenomenon might be described as similar to the action of a
weak antiseptic (35).

The evidence at hand does not warrant recommending a
change in the general practice of rapid cooling of milk. That
is, it has not been proven that delay in cooling would improve
the keeping quality. It is certain, though, that the phenom-
enon should be taken into consideration in judging the success
of efforts to secure germ-free milk. The length of time after
milking, and the temperature, should be taken into consider-
ation when various bacterial determinations are compared, and
submitted as evidence of success in aseptic milking. For
instance, the work reported in Ref. 69, Chap. I, was appar-
ently done without recognition of this important factor.

* The common method of counting bacteria is described in Chap. VIII.

38 CHANGES IN MILK CAUSED BY BACTERIA.

REFERENCES.

1. ADAMETZ. Untersuchungen iiber Bacillus lactis viscosus, einen
weit verbreiteten niilchwirtschaftlichen Schadling. Landw. Jahrb., Ber-
lin, 1891, S. 175.

2. ADAMETZ. Centbl. Bakt. , etc., 2. Abt., Bd. VI, 1900, No. 12, S. 406.

3. AI.VORD and PEARSON. The milk supply of two hundred cities
and towns. Bui. No. 46, Bur. Anim. Ind., V. S. Dept. Agr., 1903.

4. BERLINER. Milk during transportation. Cir. Xo. 114, Bur. Anim.
Ind., U. S. Dept. Agr., Washington, D. C., p. 27.

5. BOUSKA. Studien iiber den Antagonismus zwdschen Milchsaurefer-
menten und Bakterien der Gruppe des Bacillus subtilis. Landw. Jahrb.
Schw., 1903.

6. BURR. Investigations on the sources of the acid organisms con-
cerned in the souring of milk. Thirteenth Ann. Rept. Starrs Agr. Exp.
Sta., Storrs, Conn., 1900, p. 66.

7. BURR. The source of the acid organisms of milk and cream.
Centbl. Bakt., etc., 2. Abt., Bd. VIII, 1902, No. 8, S. 236.

8. CONN. Bacteria in milk and its products. Philadelphia: P. Bla-
kiston's Son & Co., 1903.

9. CONN. The relation of temperature to the keeping quality of milk.
Bui. No. 26, Storrs Agr. Exp. Sta., Storrs, Conn., 1903.

10. CONN and ESTEN. The comparative growth of different species
of bacteria in normal milk. Fourteenth Ann. Rept. Storrs Agr. Exp.
Sta., Storrs, Conn., 1901, p. 13.

11. CONN and ESTEN. The effect of different temperatures in deter-
mining the species of bacteria which grow in milk. Sixteenth Ann.
Rept. Storrs Agr. Exp. Sta., Storrs, Conn., 1904, p.* 27.

12. CONN, ESTEN and STOCKING. A classification of dairy bacteria.
Eighteenth Ann. Rept. Storrs Agr. Exp. Sta., Storrs, Conn., 1906,
p. 91.

13. CONN and STOCKING. Studies concerning the so-called germi-
cidal action of milk. Rev. Gen. Lait, Vol. II, Nos. 12 and 13.

14. DOANE. Economical methods for improving the keeping quali-
ties of milk. Bui. No. 88, Maryland Agr. Exp. Sta., College Park,
Md., 1903.

15. DOANE. The milk supply of twenty-nine southern cities. Bui.
No. 70, Bur. Anim. Ind., U. S. Dept. Agr., Washington, D. C., 1905.

16. HARRISON. The viscous fermentation of milk and beer. Trans.
Roy. Soc. Canada, Second Series, 1905-1906, Vol! XI, Sec. IV, p. 71.

17. HEINEMANN. The significance of streptococci in milk. Jour.
Infect. Diseases, Vol. Ill, 1906, No. 2, p. 173.

REFERENCES. 39

18. HEINEMANN. The kinds of lactic acid produced by lactic acid
bacteria. Jour. Biol. Chem., Vol. II, 1907, No. 6, p. 603.

19. HILL and SLACK. Bacterial counts of Boston's milk supply.
Amer. Jour. Pub. Hyg. and Jour. Mass. Assoc. Bds. Health, Vol. XIV,
1904, No. 4, N. S. Vol. I, No. 1, p. 236.

20. HUNZIKKR. Investigations concerning the germicidal action in
cow's milk. Bui. No. 197, Cornell Univ. Agr. Exp. Sta., Ithaca, N. Y.

21. KASTLE. The chemistry of milk. Bui. No. 41, Hyg. Lab., U.
S. Pub. Health and Mar. Hosp. Sen'., Washington, D. C., 1908, p. 309.

22. KUNTZK. Gewinnung keimarmer Milch. Centbl. Bakt., etc.,
2. Abt., Bd. XX, Nos. 12 und 14, S. 420.

23. IvOHNis. Versuch einer Gruppierung der Milchsaurebakterien.
Centbl. Bakt., etc., 2. Abt., Bd. XVIII, S. 97.

24. MARSHALL. Ropiness in milk. Bui. No. 140, Mich. State Agr.
Col. Exp. Sta., Agricultural College, Mich., 1897.

25. MARSHALL. A preliminary note on the associative action of bac-
teria in the souring of milk and in other milk fermentations. Special
Bui. No. 23, Mich. State Agr. Col. Exp. Sta., Agricultural College,
Mich., 1904.

26. MARSHALL. Extended studies of the associative action of bac-
teria in the souring of milk. Special Bui. No. 33, Mich. State Agr. Col.
Exp. Sta., Agricultural College, Mich., 1905.

27. MARSHALL and FARRAND. Bacterial associations in the souring
of milk. Centbl. Bakt., etc., 2. Abt., Bd. XXI, No. 1, 1908, S. 7.

28. METCHNIKOFF, trans, by Mitchell. The prolongation of life. N.
Y. and London : G. P. Putnam's Sons, 1908.

29. MOORE. Bacteria in milk. Circular published by the Commis-
sioner of Agriculture of New York, Albany, 1902.

30. MiJLLER. Vergleichende Untersuchungen iiber Milchsaurebak-
terien (des Typus giintheri) verschiedener Herkunft, nebst Beitrag zur
Frage der Stellung dieser Organismen zu den typischen Streptokokken.
Centbl. Bakt., etc., 2. Abt., Bd. XVII, S. 468.

31. PARK. The great bacterial contamination of the milk of cities,
can it be lessened by the action of health authorities? New York Uni-
versity, Bui. Med. Sci., Vol. I, 1901, p. 71.

32. PENNINGTON. Bacterial growth and chemical changes in milk
kept at low temperatures. Jour. Biol. Chem., Vol. IV, 1908, Nos. 4 and
5, p. 353.

33. REVIS. The acid coagulation of milk. Jour. Hyg., Vol. 7, p. 216.

34. ROSENAU. The number of bacteria in market milk and the value
of bacterial counts. Bui. No. 41, U. S. Pub. Health and Mar. Hosp.
Sen>., Washington, D. C., 1908, p. 421.

40 CHANGES IX MILK CAUSED BY BACTERIA.

35. ROSENAU and McCov. The gerniicidal property of milk. Bui.
No. 41, Hyg. Lab., L\ S. Pub. Health and Mar. Hosp. Sen>., Washing-
ton, D. C., p. 449.

36. RUSSELL. Outlines of dairy bacteriology. Madison, Wis.: H. Iv.
Russell, 1899.

37. SAVAGE. The coagulation of milk by Bacillus coli communis.
Jour. Path, and Bad., Vol. 10, 1908, p. 90.

38. STEWART and ATWOOD. Bacteria in milk and artificial refriger-
ation for dairymen. Bui. No. Ill, West Virginia I 'nil'. Agr. Exp. Sta.,
Morgantown, W. Va., 1908.

39. ST. JOHN and PENNINGTON. The relative rate of growth of milk
bacteria in raw and pasteurized clean milk. Jour. Infect. J)is., Vol. IV,
1907, No. 4, p. 647.

40. STOCKING. The so-called germicidal property of milk. Bui. No.
37, Storrs Agr. Exp. Sta., Storrs, Conn.

41. WARD. Ropiness in milk and cream. Bui. No. 165, Cornell
Univ. Agr. Exp. Sta., Ithaca, N. Y., 1899.

42. WARD. Further observations upon ropiness in milk and cream.
Bui. No. 195, Cornell ('nil'. Agr. Exp. Sta., Ithaca, N. Y., 1901.

43. WHITAKER. The milk supply of Boston and other New England
cities. Bui. No. 20, Bur. Anim. /m/., (\S. Dept. Agr., Washington,
D. C., 1898.

44. WHITAKER. The milk supply of Boston, New York and Phila-
delphia. Bui. No. 81, Bur. Anim. hid., ( '. S. Dept. Agr., Washington,
D. C., 1905.

45. WOLF. Zur Kenntnis der Veranderungen in der Bakterienflora
der frischen Milch wahrend der sogennanten Inkubatioiisstadiums.
Centbl. Bakt., etc., 2. Abt., Bd. XX, 1908, No. 18, S. 545.

CHAPTER III.

EPIDEMIC DISEASES TRANSMITTED BY MILK.

Transmission of diseases of man by milk. Milk traffic as
now constituted, offers a particularly favorable channel for
the transmission of certain diseases of man. The close con-
tact of human beings incident to the handling of milk at the
producing dairies, coupled with the general lack of observance
of aseptic precautions in the work, offer frequent opportunities
for contamination of the product. Milk offers conditions that
are not unfavorable to the bacteria of typhoid fever and diph-
theria, and they may even multiply therein. The unrecog-
nized virus of scarlet fever likewise finds conditions favorable.

The wide use of milk among households gives opportunity
for very broad distribution of infection through milk. The
output of a dairy may not go to the same consumers from day
to day, so the field for the possible infliction of damage by a
dairy is yet more widened.

Character of milk-borne epidemics* The large well-marked
epidemics borne by milk are characterized by the almost sim-
ultaneous appearance of cases among patrons of the milk route.
Variations occur, due to individual idiosyncrasy with respect
to the incubation period of the disease. As likely as not the
primary cases, attributable to the milk, will cease to occur as
suddenly as they began. L,ater, there will be observed second-
ary cases among members of the same or different households.
The causative relation of milk stands out most clearly in out-
breaks derived entirely from milk, and not complicated by the
concurrent presence of the disease due to other quite different
channels of dissemination (18).

Very thorough study of reported cases of typhoid and diph-
theria in a city, with reference to the milk supply, have led to
the conclusion that milk is responsible for many isolated cases

42 EPIDEMIC DISEASES TRANSMITTED BY MILK.

of these diseases. That is to say, these diseases may occur as
a result of contaminated milk, and escape notice ordinarily.

Typhoid fever. Typhoid is the most common of the epi-
demic type of infectious diseases. Little by little it is be-
ginning to be recognized that milk stands next to water as a
means for spreading infection. In this connection it is inter-
esting to note that typhoid fever is relatively more prevalent
in rural districts than in cities. Fulton has collected the fol-
lowing figures, quoted by Whipple (38) :

TABLE II.
TYPHOID FEVER IN URBAN AND RURAL POPULATIONS.

Av. % of Av.
rural typhoid
popula- rate per
tion. 1000.

5 states with urban population of more than 60 % of total

30 ....

.... 25

6 "

of 40 to 60% of total....

49 ...

.... 42

7 "

of 30 fo 40 % of total ....

67 ....

.... 38

8 "

of 20 to 30% of total

75 ....

... 46

12 "

of 10 to 20% of total

87 ....

.... 62

12 "

of 0 to 10% of total

95 .:..

.... 67

Investigations in the District of Columbia. During the past
two years very thorough investigations have been made of the
source of infection of the typhoid fever cases occurring in the
District of Columbia during the months May to October in-
clusive. The work was instituted in consequence of the obser-
vation that the installation of a satisfactory system of water
filtration did not produce a satisfactory lowering of the typhoid
fever rate. In 1906 it was possible to definitely assign a source
of infection in the case of only 18.6% of all reported cases
believed to have originated in the District'. Among these,
11.3% of all were attributed to milk and 7.3% to contact.
That is, 60.8% of all traceable cases were milk-borne. In 1907,
the figures were : traceable to milk, 9. 18% ; to contact, 19.50% ;
total accounted for, 28.68% . In that year 32c/c of all traceable
cases were attributed to milk.

TYPHOID FEVER. 43

The careful study of the cases of typhoid fever in the Dis-
trict of Columbia with reference to the source of the milk, has
made it possible to compile figures showing the amount of that
disease traceable to each dealer. The results appearing in the
reports (28, 29) on the work are rearranged in the appended
table.

In 1906 definite outbreaks of typhoid fever were attributed
to dairies No. 4 and No. 13. Note the difference in the rate
of typhoid attributed to these dairies in 1907, when no out-
breaks occurred among their customers. In 1907, dairy No.
163 was the source of an outbreak.

Dairy No. 10 makes-a very fine showing during both seasons,
attributed to the fact that efficient methods for sterilizing the
bottles and for pasteurizing the milk were used. The good
showing of dairy No. 17, in 1908, may be attributed to the
fact that an efficient method of sterilizing bottles was used and
to the fact that a portion of the milk was derived from a special
dairy. Suspected outbreaks were attributed to dairies Nos. 8,
44 and 46 in 1907.

The work on typhoid fever in the District of Columbia led
Rosenau, Lumsden and Kastle to the conclusion that infected
milk is one of the important known factors in the spread of the
disease there. This view concerning the relation of milk to
the spread of the disease has been expressed by others.

Importance of milk as a carrier. Whipple writes, on page
132 of his book (38):

" In a general sort of way it may be said that in the cities of the United
States, at the present time, about 40 per cent, of the typhoid fever is due
to water, 25 per cent, to milk, 30 per cent, to ordinary contagion (includ-
ing fly transmission), and only about 5 per cent, to all other causes."

Neufeld (22) considers that milk is next in importance to
water as a means for transmitting typhoid fever. Trask (32)
has collected data concerning 317 milk-borne typhoid fever
epidemics. Harrington (13) states that during two years the
Massachusetts State Board of Health investigated 18 local epi-
demics of typhoid fever. Of these, 14 were milk-borne, 3 due
to water, and 1 unexplained. , The importance of milk in con-
nection with typhoid has till lately been underestimated.

TABLE III.

TYPHOID FEVER IN THE DISTRICT OF COLUMBIA WITH REFER-
ENCE TO THE MILK SUPPLY.

May to October inclusive .
1906 1907

Dairy

No.

No.
Cases.

Gallons of
Milk vSold.

No. Cases
per
100, 000 gals.
Milk Sold.

No.
Cases.

Gallons of
Milk Sold.

No. Cases
per
100, 000 gals.
Milk Sold.

Dairy
No.

1

26

142,986

18.2

19

268,724

7.1

1

2

29

134,911

21.5

50

214,030

23.4

2

3

20

119,889

16.6

11

154,963

7.1

3

4

54

102,867

52.5

32

148,352

21.6

4

5

17

77,098

22.0

10

137,516

7.2

5

6

17

71,690

23.7

20

135,044

14.8

6

7

25

71,350

35.0

16

117,365

13.6

7

8

23

62,903

36.6

22

128,800

17.1

8

9

18

51,115

35.2

9

100,800

8.9

9

10

3

44,496

6.7

8

147,107

5.4

10

11

8

43,800

18.2

7

85,558

8.2

11

12

5

39,286

12.7

10

89,240

11.2

12

13

41

35,995

113.9

6

92,602

6.5

13

14

7

31,984

21.9

4

14

15

2

31,542

6.3

5

15

16

4

29,247

13.7

4

49,395

8.1

16

17

5

27,247

18.4

2

38,637

5.2

17

18

7

24,829

28.2

2

42,540

4.7

18

19

9

22,005

40.9

19

20

4

14,145

28.3

20

21

1

13,909

7.2

-

21

22

1

12,845

7.8

22

23

3

11,617

25.8

23

24

3

11,617

25.8

24

25

4

11,304

35.4

25

26

1

11,187

8.9

26

27

0

11,070

0.0

27

28

3

10,836

27.8

28

29

—

29

30

4

9,697

41.2

30

31

4

9,328

42.9

31

32

1

8,320

12.0

32

33

1

7,855

12.8

33

34

1

7,723

12.9

34

35

4

6,028

66.4

35

36

4

5,225

76.5

36

37

1

3,872

25.8

37

38

1

3,182

31.4

38

39

1

3,028

33.0

39

40

1

2,168

46.1

40

41

0

1,353

0.0

41

10

37,440

26.7

44

18

61,399

29.3

46

NOTE : These ratios calculated for the
months of July, Aug., Sept , and Oct. only.

31

10,955

282.9

163

SOURCES OF THE CONTAMINATION OF MILK. 45

Sources of the contamination of milk. The means by which
typhoid fever bacilli are disseminated by the individual offer
frequent opportunity for the infection of milk. The typhoid
patient is believed by some to disseminate the disease during
the incubation period and early stages of the disease. Certain
it is that patients, long before taking to bed, disseminate ba-
cilli through the urine and feces. This is equally true of walk-
ing cases that never take to bed. The danger is augmented
by the fact that diagnosis may be delayed until the second or
third week, and in the mild cases no diagnosis is made, and
thus no warning is given.

The patient in bed is a menace through the careless disposal
of excreta. Thus, infection may be disseminated through the
nurse, by flies when allowed access to discharges on the ground
or in open vaults, and by the contamination of the well or
stream. All these factors may play a part in milk infection
on a dairy farm.

The convalescent may return to work while yet dissemin-
ating infection. A considerable number of those recovering
from typhoid for years afterwards continue to disseminate
infection. Such cases or others harboring bacilli, with no
previous history of typhoid fever, are called bacilli carriers,
and are believed to be significant factors in the spread of the
disease (25). Adequate means for protecting the public from
this source of danger have not yet been put into general prac-
tice.

In the dairy there are certain practices that facilitate the
infection of milk. The failure to wash the hands before milk-
ing and the common practice of wetting the hands with milk
are particularly dangerous. As likely as not the milker may
be acting as nurse in the sick room.

Conditions that would permit flies to come in contact with
milk or the cans are common in dairies.

Common practice in connection with the care of utensils
leaves many opportunities for contamination by polluted water.
Oftentimes, the milking utensils are not scalded after the even-
ing's milking, but are merely rinsed in cold water. The
scalding given utensils is very apt to be inefficient and does

46 EPIDEMIC DISEASES TRANSMITTED BY MILK.

not protect against the dangers of water. Poor scalding is a
serious matter in connection with bottles that may have been
in the sick room. Water may get directly into the milk from
leaks in milk coolers, or by intentional adulteration. The
distributing stations in the city and various places wrhere milk
is sold, furnish their quota of opportunities for the infection
of milk.

Detection of milk-borne typhoid fever epidemics. Milk-borne
epidemics are most quickly detected through a system of ascer-
taining early the facts regarding the possible sources of infec-
tion among the reported cases. The health officer should keep
a card for each dairyman, and post up the cases occurring
among his present patrons, or those that took the milk at any
time within a month previous to attack. An unusual number
will direct attention to the necessity for an investigation (39).
A large proportion of children among those infected would
place the milk supply under particular suspicion.

Bacteriological examinations are not available for antici-
pating milk-borne trouble, nor usually for demonstrating the
presence of the organisms in the milk. The technical diffi-
culties are too great to take up the search for the typhoid
organism in the hope of obtaining decisive useful results. The
same holds true of the examination of water, in connection
with a typhoid epidemic. In the case of both milk and water,
one difficulty lies in the fact that the organisms may not be
present at the time suspicion is aroused. The facts must be
determined by epidemiological evidence. The writer has found
very useful a 3 by 5-inch card printed for the reception of
information on the following points, slightly changed from one
used in working up the Palo Alto epidemic (8).

STATE HYGIENIC LABORATORY.
UNIVERSITY OF CALIFORNIA, BERKELEY.

Patient's name Address

( of first symptoms 19

Date \ of taking to bed ... 19

^of physician's first visit 19

Age sex color nationality

• W r* I V C. K a i | T •

V s

^^iJFORNli^/

SOURCES OF THK CONTAMINATION OF MILK.

47

Place of work, business, or school ........................

Physician while ill ....................................

Health before attack ......................................

Out of town (date)....

Patient discharged by physician (date) ......................

f Chills Pain in Bowels Tongue

] Vomiting Nosebleed Delirium

1 Headache Diarrhoea or Eruption

( Fever Constipation Spleen

0

Constipation

[REVERSE.]
TYPHOID FEVER.

Examination No .......... . .........

Widal reaction :

Made? ........ Date when \ Date when

{Yes or No) Positive) ............ Suggestive

Complications ..............

Drinking Water -™ Milkman

Date when
Negative

Previous cases in the house
Has patient visited other cases?
Privy or water closets.....
What probable sources of infection
What possible sources of infection
Remarks ...

Plumbing

A more elaborate blank for data is employed by the Hygienic
Laboratory, U. S. Public Health and Marine Hospital Service,
in the study of typhoid fever in the District of Columbia (29):

PUBLIC HEALTH AND MARINE HOSPITAL SERVICE — HYGIENIC

LABORATORY.

TYPHOID FEVER CASE CARD.

Date of investigation Case No.

Name

Age....: Color Sex Nationality

Probable date of onset Date of definite symptoms

Name and address of physician :

Residence

Residence in D. C

Residence when taken sick.... ....from ....to

48

EPIDEMIC DISEASES TRANSMITTED BY MILK.

Previous residences... from to

Subsequent residences from to.

Temporary absences from D. C. within 30 days prior

Number of occupants Ages

who have had typhoid When?

Newcomers in house within three months prior

had typhoid ?..„....
Servants —

White: Resident Typhoid?.

Non-resident.. Typhoid?

Colored: Resident Typhoid?.

Non-resident Typhoid?.

Typhoid at homes of servants When?

Disposal of sewage ... W. C. in house.....

W. C. in yard Privy . . Location

General sanitarv condition of residence

OCCUPATION.

Place

Other cases

... from

to

WATER WITHIN 30 DAYS PRIOR.

Solely Principally

Occasionally

FOOD WITHIN 30 DAYS PRIOR.

Where taken

Milk (how used) From ;

Boiled? Pasteurized?

Ice Cream? Where?.

Uncooked fruits and vegetables

Shellfish

CONTACTS.

Association 30 days prior with patients in febrile stage

with suspected cases

with persons who have had typhoid within 6 months

1 year

2 years

3 years :

4 years

5 years ...

Association 30 days prior with persons in contact with patients in febrile

stage.
Treatment of stools and urine of patients

SOURCES OF THE CONTAMINATION OF MILK. 49

Other precautions
Remarks ....

Summary

Signature

In tracing back the milk from the patient to the source, it
will be found that many milk routes may derive their supply
in part or whole from the dairy under suspicion. Record of
the facts is facilitated by making a diagram with lines indicat-
ing the course of the various milk supplies from the producer
to the distributing station and on to the milk routes. At the
dairy under suspicion, the inquiries and observations that
might be made, and corrective measures to be required, are
obvious. A dairy can by no means be freed from suspicion
even if no typhoid patients or convalescents are found there.
Widal tests might bring to light a convalescent from a mild
unrecognized attack. There is always the possibility that the
infection of the milk has resulted from a bacilli carrier and to
detect such a person requires a bacteriological examination of
the feces and urine. A case of infection of milk from a
typhoid bacilli carrier has recently occurred in Washington,
B.C.

Berkeley, Cal., outbreak. A small milk-borne epidemic that
has been brought to the attention of the writer illustrates well
the bad conditions that may prevail (35).

During the last half of October, 1906, there were 20 cases
of typhoid fever reported to the health officer. A study of
the cases with reference to water supply had eliminated that
source of infection from consideration, and information was
secured that many of these cases had very likely been con-
tracted in a nearby city where typhoid was prevalent. Ten
of the cases, reported from October 15th to 29th, were all sup-
plied with milk from the same dealer. The last case of typhoid
on this milk route was a son of the dairyman, who, but a few
days before, had been delivering milk.

A visit to the home where he lay sick revealed dangerous
conditions. No professional nurse was employed. The privy,

50

EPIDEMIC DISEAvSES TRANSMITTED BY MILK.

a temporary affair, had no vault and no protection from flies.
Not ten feet from it, the milk cans were washed in a tem-
porary shed. In this was found a washtub filled with milky
water, indicating that it had recently been used for milk cans.
These conditions are shown in Fig. 8.

Fig. 8. Laundry in which milk cans were washed.

The family washing on the clothes line, and washboard in
the shed by the tub, indicated that the tub was also utilized
for laundry purposes. Some eighteen delivery cans, measures,
etc., were on pegs nearby. Water for scalding cans was heated
over a fire in a small tank, supported by a few bricks. The
supply of water from this source would be ridiculously inade-
quate for the proper scalding of utensils. The general condi-
tions are shown in Fig. 9. The building on which the milk
cans hang contained a case of typhoid fever on the second floor,
besides housing the family, while the basement was used as a
stable. Note in order, from left to right, family washing, tank
for heating water, shed (beyond horse) for can washing, and
privy in fence corner.

DIPHTHERIA. 51

The milk delivered by this dealer, not great in amount, was
not brought to the house before delivery. The cans only were
brought there for washing. It was learned that a carpenter
employed on the premises had recently recovered from an at-
tack of typhoid fever. It is quite possible, too, that the boy
who had been delivering milk may have been disseminating
infection previous to taking to bed. The dairyman was re-
quired to have the can-washing done elsewhere, after which
no further trouble was traceable to the dairy.

Fig, 9. Conditions surrounding a case of typhoid fever,

The milk sold by this dealer was only a fraction of the out-
put of a large dairy, the product of which was mostly sold in
another city, and it was not practicable to trace it. there. A
visit to the dairy and inquiry among physicians near there
revealed no trouble.

Diphtheria. Recorded milk-borne epidemics of this disease
are less common than in the case of typhoid fever. Trask
(32) has collected important data concerning 51 milk-borne
epidemics.

The fact that the conimon seat of the disease is readily
accessible for bacteriological examination, has resulted in the
accumulation of exact information regarding the dangers of
infection.

The clinical case of diphtheria, with a well-defined membrane,
disseminates infection through any means that permit the trans-
fer of saliva. Danger of mfection is not confined however to

52 EPIDEMIC DISEASES TRANSMITTED BY MILK.

the recognized clinical case. During convalescence, the viru-
lent bacilli may persist in the nose or throat for months after
the patient has been discharged as cured, unless the culture
method has been used to determine the time for release from
quarantine. The condition is quite parallel to the typhoid
bacilli carriers. Likewise, diphtheria bacilli may be isolated
from the nose or throat in advance of the appearance of clin-
ical symptoms.

The worst of the matter is the fact that diphtheria exhibits
all degrees of severity down to examples of healthy persons
harboring virulent diphtheria bacilli. These may be quite as
dangerous as the recognized clinical cases. The appearance
of clinical diphtheria in an individual is governed in part by
the state of the resistance of the individual exposed to infection.

The significance of these so-called germ cases is attracting
careful attention in the study of the spread of diphtheria.
They amount to not over 4% of the community in the absence
of an epidemic, but in infected households the percentage of
germ cases rises to 507^ of the individuals exposed. Some
cases are practically always found in families where infection
exists. This class of unrecognized carriers of infection, rather
than the recognized cases under treatment, is regarded as the
chief source for the dissemination of diphtheria in a commu-
nity (16, 36, 37).

In a dairy, a convalescent or germ case may be a milker.
A cough or a sneeze, or any means by which saliva may get
on the hands, and hence to the milk, results in its contamin-
ation with diphtheria. Moore (19) has reported an epidemic
in Ithaca, N. Y., traceable to a convalescent.

Observations tending to implicate the cow as a source of
diphtheria, are not supported by convincing facts (3).

Recognition of milk-borne diphtheria epidemics. Reported
cases must be promptly investigated with reference to the milk
supply, and investigation of the dairy should be made in case
of suspicion. Bacteriological examinations of milk rarely
result in the discovery of Bacillus diphtheriae (2, 7, 20). At
the dairy, inquiry and physical examination of throats should
not be relied upon to the exclusion of taking cultures from both

DIPHTHERIA. 53

throat and nose of all persons about the establishment. The
results will very likely bring" to light facts which may not have
been recognized, or which had been suppressed.

The precautions to be observed upon the detection of diph-
theria in a dairy are obvious. Sale of the milk, raw, should
be interdicted as long as a single person about the place har-
bors diphtheria bacilli. Certainty on this point should be
established by two or three negative cultures at intervals of a
few days, each set being taken simultaneously from the nose
and throat of all individuals concerned. The quickest way to
resume the sale of milk would be to exclude patients and germ
cases from the premises.

Milk-borne diphtheria in Oroville, Cal. The writer has used
cultures to confirm suspicion of a dairy as the cause of an epi-
demic, when no history of clinical diphtheria could be elicited
(34, 35).

Diphtheria was apparently introduced into the town by a
visitor who had recently recovered from the disease elsewhere.
One case was reported on November 14th, shortly after the
arrival of the visitor in the family. No more cases were re-
ported for six \veeks.

From December 25, 1907, until January 25, 1908, cases were
reported in 15 families. Six of these families consumed milk

from the R dairy. One of these 6 families was reported

on December 25th, and the other 5 were reported during the
5 days, January 15th to 20th. Two other families gave a history
of probable spread from the families on the milk route in ques-
tion. Seven infected families in town gave no history of con-
nection with the milk route.

The suspicions of the health officer were directed to the dairy
by the number of infected families who were among its patrons
and by the fact that few families consuming the milk escaped.
A considerable portion of the milk was used by two cheap res-
taurants, and if any cases were contracted from the milk in
these establishments, it was not possible to trace them.

The only people handling the milk were a man, his wife
and daughter. Cultures were made from the nose and throat
of each one. The mother and daughter gave positive cultures

54 KPIDKMIC DISEASES TRANSMITTED BY MILK.

from the throat, while the man gave negative results. Bacilli
persisted in the throat of the woman for three weeks in spite
of constant effort to clear up the infection. No history of
previous clinical diphtheria could be established, nor were clin-
ical manifestations recognizable. The fact that the woman
frequently milked the cows, handled the milk and delivered it,
is of interest. Upon the discovery of the bacilli carriers at
the dairy, the local authorities took measures to prevent further
contamination of the milk.

Scarlet fever. Knowledge of the details concerning the in-
fection of milk with scarlet fever is restricted some\vhat by
the fact that there is no general agreement as to the causative
agent of the disease. It is believed that the infectious material
resides in the throat, nasal secretions and skin (21). There
is, though, good epidemiological evidence that milk infection
with scarlet fever occurs frequently (32).

Milk-borne scarlet fever assumes a mild type (21). News-
holme (23) calls attention to the fact that " scarlet fever may
be caused by infected milk containing the contagium in such
an attenuated form or minute quantity that no symptoms
manifest themselves except as anomalous sore throat with
fever."

Investigation of the source of .milk supply responsible for
trouble, will reveal some rather close connection between a
case of the disease and the milk. It may be a case in the
house; bottles returned from a sick-room ; a convalescent, or
a nurse, or a patient's milking or handling milk.

The importance of milk as a carrier of scarlet fever is estab-
lished by convincing evidence. Harrington (13) has reported
a very extensive milk-borne scarlet fever epidemic that occurred
in Cambridge, Boston, and Summerville, Massachusetts. In
five days, 485 cases were reported among the customers of one
large dairy company. During a period of three weeks from
the beginning of the trouble, 717 cases were reported in the
district, of which 84 % were among the patrons of the dairy.
The source of infection was traced to a man employed by the
dairyman to taste milk, and who used the same spoon in sam-
pling each lot of milk. The daughter of this man was in the

G ASTRO- INTESTINAL INFECTIONS. 55

desquamating stage of scarlet fever, and he himself showed
markedly prominent papilla? of the tongue. Trask (32) has
collected information concerning 125 milk-borne scarlet fever
epidemics.

Castro-intestinal infections. The subject of clean milk in
its relation to health has been widely discussed in connection
with the subject of infant feeding. One-third to one-half of
all deaths under "one year are due to gastro-intestinal disorders.
The very heavy infant mortality from this class of diseases
has occasioned careful scrutiny into the causes contributing
thereto. It has been shown that 75% to 85% of those dying
from this cause are artificially fed. During the summer the
deaths from this cause rise, while those from other causes
remain stationary. In Paris, "the diarrheal death rate in
breast-fed infants, varies from a minimum of 2 per thousand
in winter to a maximum of but 20 per thousand during the hot
months ; the diarrheal deaths of the artificially fed, fluctuate
from a minimum of 12 per thousand in winter to a maximum
of 158 per thousand in the summer "(31). The striking differ-
ence here, leads to the suspicion that the food is to blame.

Evidence of the injury done by cow's milk in this connection
has not been completely worked out with reference to the spe-
cies concerned. Suspicion has been directed against the pep-
tonizing organisms, B. coli, B. proteus, streptococci, etc., or to
toxic products resulting from their growth.

Streptococci as a cause of gastro-intestinal disturbances have
been incriminated by agglutination experiments with the organ-
isms found in the feces. It has been found that the serum of
patients develops a specific agglutinating power for certain
strains' of streptococci found in the feces (6). Streptococci
are demonstrable in practically all raw market milk. The
difficulties of recognizing pathogenic streptococci in milk are
very great, because of the close resemblance of the common
lactic acid producing bacteria. Streptococcus infections of the
cow's uclder are very common and there is ample opportunity
for the infection of market milk (27). The subject is more
completely discussed in Chap. VII.

Evidence has been adduced from observation of the different

56 EPIDEMIC DISEASES TRANSMITTED BY MILK.

effects of clean and of highly polluted milk in infant feeding.
Clinical studies have shown that in hot weather children do
the best on good milk, and the worst on bad milk (26). The
marked decline in infant mortality in Xew York City, due for
the most part to the decline in mortality from summer diarrhea,
bears a close relation to the adoption of methods for rendering-
milk safe (9). Goler (ll) has shown the very striking effect
of reducing the bacterial content of a city milk supply, and
has shown a remarkable coincidence of simultaneous decline
of both bacterial count and infant death rate. The importance
of house infection in epidemic diarrhea, has been emphasized
by Newsholme (24) . He believes that the bulk of the infection
in epidemic diarrhea is derived in some way within the house,
and not derived from the farm. Sandilands holds similar
views (30). In proportion to the number of consumers, he
noted more diarrhea in infants fed on Nestle' s food containing
a few bacteria, than those on cow's milk with phenomenal
numbers of bacteria. He believes the disease to result from
food infection, generally from the excrement of a patient. He
emphasizes the importance of flies as agents in the transmission
of infection.

REFERENCES.

1. BIXM. Streptococcus diarrhea in San Francisco (streptococcus
gastro-enteritis). Pediatrics, Vol. XXI, No. 1, January, 1904.

2. BOWHII,!,. Milk, the vehicle of contagion in an outbreak of diph-
theria. Vet. Record \o. 567, April 8, 1899.

3. DKAX and TODD. Experiments on the relation of the cow to milk -
diphtheria. Jour. Hyg. (Cambridge), Vol. II, 1902, p. 194.

4. DKJ.KPIXE. Milk and other food poisoning and epidemic diarrhea.
Jour. Coinp. Path, and Ther., Vol. XVI, 1903, p. 77.

5. EAGER. Morbidity and mortality statistics as influenced by milk.
Bui. No. 41, Hyg. Lab., U. S. Pub. Health and' Mar. Hasp. Sen*.,
Washington, D. C., 1908, p. 229.

6. EDITORIAL. Streptococcus infection of the intestinal tract. Jour.
Amer. Mcd. Assoc., Vol. M, 1908, No. 15, p. 1236.

7. EYRK. The Bacillus diphtheriae in milk. Brit. Med. Jour. , Sept.
2, 1899.

REFERENCES. 57

8. FISH. Typhoid fever epidemic at Palo Alto, California. Published
by the Hoard of Health, Palo Alto.

9. FKKKMAX. The reduction in the infant mortality in the city of
New York and the agencies which have been instrumental in bringing
it about. Med. News, Sept. 5, 1903.

10. GKTTY. Infant mortality in the summer months, four. Amer.
Mcd. Assoc., Vol. 1^, 1908, No. 13, p. 1008.

11. GoivKR. Does the bacterial content of city milk influence the in-
fantile death rate? Archil'. Fed., September, 1906.

12. HARRINGTON. The problem of city milk supplies. Repts. and
Papers of the Amer. Pub. Health Assoc., Vol. XXXII, Part I, p. 153.

13. HARRINGTON. Milk as a carrier of infection. Ar. V. Med.Jour. ,
Vol. IvXXXV, 1907, p. 696.

14. HASKKUy. A typhoid fever epidemic from infected milk. four.
Amer. Med. Assoc., Vol. Iv, 1908, No. 11, p. 846.

15. HKMENWAY. The scarlet fever epidemic of 1907. Jour. Amer.
Med. Assoc., Vol. L, 1908, No. 14, p. 1115.

16. Hnjy. Time limit versus culture limit in diphtheria release.
Amer. Jour. Pub. Hyg., Vol. XVII, 1907, No. 4, p. 318.

17. KI.KIN. Pathogenic microbes in milk. Jour. Hyg. (Cambridge),
Vol. I, 1901, p. 78.

18. lyUMSDKN. The milk supply of cities in relation to the epidemi-
ology of typhoid fever. Bui. No. 41, Hyg. Lab., U. S. Pub. Health and
Mar. Hosp. Serv., Washington, D. C., 1908, p. 151.

19. MOORE. The control of diphtheria in small cities and country dis-
tricts from the bacteriological standpoint. N. V. State Med. Jour., Feb-
ruary, 1901.

20. MARSHAU,. Note on the occurrence of diphtheria bacilli in milk.
Jour. Hyg.( Cambridge), Vol. VII, 1907, p. 32.

21. McVAii,. The prevention of infectious diseases. I/ondon : Mac-
millan & Co., 1907.

22. NEUFEiyD. Typhus. Handbuch der pathogenen Microorganismen,
by W. Kolle and A. Wassermann, Bd. II, S. 303.

23. NEWSHOI,ME. An outbreak of sore throats and scarlet fever caused
by infected milk. Jour. Hyg. (Cambridge), Vol. II, 1902, p. 150.

24. NEWSHOI.ME. Domestic infection in relation to epidemic diar-
rhoea. Jour. Hyg. (Cambridge), Vol. VI, 1906, p. 139.

25. PARK. Typhoid bacilli carriers. Jour. Amer. Med. Assoc., Vol.
LI, 1908, No. 12, p. 981.

58 EPIDEMIC DISEASES TRANSMITTED BY MILK.

26. PARK and Hoi/r. Report upon the results with different kinds of
pure and impure milk in infant feeding in tenement houses and institu-
tions of New York City : a clinical and bacteriological stud}-. Archiv.
Fed., December, 1903.

27. REED and WARD. The significance of the presence of strepto-
cocci in market milk. Amer. Med., Vol. V, 1903, No. 7, p. 256.

28. ROSENAU, IvUMSDENand KASTI.E. Report on the origin and pre-
valence of typhoid fever in the District of Columbia. Bui. No. 35, Hyg.
Lab., r. S. Pub. Health and Mar. Hosp. Sen'., Washington, D. C., 1907.

29. ROSENAU, I^UMSDEN and KASTLE. Report No. 2 on the origin and
prevalence of typhoid fever in the District of Columbia. Bui. No. 44,
Hyg. Lab., U. S. Pub. Health and Mar. Hosp. Serv., Washington, D. C.,
1908.

30. SANDII^ANDS. Epidemic diarrhoea and the bacterial content of
food. Jour. Hyg. (Cambridge), Vol. VI, 1906, p. 77.

31. SCHERESCHEWSKY. Infant feeding. Bui. No. 41, Hyg. Lab.,
U. S. Pub. Health and Mar. Hosp. Serv. , Washington, D. C., 1908, p. 631.

32. TRASK. Milk as a cause of epidemics of typhoid fever, scarlet
fever and diphtheria. Bui. No. 41, Hyg. Lab., 'U. S. Pub. Health and
Mar. Hosp. Serv., Washington, I). C., 1908, p. 21.

33. TRASK. Milk in its relation to infectious diseases. Jour. Amer.
Med. Assoc., Vol. IvI, 1908, No. 18, p. 1491.

34. WARD. Notes on diphtheria. Monthly Bui. Cal. State Board of
Health, Vol. Ill, 1908, No. 10, p. 110.

35. WARD. Report of the department of hygiene. Twentieth Bien-
nial Report of the State Board of Health of California.

36. WARD and HENDERSON. The control of diphtheria in a public
school. Cal. State Jour. Med., August, 1907.

37. WESBROOK. Diphtheria infection in Minnesota. Jour. Amer.
Med. Assoc., March 25, 1905.

38. W HIPPIE. Typhoid fever, its causation, transmission and pre-
vention. New York : John Wiley & Sons, 1908.

39. WOODWARD. The municipal regulation of milk supply of the
District of Columbia. Bui. No. 41, Hyg'. Lab., f\ S. Pub. Health and
Mar. Hosp. Serv., Washington, D. C., 1908, p. 679. -

CHAPTER IV.

BOVINE TUBERCULOSIS AND OTHER CATTLE
DISEASES.

Bovine tuberculosis. (The subject of bovine tuberculosis and
its relations to the milk supply cannot be adequately discussed /2
without a consideration of the relations of the disease in its
purely economic aspects. )

Losses to the live stock industry. (The disease is a tremendous
source of loss to the live stock industry, and worse yet, the
majority of those men suffering the loss have not awakened to
the idea of the possibility of prevention. Precautions for the
control of tuberculosis have not yet been generally recognized
as a necessary detail in the management of the live stock or dairy
business. Losses are sustained by the decrease in production
from diseased animals by death, long before the expiration of
the natural life period, and by condemnation of carcasses in
the abattoir, in cases where an adequate meat inspection system
is maintained (17). These facts have been recognized by a
few, and the means of transmission have been determined, even
though the facts have not been acted upon in the United States
extensively enough to check the disease.}

Transmission by milk. ( Milk is one great factor in the spread
of tuberculosis among cattle. Slaughter-house statistics gath-
ered from observations on pregnant animals have demonstrated,
if such demonstrations were needed, that tuberculosis is very
rarely inherited. The common practice in raising dairy calves
has been for a long time to separate them from the cows early
and feed them on skim-milk. It is under these conditions that
an appalling amount of infection of calves occurs (37). The
recognition of this source of tuberculosis and its elimination
by heating the milk, has afforded the basis for the most prac-

60 BOVINE TUBERCULOSIS AND OTHER CATTLE DISEASES.

ticable scheme yet devised for the control of tuberculosis, —
the Bang method (21, 22, 23, 34, 35, 36, 38, 39, 54).

Infection of swine. (^But the tubercular cow is not merely a
menace to her young through the milk, but also casts a blight
upon the industry of pork production. The pig is particularly
susceptible to bovine tuberculosis. In districts where it is the
common practice to feed pigs on skim-milk and whey, the
results occasion the condemnation of such a high per cent, of
carcasses that buyers have learned to avoid certain districts on
this account. In any event, they pay a price for pork lowered
in anticipation of their losses from condemned carcasses or
parts.

Milk is not the only common means for the transmission of
tuberculosis by cattle.,, In the corn belt, pigs are raised in
association with beef cattle, so that they may utilize the feces
of cattle for feed. The magnitude of the losses occasioned in
this way has drawn attention to the matter of contamination
by feces as a source of the tubercle bacilli in milk (41, 42, 45).

Insidious onset. The insidious nature of the disease masks
its presence and wholly misleads the dairymen as to the
number of his cattle that are tubercular. A cow may be in
fine condition and apparently perfect health, and on slaughter
show the most serious advanced stage of involvement of the
internal organs. This is so common that the diagnosis by
physical examination by a veterinarian is entirely unsatisfactory.

Conditions governing prevalence . The prevalence of tubercu-
losis in herds seems to depend to a large extent upon the
number of opportunities that have been offered for the possible
introduction of infection. Small herds which have been built
up of calves raised on their mothers' milk, will be found in the
best condition (55). The large herds supplying city milk are
conducted upon a different plan, Dry cows are frequently
i»* sold, and their place taken by cows which have been bought
shortly before calving. Calves are butchered, for whole milk
is too precious to feed them and no skim-milk is available.
Under these conditions, there is every opportunity offered for
the introduction of tuberculosis. Among the dairies in which
calves are raised on skim-milk, a different source of infection

BOVINE TUBERCULOSIS. 61

is afforded. It is the practice for dairymen supplying cream-
eries to take back skim-milk to feed to the calves. This skim-
milk is mixed indiscriminately at the creamery, and thus a
ready means for the dissemination of the disease from herd to
herd is afforded. The heating of skim-milk, whey, etc., at
the factories, to kill the tubercle bacilli before distribution to
the dairymen for feeding purposes, is an important measure
for restricting the spread of the disease. It has been made
compulsory in some states.

Prevalence in herds. /It is rarely that figures on the number
of reacting animals in large herds supplying market milk are
available ; for the conditions are so bad that owners are cautious.
From reliable sources, the writer has learned of herds of one to
two hundred cows showing 90% reacting. Averages including
results from small herds are lower .J) /In New York State figures . .,
compiled from results of testing unuer the supervision of the
Commissioner of Agriculture, and from tests by private prac-
titioners, show 32% of the cows reacting. The disease was
found in 61% of the herds tested (22).) ^Recent tests of cows
supplying Washington, D. C., show 18.6% reacting.^) These
figures are lower than true conditions, for the cows tested
were either in herds where efforts to eradicate the disease
were in progress, or where the owner had no suspicion of ser-
ious trouble. The writer encountered practically the same
figures in Berkeley, Cal., among herds where the owners did
not refuse permission to test. Among 1022 cows in 22 herds
in California, Dr. Haring and the writer have found 31.9%
reacting. ( Eighty- two per cent, of the herds were found to
contain infected animals. ) The figures are compiled only from
results of whole herds, tested for the first time. Of 71 cows
pastured on vacant lots in Berkeley, only 8% reacted (55).
These figures concerning the prevalence of tuberculosis among
cattle in California were derived from results obtained largely
in herds in the San Francisco Bay region furnishing city milk
supply. It is not permissible to generalize from them regard-
ing the prevalence of the disease among cattle elsewhere, in
herds managed differently.

62 BOYIXE TrBERCTEOSIS AND OTHER CATTLE DISEASES.

Contamination of milk by tubercle bacilli. The channels by
which tubercle bacilli are eliminated from the body of the
tubercular cow, have been carefully studied. The elimination
of tubercle bacilli from the mouth, in the saliva, is not of direct
importance in the contamination of milk. When the uterus
is involved, or the urine contains tubercle bacilli, the proba-
bility of the infection of the milk is great. The tubercular
udder, whether diseased so badly as to permit detection or
so slightly as to escape detection by physical examination, gives
off tubercle bacilli. In this connection, the conclusions of
Mohler (19) bearing on the point at issue, are quoted :

"From the results of the experiments conducted in this Ia1x>ratory as
well as from the majority of similar investigations quoted in this article,
the following conclusions regarding the infectiousness of milk from tuber-
culous cows seem justifiable :

"1. The tubercle bacillus may be demonstrated in milk from tuber-
culous cows when the udders show no perceptible evidence of the disease.
either macroscopically or microscopically.

" 2. The bacillus of tuberculosis maybe excreted from such an udder
in sufficient numbers to produce infection in experimental animals both
by ingestion and inoculation.

"3. That in cows suffering from tuberculosis the udder may, there-
fore, become infected at any moment.-

' ' 4. The presence of the tubercle bacillus in the milk of tuberculous
COWTS is not constant, but varies from day to day.

" 5. Cows secreting virulent milk may be affected with tuberculosis to
a degree that can be detected only by the tuberculin test.

"6. The physical examination or general appearance of the cow can-
not foretell the infectiveness of the milk.

"7. The milk of all cows which have reacted to the tuberculin test
should be considered as suspicious, and should be subjected to steriliz-
ation before using.

"8. Still better, tuberculous cows should not be used for general dairv
purposes. ' '

I Ostertag (28) has reached contradictory conclusions, but in
view of all the facts available at present, the conditions encoun-
tered by him must be regarded as unusual. I /It has been shown
that an udder so slightly diseased as to Be detected only on
microscopic examination of the tissues, yielded tubercle bacilli
(29). The difficulty in determining exactly when an udder is

BOVINE TUBERCULOSIS. 63

tubercular complicates the matter of determining whether or
not tubercle bacilli are found in milk from a healthy udder.
In the light of facts recently brought to attention, the discus-
sion of this matter of the udder in its relations to milk inspec-
tion is not very profitable../

{ I The manure of cattle contaminated with tubercle bacilli is
regarded as an important source of tubercle bacilli in milk.
Reacting tuberculous dairy cows that retain the appearance of
health, may actively expel tubercle bacilli in the feces (41, 42,
43, 46). A very small percentage of such cases in a herd could
bring about a very extensive infection of the milk. Among
the possible sources of the bacilli, understood at present, are
sputum swallowed, and open tubercular lesions of the intes-
tines. Feces constitute the most common contamination of
milk as demonstrated by observation of dairy practice, and by
the microscopic examination of milk sediments. The presence
of tubercle bacilli in human feces in early cases has been noted

s^ and suggested as a means for the early diagnosis of the disease

Xsi).

r~~Tuberclc bacilli in market milk. Anderson (1) found in
/Washington, D. C., that 6.72% of 223 samples examined con-
I tained tubercle bacilli. The results analyzed according to the
source of the samples showed that about 11 $> of the dairies
whose milk was examined showed tubercle bacilli. His meth-
ods were such that he believes the results understate the true
conditions.

Schroeder (43) refers to the examination of 350 samples of
milk in Washington by different workers with the result that
about 5.5% showed tubercle bacilli. About one dealer out of
every ten was intermittently selling tuberculous milk. Hess
(9) examined 107 samples of milk in New York and found
tubercle bacilli in 16% of the samples. Trask (Ref. 33, Chap.
Ill) has collected the results of the work on tubercle bacilli in
done by a large number of investigators. ^

Human and bovine types of tubercle bacilli. .( The original
ideas of the complete unity of tuberculosis in cattle and in
man were based upon the identity of the lesions in gross and
microscopic appearance. TUp to 1896, the identity of the

64 BOVINE TUBERCULOSIS AND OTHER CATTLE DISEASES.

tubercle bacilli in the two branches of the disease was not
questioned. Then Theobald Smith pointed out certain differ-
ences in morphology, cultural characteristics and virulence
regarded as characteristic of the organism in man and bovines
(47, 48). That these differences are usually observed, is a
t that has received very, wide confirmation.

Views of Koch. In 1901 (13) and 1902 (14), Koch very
carefully reviewed the grounds for the belief that bovine tuber-
culosis is transmitted to man, and reached the conclusion that
it is not worth while to combat bovine tuberculosis in the
interest of the public health. Koch's paper raised an extraor-
dinary storm of protest, and likewise stimulated the study of
the problem along lines suggested by his arguments^ He
pointed out very clearly and conclusively the essential w
ness of the evidence frequently accepted as proof of the trans-
mission of tuberculosis to man. The very wide prevalence of
human tuberculosis makes it very difficult to establish the
absence of human infection in cases where cattle are suspected
as the source. He laid down certain conditions that must be
satisfied before transmission would be admitted as proven, and
these dicta are so stringent that it would be very difficult to
find any case conforming to them.

It has been observed by Koch that milk-borne tuberculosis
does not correspond to the other milk-borne diseases in the
matter of the sudden explosive occurrence of cases among
those consuming the milk. The known peculiarities of tuber-
culosis, such as its deliberate onset, and especially the concep-
tion of latency of infection -introduced by von Behring (52),
rather impair the value of the point as an argument against
the transmission of tuberculosis by milk.

Bovine tubercle bacilli in wan, Koch pointed out that the
recognition of bovine and human types of tubercle bacilli gave
a sound basis for determining the source of the disease in
human cases. It is along this line that the most conclusive
evidence of the transmission of the disease has been obtained.
The literature shows between forty and fifty cases in which
bovine tubercle bacilli have been isolated from infants and
children. This was conceded in 1907 by Theobald Smith (49),

BOVINB TUBERCULOSIS. 65

whose attitude is conservative and critical. In 1908 he stated :
" and it has been found that perhaps half of certain kinds of
tuberculosis in children, such as those of the glands of the
neck and abdomen, are due to infection from milk." (50)
/Insufficient work has been done to determine the percentage
of human tuberculosis caused by bovine tuberculosis. The Brit-
ish Royal Commission found the bovine type 14 times in 60
cases of human tuberculosis investigated by it (5). The sig-
nificant fact is that here is indisputable evidence to satisfy the
most conservative that tuberculosis is transmitted from cattle
to man.\

Intermediate types of tubercle bacilli. Some observers believe
that the study of a series of tubercle cultures reveals interme-
diate types varying from the extremes exhibited by human
and bovine cultures (3, 7, 20, 43). These intermediates have
been observed in both cattle and man. The observation has led
to the conclusion that certain characters of the tubercle organ-
isms are exceedingly variable. For instance, a bovine strain
in a child might after a time be modified by environment so
much as to disguise its original source. If this point of view
is taken, bacteriological distinctions — the only ones — between
tuberculosis in cattle and man break down, and the importance
conceded to bovine tuberculosis in connection with the public
ealth is consequently increased.

Channels of infection. Alimentary infection was formerly
thought to give rise necessarily to primary tuberculosis in the
mesenteric lymph nodes. The rare occurrence of this con-
dition was used by Koch as an argument to prove that tuber-
culosis in children does not frequently originate from milk.
Experimental work with reference to this point has shown that
the primary lesion in animals need not necessarily occur in a
mesenteric lymph node. Tubercle bacilli from the intestinal
tract may travel to the lungs via lymph node, thoracic duct
and blood, causing the primary lesion in the capillaries of the
lung or elsewhere (30). It is also believed that infection
may enter through the tonsils and cause tubercular involve-
ment of organs anterior to the diaphragm without ever travers-
ing the abdominal organs. There is a growing belief based on

66 BOVINE TUBERCULOSIS AND OTHER CATTLE DISEASES.

the work in meat inspection, that alimentary infection plays a
very important part in the infection of cattle and hogs. Such
observations have been made the basis of an assault on the
older theory of exclusive inhalation infection of the lung, and
tend to exalt the importance of alimentary infection.

International Congress of 1908. At the International Con-
gress on Tuberculosis at Washington in 1908, Koch stated
that he believed bovine tuberculosis to constitute a minor
source of tuberculosis in man. He regarded pulmonary tuber-
culosis (phthisis) as the cause of eleven-twelfths of the deaths
from tuberculosis and he was not convinced that the bovine type
of tubercle bacillus has been shown to produce that type of
tuberculosis in man. He disparaged the importance of the
cases in which the bovine type of bacilli have been found in
glands on the ground that glandular tuberculosis, in compari-
son with pulmonary tuberculosis, is a minor cause of fatality.
On the point concerning the frequency of primary abdominal
and cervical tuberculosis, the belief was held by many of the
delegates that these types of tuberculosis are much more fre-
quent and important than believed by Koch (6).

The portion of the resolutions of the Congress bearing on
bovine tuberculosis is as follows :

<i 3. * * Again, the utmost efforts should be continued in the struggle
linst tuberculosis to prevent conveyance from man of tuberculous in-
tion as the most important cause of the disease. Further, preventive
'measures must be continued against bovine tuberculosis, and the possi-
bility of the propagation of this to man should be recognized." (31)

Tuberculosis in Japan. The tendency to regard bovine tuber-
culosis as the chief source of tuberculosis in human beings, is
counteracted by certain evidence (1*2).

In Japan very little cow's milk is used for food, the average
amount consumed daily per capita being only 2.825 cc. Espe-
cially is it rarely employed as food for children. Human
tuberculosis is as frequent in Japan as in Europe and America.
There the disease in man dates back to the earliest chronicles.
Tuberculosis occurs only in foreign cows and their crosses with
native cattle. Pure native cattle are relativelv immune and

MEASURES AGAINST BOVINE TUBERCULOSIS. 67

no tuberculosis was known among Japanese cattle until the
introduction of foreign stock about thirty-five years ago.

Present status of controversy. That tuberculosis may be
transmitted from cattle to the human being, is an accepted fact
not even denied by Koch. The differences of opinion concern
the extent to which it occurs, and these in turn depend upon
the conception of the characters that may be accepted as defin-
ing an organism of bovine origin. On the whole, the belief is
that tuberculosis in cattle constitutes a minor source of tuber-
culosis in man.

Protection of the milk supply. The situation warrants the
enforcement of firm, effective measures for the protection of the
milk supply. The proven facts excite both disgust and appre-
hension on the part of the consumer. To correct such condi-
tions is a very legitimate function of food inspection service.
No question is raised as to the propriety of condemning car-
casses for generalized tuberculosis, even though most meat is
practically safe when cooked. The ground for condemnation
is the abhorrence and fear of consuming infectious tubercular
material. The same undesirable qualities are possessed by
milk of tubercular cows, only worse, for' it is not the practice
to cook milk.

Certain physicians show a tendency to avoid agitation con-
cerning cattle, the minor source of tuberculosis, for fear of dis-
tracting popular attention from the main source of infection- —
tubercular human beings. This, perhaps, is justifiable in so
far as the attitude relates to the spending of money. There is
no question but that money for fighting tuberculosis of man
could be more profitably spent than in attempts to eradicate
tuberculosis of cattle by slaughtering animals and indemnifying
the owners. This is an economic matter primarily.

Measures against bovine tuberculosis. A number of circum-
stances combine to make it most difficult to protect effectually
the milk supply from the germs of tuberculosis. ( The wide
prevalence of tuberculosis among cattle raises obstacles in the
way of expense incurred to the dairymen. A great many
attempts have been made to control the disease both in the
interest of the public health and as a purely economic measure.

68 BOVINE TUBERCULOSIS AND OTHER CATTLE DISEASES.

In most cases great expense has been incurred by the dairymen,
with little permanent benefit. Tuberculosis in general has
kept pace with the efforts directed against it, and in only a
few states can it be claimed that substantial progress is being
made in its eradication. Dairymen have, for almost a genera-
tion, been harassed by agitation over the subject and their atti-
tude towards public health measures is one of indifference or
open hostility. City milk supply is derived from such scattered
sources that effective administration is difficult. Then, too, the
individual co\vs comprising the herds are constantly changing
as they dry off and are replaced by fresh cows. Coupled with
this it should be noted that the majority of dairymen persist -
- ently ignore precautions against introducing the disease.\ Under
~ these conditions the temptation is great to resort to bribery in
some cases, or to legal measures for the purpose of invalidating
the ordinance. The 'Circumstances are such as to encourage
laxity in the enforcement of tuberculin test ordinances. A
sharp distinction should be drawn between the meanings of
the expressions ' ' in force ' ' and ' ' enforced ' ' as applied to an
ordinance.

Physical examination. While some advanced cases of tuber-
culosis can be recognized by physical examination, such an
examination will reveal but a small percentage of the cases
capable of disseminating infection.

The idea of inspecting dairy herds by physical examination
alone is based upon the belief that a physical examination is
capable of indicating the seriously diseased animals. The evi-
dence accumulated from post-mortem examinations of dairy
cattle, and from the bacteriological examination of feces, con-
troverts the truth of the assumption. If a physical examination
is to be of use, it must be so searching as to permit the detec-
tion of all those animals having open lesions in the respiratory
and alimentary tracts. Such results are not obtainable. Among
the dangerously tubercular animals may be found at post-
mortem examination the best looking cows in a herd. The
condition of flesh of an animal is worthless as a guide. The
good dairy cow certainly is emaciated at times, and this in
conjunction with an old coat of hair gives a miserable appear-

MEASURES AGAINST BOVINE TUBERCULOSIS. 69

ance. Under the circumstances, emaciation as a symptom of
tuberculosis cannot be given very heavy consideration. Aus-
cultation and percussion of the lungs do not yield the results
that might be expected, and the same may be said of palpa-
tion of the superficial lymph glands. Neither the lungs nor
accessible lymph glands are necessarily involved in advanced
cases.

Emphasis has been laid upon the value of detecting the
tubercular udder, as if it were a very important factor in the
contamination of milk. As a matter of fact, the development
of tuberculosis in the udder to a degree that would attract
attention is very rare. Smith (49) believes that roughly speak-
ing the udder becomes tuberculous through metastasis in per-
haps 1% of tubercular cows. Muller (27) states that 1.62%
of all cows slaughtered in Germany show tuberculosis of the
udder. Mammitis, associated with steptococci, is very com-
mon and causes indurated areas in the udder that raise insur-
mountable difficulties in the differential diagnosis by physical
signs. The bacteriological examination of samples of milk
from the suspected udder is the only reliable means for identi-
fying tuberculosis of the udder.

In the discussion of the tuberculosis problem the idea is
sometimes implied that the detection and removal of the worst
animals from a herd will effect some measure of improvement in
diminishing the disease. Such a procedure does not appreci-
ably diminish the opportunity for the further spread of infection
and certainly does not benefit the large number already slightly
affected. Physical examination and removal of the con-
demned animals anticipates by a considerable period the nat-
ural breaking down from the disease and results in the removal
of some others less seriously diseased but which happen to be
easily detected. It results in no permanent improvement along
the line of extinguishing the infection.

The writer's personal experience in physical examination of
dairy herds for tuberculosis has been most unsatisfactory.
About 300 cows supplying a town with milk were examined
once in each of two successive years. Cows showing definite
unmistakable physical signs of tuberculosis, warranting slaugh-

70 BOVINE TUBERCULOSIS AND OTHER CATTLE DISEASES.

ter, were not found, but three excited strong suspicion. The
dairymen either in accordance with regular practice or on
account of the moral effect of the inspection, had removed the
cows that persistently coughed. In the third year, the tuber-
culin test revealed the fact that 30% of the cows were tubercular.
During work in another town in a group of 64 tubercular cows,
only 9 showed physical signs of tuberculosis. The writer does
not feel that he is making a confession of discreditable incom-
petency, for his experience is not unusual. In one instance, a
recognized expert on bovine tuberculosis examined 378 reacting
cows and was able to recognize only 21 as tubercular by means
of physical examination.

The idea of the efficacy of physical examination to prevent
the presence of tubercle bacilli in milk persistently crops out
in the discussion of methods of milk inspection. As late as
May, 1907, a commission of physicians made the following
recommendations to the Mayor of New York (10):

' ' The Commission believes that the essential requirement is to secure
from the farm a safe, clean milk.

"Tuberculosis. — The risk of transmitting tuberculosis through milk
from cows to man is very slight, unless the disease in the cow is in an
advanced form or is present in the udder. Even this slight risk is con-
siderably lessened when such milk is mixed, as it generally is, with that
of healthy cows before it is sold. We believe that this danger has been
greatly overestimated in the public mind and that it can best be met by
systematic inspection and condemnation of cows revealing tuberculosis
on physical examination. Certain legislation regarding tuberculosis in
cattle now being contemplated at Albany has been carefully considered,
and the Commission believes that if suitable legislation can be secured
with adequate appropriations for the enforcement of the same, our milk
supply in this respect coming from the State of New York will be suit-
ably safeguarded. Such legislation should provide for notification of
city authorities of the existence of disease, which may be transmitted
through milk, occurring in the cows or in the families or the persons of
those handling milk."

"" Municipal activity on the tuberculosis problem will certainly
accomplish nothing worth \vhile if carried on along the lines
recommended above. The statements are apparently based on
the faulty assumption that a physical examination will reveal
cows affected wTith tuberculosis in an advanced form, and that

MEASURES AGAINST BOVINE TUBERCULOSIS. 71

such are the only ones disseminating large numbers of tubercle
bacilli. The idea is controverted by a mass of evidence too
weighty to be thus ignored. The Commission betrays a cer-
tain amount of hesitancy in regard to measures against bovine
tuberculosis, for elsewhere in the report the following recom-
mendation is made :

"Pasteurization. — Notwithstanding after all safeguards that may be
imposed by education and otherwise, there will be cases in which unsafe
milk will be produced or offered for sale, and all such milk must be
judged on its merits. The Commission, therefore, recommends that the
Board of Health should, according to circumstances, require efficient
sterilization or pasteurization of all milk which it finds unsafe for con-
sumption as raw milk, on account of a suspicion of the presence of tuber-
culosis or other disease in the cows or unsanitary conditions of the dairy
or a persistent high bacterial content. But in every instance milk so
heated should be rapidly cooled to -at least 40°P\, and be put after steril-
ization or pasteurization, into sterilized containers under aseptic precau-
tions. The pasteurization of milk should be done only a few hours
before delivery to the consumer, and the container should be marked
with the time and date of pasteurization and the degree and duration of
temperature employed for the purpose."

Tuberculin test. \ The tuberculin test is the only available
means for the detection of tuberculosis in cattle. ) fTurjerculin
is a sterile liquid product containing a concentrated extract
,a \ of tubercle bacilli. \~Trhe subcutaneous injection of a properly
^ standardized dose of tuberculin will induce a rise of tempera-
ture in a tubercular animal in which the disease isyactive, but
will have no effect upon a non-tubercular animal. ' The test is
indispensable in the control of the disease by revealing the ani-
mals in every stage of the disease beyond the incubation period.
/The test does not reveal the extent of the disease and hence is
of no value in discriminating between tubercular animals dis-
seminating infection and those not?\ The information obtained
furnishes the means of separating the healthy from the diseased.
In view of the fact that tuberculosis so frequently develops in
the animal rapidly, any tubercular animal in a herd is pot
tially if not actually dangerous. It is a most difficult matter
to convince the average man upon this point. The number o
animals reacting is oftentimes surprisingly large when the
general appearance of the herd is considered. Among those

72 BOVINE TUBERCULOSIS AND OTHER CATTLE DISEASES.

reacting there may be the finest appearing and best producing
cows in the herd. A post-mortem examination, revealing a
small lesion, does not convince the layman that the slaughter
was justified.

New tests for tuberculosis. Of late, considerable attention has
been paid to certain modifications of the method of applying the
tuberculin test (25). Among these are the intradermo (26)
and ophthalmo (56) tests. Their claim to attention is based
cmsj m p1 i ri ty-but they are as yet in the experimental stage.

Stable sanitation and tuberculosis. Good sanitary conditions,
good ventilation, reasonable exercise, good climate, good food
\ and general well being are in high repute as measures for
\ restricting and preventing tuberculosis in man. In some
V quarters there is a tendency to assume that the bovine, sur-
rounded by conditions that are by assumption rated as corres-
pondingly good, will be in a measure protected from bovine
tuberculosis. A true parallel does not exist, for the conditions
favoring the spread of bovine tuberculosis are such that the
best of stables in the best of climates or even no stable at all,
will not prevent the spread of the disease (54). Baker (4)
has produced some very striking evidence on the point drawn
from statistics concerning cattle slaughtered under Federal in-
spection in San Francisco.

Tuberculin test ordinances. The object of municipal legisla-
tion is not primarily the eradication of bovine tuberculosis, but
rather to ensure a pure milk supply. The legislation, there-
fore, need go no farther than to ensure the exclusion of milk
of diseased animals by requiring that all cows pass the tuber-
culin test and a physical examination. Since the milk supply
comes largely from without the borders of the city, it would
be difficult, both legally and practically, to go farther than this.
The dairyman is thus at liberty to accept the conditions im-
posed for a license by the city, or to sell his milk elsewhere.
The plan involves no compulsory interference with property
rights and does not necessarily contribute to the reduction of
bovine tuberculosis beyond the dairies immediately affected.

Tuberculin test ordinances are in force in a number of Amer-
ican cities. Probablv Minnesota heads the list of states in the

TUBERCULIN TEST ORDINANCES. 73

number of cities having the test. The list as given in the
Minnesota exhibit at the International Congress on Tubercu-
losis, Washington, 1908, is as follows: Minneapolis, St. Paul,
St. Cloud, Alexandria, Duluth, Mankato, Litchfield, Willmar,
Albert Lea and Winona. Montclair, N. J., is at present the
scene of a legal struggle between the dairymen and the Board
of Health, on the matter of the enforcement of a tuberculin
test ordinance. The Board of Health of Berkeley, Cal.,has
attempted to enforce two different tuberculin test ordinances
but has been enjoined by the courts from doing so in each case.

The complete, impartial enforcement of an ordinance pro-
hibiting the sale of milk from reacting cattle raises a host of
difficulties occasioned by the wide prevalence of tuberculosis.
The condemnation of, say, 25% of the cows supplying a city,
throws all the producers into the market for cows. Those for
sale are those .that have just reacted. During the excitement of
the enforcement of the tuberculin test ordinance, cow owners
will not sell cows subject to the test. Compliance with the
ordinance means reduction of the output of milk. Producers
will refuse to sell to the distributors in the city, and will market
the milk elsewhere. The dairies that at present are able to
comply with a tuberculin test ordinance, represent an insignifi-
cant per cent, of the milk supply of our larger cities.

Clean herds the goal. In isolated instances, the complete
enforcement of a tuberculin test ordinance is practicable, and
this should be the end towards which efforts everywhere should
be directed. The difficulties of the problem presented by the
larger cities must be met by a scheme that will permit gradual
improvement. Even with a bountiful supply of healthy cows
available, and with the cordial co-operation of the owners of
herds, the work of testing the herds and eradicating tubercu-
losis is a tremendous task and would take years. The con-
tinuance of present conditions must be discouraged, the public
health must be protected, and at the same time the measures
enforced must not disrupt the milk business.

The \Vashington plan. The most practicable scheme that
has been suggested is the compulsory pasteurization of all
milk produced from cows that have not passed the tuberculin

74 BOVINE TUBERCULOSIS AND OTHER CATTLE DISEASES.

test. The suggestion has been made by a Milk Conference
appointed by the Commissioners of the District of Columbia
(40). The members of the conference represented the various
Federal departments interested in the subject, together with the
dairymen. The conference recommends the classification of
milk into three grades, as follows :
Class 1 . Certified m ilk . ' '

This grade represents the highest class of milk, ordinarily
certified by medical societies. The tuberculin test and a bac-
terial count of under 10,000 per cc., are among the require-
ments. (See Chap. IX.)

' ' Class 2. Inspected milk. ' '

This is a lower grade of milk, produced from tested cows,
and differing from the former, chiefly, in that the conditions
under which the milk is produced need not be equal to those
of dairies in Class 1. The bacterial count shall not be more
than 100,000 per cc.

" Class 3. Pasteurized milk. Milk from dairies not able to comply
with the requirements specified for the prochiction of milk of classes 1
and 2 is to be pasteurized before being sold, and must be sold under the
designation 'pasteurized milk1. Milk for pasteurization shall be kept at
all times at a temperature not exceeding 60°F. while in transit from the
dairy farm to the pasteurization plant, and milk after pasteurization shall
be placed in sterilized retainers and delivered to the consumer at a tem-
perature not exceeding 50°F. All milk of an unknowrn origin shall be
placed in class 3 and subjected to clarification and pasteurization. No
cow in any way unfit for the production of milk for use by man, as deter-
mined upon physical examination by an authorized veterinarian, and no
cow suffering from a communicable disease, except as specified below,
shall be permitted to remain on an}- dairy farm on wThich milk of class 3
is produced, except that cows \vhich upon physical examination do not
show physical signs of tuberculosis may be included in dairy herds sup-
plying milk of this class, although they may have reacted to the tuber-
culin test.

' ' This milk is to be clarified and pasteurized at central pasteurization
plants, which shall be under the personal supervision of an officer or
officers of the health department. These pasteurization plants may be
provided either by private enterprise or by the District Government, and
shall be located within the city of Washington."

Elsewhere in the report, the conference makes the following
recommendations regarding tuberculosis :

TUBERCULIN TEST ORDINANCES. 75

' ' Identification of dairy cattle. That all cows on dairy farms produc-
ing milk for the District of Columbia be tagged, tattooed, or otherwise
marked for purposes of identification.

' ' Tuberculin testing or pasteurization required. That all milk pro-
duced for use in the District of Columbia shall either come from cattle-
free from tuberculosis as shown by the tuberculin test, which tuberculin
test shall be repeated at least once every year, or be subjected to pas-
teurization under the supervision of the health department in case the
herd is not tuberculin tested.

' ' New dairy cattle to be tuberculin tested. That hereafter no addition
.shall be made to any herd producing milk for use in the District of Col-
umbia, whether such herd has or has not been tuberculin tested, unless
the cattle so added have been tested with tuberculin and found to be free
from tuberculosis.

" Neiu licentiates to have herds tuberculin tested. That hereafter no
license shall be granted to produce milk for use in the District of Col-
umbia unless the herd by which such milk is to be produced has been
found by the tuberculin test to be free from tuberculosis."

The compulsory pasteurization of all the milk supply of a
city will be attended with difficulties, but these are slight as
compared with those associated with the enforcement of a
tuberculin test ordinance. Chicago has adopted the scheme
of enforcing the tuberculin test, with the alternative of pas-
teurizing the milk.

Test by city official. The testing of cattle is best carried on
by a veterinarian employed by the municipality. It is highly
desirable that he be paid well enough to warrant devoting his
time exclusively to the work in hand. The requirements of
the work, even in a small city, call for the undivided attention
of one man for milk inspection and tuberculin testing. vThere
should be a decided increase in the budget allotments of munic-
ipalities for the proper enforcement of tuberculin test ordi-
nances, f The important requirement is that the inspector
should noYbe engaged in private practice and consequently
dependent upon the good will of the dairymen. The customary
system of paying a moderate salary for a portion of the time-
of a practicing veterinarian is detrimental to efficient work for
the municipality. If the application of the tuberculin test is
made optional with the veterinarian, the test will certainly not
be made. The veterinarian can not do his full duty without

76 BOVINE TUBERCULOSIS AND OTHER CATTLE DISEASES.

giving offense that will eventually destroy his practice. Private
practice and efficient municipal work are incompatible.

The man carrying on the testing must be proof against the
corruption to which he will be continually exposed. His pro-
fessional skill and judgment will be criticized by the dairy-
men and by jealous unprofessional aspirants for his ' 'job. ' ' The
officials or board to whom he is responsible must entertain
unswerving faith in his qualifications, else they will waver in
the face of the storm of protest and denunciation that will
emanate from the dairymen.

Test by any licensed veterinarian. In some of the larger
municipalities the ordinance may require the dairyman to pro-
duce a report from any qualified veterinarian, but such a pro-
vision is an invitation to fraud and dishonesty. Under such
conditions the effectiveness of a tuberculin test ordinance is
likely to be entirely destroyed.

In Berkeley, Cal., an ordinance was passed (Appendix A)
permitting any licensed veterinarian to make tuberculin tests,
but containing provision for subsequent tests by the repre-
sentative of the health officer in case the latter doubted the
accuracy of the reports. That this feature was undesirable
was fully recognized but it would have been quite out of the
question to have obtained the appointment of a city veteri-
narian to do all the work. The first attempt to exercise the
provision in regard to retesting resulted in litigation and the
invalidation of the ordinance on a legal technicality not con-
cerning the test.

The Chicago tuberculin test ordinance is weak on this point,
for in the rules regarding the tuberculin testing of cows any
licensed graduate veterinarian is permitted to do the work
(Appendix B). The Duluth ordinance is stronger in this fea-
ture (Appendix C).

Milk contracts. In the larger cities most of the retailers
are supplied by the producers or others, under the terms of
yearly contracts. Unless the health regulations have been very
rigidly enforced, these contracts are not liable to contain
clauses providing that the milk conform to health require-
ments. Any radical or sudden change in the law is apt to

APPLICATION OF THE TUBERCULIN TEST. 77

make trouble between the retailer and the producer. Due
warning obviates the difficulty.

Application of the tuberculin test. In the earlier days when
the tuberculin test was in the experimental stage, it was cus-
tomary to take a series of normal temperatures of the cows
during the whole day preceding the injection of tuberculin.
The data thus obtained permitted the plotting of temperatures,
before and after injection, in a most convincing way. The con-
finement of the cows for the day for taking these temperatures
interferes greatly with the secretion of milk and entails much
extra work. These circumstances furnish a strong incentive
for decreasing the number of these " normal " temperatures.
In practice, veterinarians take about two temperatures before
injecting, merely to establish the fact that the animal is not in
a febrile condition.

Temporary numbers. The identification of the cows during
the test is satisfactorily accomplished by painting numbers on
the rump with green paint. The numbers will, in a few cases,
be smudged before drying and the difficulty from this may be
obviated by numbering all the cows in duplicate.

Facilitating observations of temperatures. The observation
of temperatures may be expedited by the use of several ther-
mometers simultaneously. When more than one thermometer
is used the risk of breakage necessitates attaching the ther-
mometer to the cow by a string. Special ring top veterinary
thermometers on the market facilitate tying a string to the
thermometer. NThe human clinical thermometer may have a
string attached to it through the medium of a rubber band
firmly wrapped around the top. There is attached to the other
end of a six-inch string a pair of dog-tooth clasps. When the
thermometer is inserted in the rectum, the clasp is attached
either to a firm concretion of manure on the hair or to the
skin, which latter however is liable to cause kicking.

Nervous cows will greatly delay the work by resisting the in-
sertion of the thermometer. This may be obviated by enlisting
the services of one of the milkers to stand at one side and pat the
cow on the back. Quiet, businesslike work, with the minimum
of delay and excitement of the cow, must always be kept in mind.

78 BOVINE TUBERCULOSIS AND OTHER CATTLE DISEASES.

The services of at least one non-professional assistant, besides
the stable-man, will be found very useful. He could be
employed to insert thermometers and to record the tempera-
tures on the blank provided for the purpose. The responsible
work of reading the thermometers can thus becarried on
rapidly by the veterinarian making the test. V^FTg. 10 shows a

Herd of.. L^t**,

Location

(J

Injected . ^.PA

Test by fa ft J{

• Temperatures Q ^

. After Yf /HV •

A3

A3

1.2

1.1

1. 1

1,2

2.1

a*

6,4

0

S

/*V«". /*v. Blank for recording temperatures.

convenient blank for recording temperatures. It will be noted
that the temperatures are written in an abbreviated form. For
instance 101.6° is recorded as 1.6, etc. The blank as used is
three inches broad and about seven inches long. The width
permits folding the records and filing them away with the
identification cards mentioned on page 81. The significance of
the numbers in the column at the extreme right is described
^n page 82.

After the temperature is read, the thermometer is inserted in
a pot of vaseline until needed for use next time. If there is
no convenient ledge at the rear of the cows, a light portable
box, about a yard high, forms a convenient stand for the vas-
eline and thermometers.

APPLICATION OF THE TUBERCULIN TEST. 79

Injection with tuberculin. The tuberculin is injected during
the evening at a time to allow an interval of ten hours before
the cows are milked the next morning. The insertion of the
hypodermic needle is accomplished with greatest facility and
least danger to the operator by leaning on the withers of the
cow and injecting upon the side opposite to the operator.
Asepsis is practically accomplished by dipping the needle in
concentrated carbolic acid each time before use.

Temperatures after injection. Temperatures are taken every
two hours from the 10th to the 16th hours, and later in the
case of those animals showing an elevation to 103.5° at the
16th hour. It is frequently recommended that the tempera-
tures be taken from the 8th to the 20th hour. Such require-
ments impose serious h'ardship on the dairyman by the loss of
milk, due to the annoyance of the cows. For all practical
purposes the shorter period of taking temperatures is sufficient
to reveal a reaction. The animals should be under as quiet
and natural conditions as possible during the test. It is usually
desirable to allow them liberty, with access to drinking water,
between the 12th and 14th hours.

Interpretation of temperatures. A rise of 1.5°F. above the
normal, if gradual and distributed over a period of several
hours, followed by a gradual decrease, constitutes a reaction.
Fig. 10 shows two typical tuberculin reactions. A brief
upward fluctuation of the temperature is not regarded as sig-
nificant. In the case of the ordinary well marked reactions,
it is not considered necessary to continue taking temperatures
after the fastigium has been passed. Animals exhibiting ques-
tionable reactions should be retested one month later, injected
with three times the usual dose of tuberculin.

It is the rule not to condemn animals showing a rise of tem-
perature when in oestrum or when within six weeks of par-
turition. It is well to inject all such animals in a herd and to
retest later those exhibiting a fever.

Limitations of tuberculin test. The tuberculin test does not
reveal facts concerning the extent of disease. Hence in a small
percentage of reacting cases no lesions can be found in post-
mortem, probably due to the fact that the lesion is too small

80 BOVINE TUBERCULOSIS AND OTHER CATTLE DISEASES.

to detect. Animals in the advanced stages sometimes fail to
react but the existence of tuberculosis in such cases should be
readily detected from the physical appearance of the animal.
There are at least two conditions under which an animal once
failing to react may at a later time react to the test. During
the incubation period of the disease, that is, when the tubercle
bacilli are within the body but before a lesion is developed, no
reaction will occur. Later, the animal will respond. Thor-
oughly encapsulated lesions will not permit response to tuber-
culin, but later may become active and cause reaction. These
facts are of great significance in pointing to the necessity of
frequent testing.

Fraud. Dishonesty on the part of the attendants of the
cattle may be responsible for erroneous results of a test. It is
an important fact that a tubercular animal will not give two
reactions in succession. Thus a dairyman may inject his herd
a few days previous to an unwelcome expected test, and there-
by wholly mislead the man making the later test. Tuberculin
is readily purchased upon the market but its sale should be
subject to restrictions. Febrifuge drugs are said to be also
used to defeat the tuberculin test, by counteracting the febrile
conditions. Frauds may be extensively practiced, but unex-
pected tests will eventually expose the dishonest practice.

fmanent identification of animals. The thorough identifi-
cation' of the animals is under most conditions a necessary

matter. The liability of fraud
is very great when any com-
pulsion attends the application
of the test or the subsequent
disposition of the reacting ani-
mals. A useful means of iden-
tification is afforded by metal
ear-tags, numbered serially
and bearing a legend identify-
ing the official body respon-
sible for the test, as for in-
stance, a 'board of health or
a milk commission. Fig. 11

Fig. 11.
cattle.

Ear-tag Jor

APPLICATION OF THE TUBERCULIN TEST.

81

shows ear-tags as described. The characters borne by the tag
are .stamped on at the factory and consequently may not be
readily imitated for fraudulent purposes. Furthermore, dupli-
cation of numbers will not occur. The ear-tags should be
affixed after a test to all animals whether they have reacted
or not. It is of no particular value to tag only non-reactors,
since after subsequent exposure of the animal to infection the
tag gives no guarantee of freedom from tuberculosis. In one
case where such a practice was in vogue, it was observed that
dairymen would willingly purchase a tagged cow without fur-
ther guarantee of health. Furthermore, owners have pointed
out the death from tuberculosis of a tagged animal as an evi-
dence of the unreliability of the test. It is not well to encour-
age the idea that an ear-tag is a fetish against tubercular infec-
tion. It is quite possible that ear-tags may be lost and also
that ear-tags may be transferred to other animals for fraudulent
purposes. An absolutely safe identification, then, requires fur-
ther safeguards. For this purpose the writer devised a 3 by
5-inch card printed with the outline of a cow and blanks for
important data (53).

Label No.

Breed

Own*

Test No.

Fig. 12. Card employed by the writer for the identification of cows.

82 BOVINE TUBERCULOSIS AND OTHER CATTLE DISEASES.

Fig. 12 shows such a card filled out with descriptive matter,
etc. The amount of sketching required is very small. The
color of the animal, together with some distinctive peculiarity,
may be all that is necessary to record for purposes of identifi-
cation. Mutilations of the ears or the character and location
of brands may be readily indicated by a stroke of the pencil.
The insertion of the temporary and permanent numbers on
both the card and the temperature blank makes it possible to
keep an accurate record of the test history of every cow in a
herd. Such cards are carefully filed for use in subsequent
inspection of the herd. For instance, when rules or ordi-
nances require the testing of all animals admitted to a herd,
the identification system gives the inspector full knowledge of
the facts. The presence of a condemned animal, minus the
ear-tag, could be proven by comparison of the markings of the
cow with the sketches. Moak has devised a .slight modification
of the identification card as shown in Fig. 13. He is enabled
to file away the tuberculin test record on the card, which is
a feature particularly useful when a few cows are tested at a
time.

Disposal of tubercular animals. In some states it may be
possible for dairymen to take advantage of partial indemnifica-
tion offered by the state to the owners of condemned animals.
n the early days of effort to exterminate bovine tuberculosis,

any states adopted a policy of at least partially indemnifying
the owner for losses sustained in destroying animals. This
method in general failed to accomplish permanent benefit,
because sufficient funds were not appropriated to make the
work as thorough as the circumstances demanded. The right
of an owner of a tubercular animal to demand indemnification
for the loss occasioned by its slaughter on the ground of the
benefit to the public health, seems to be an open question.
The principle certainly is not recognized when carcasses are
condemned in abattoirs nor is a man in quarantine for the pub-
lic good compensated therefor. The owner of a herd, in tol-
erating the existence of the disease, is quite as responsible for
the losses from it as is the public. The practice of indemnifica-
tion certainly facilitates work in combating tuberculosis.

•n O 2

•n o 2

2 O

7> >

-22 3

O

•n o 2

-no 2

BOVINE TUBERCULOSIS AND OTHER CATTLE DISEASES.

fit is the purpose here merely to allude to the matter of
control of bovine tuberculosis. ' When municipalities interfere
with dairymen in the tuberculosis matter, the cry is usually
raised that nothing should be done until indemnification is
available. Under the conditions ordinarily imposed by a city
ordinance, such a claim is absurd.

\ The slaughter-house always offers an opportunity for the dis-
posal of tubercular animals. The regulations of the Bureau
of Animal Industry of the United States Department of Agri-
culture permit the veterinary inspectors to pass certain slightly
*-) diseased carcasses as fit for human food. In most of our abat-
toirs there is no inspection of meat by Federal or local author-
ities, consequently we consume regularly the flesh of broken-
down tubercular dairy cows. In view of this, the slaughter of
slightly diseased cows that have merely reacted to the test,
cannot be regarded as especially disgusting. The slaughter of
reacting cows does not afford a great loss to the dairyman, for
at certain seasons of the year there is not a wide margin of
difference between the beef and the dairy value of a scrub cow.
k--ft""iSDy no means a simple matter to enforce the clauses of
ah ordinance requiring that reacting animals be permanently
removed from the herd. Unfortunately it is quite necessary
to assume that condemned cows may be returned to the herd
by stealth. Thorough inspections, with the aid of the identifi-
cation system, will quite prevent the general practice of such
fraud. An instance has come to notice where the owner was so
deaf to warning and so blind to the truth regarding the trans-
missibility of tuberculosis that he kept the reacting cows to
suckle^dalry calves.

{stances ari.se in which the dairyman, having dried off a
number of reacting cows, keeps them at pasture a year and
submits them for a retest later. In general such animals will
continue to react from year to year, although some may cease
to react because of the encasulation of the lesions. Such
animals unless very closely supervised, are not desirable in a
herd free from tuberculosis. There is, furthermore, the great
probability that the owner will tamper with the reacting cows
by surreptitiously injecting them with tuberculin with the

^

EDUCATION OF DAIRYMEN. 85

purpose of deceiving the veterinarian testing them in good
faith. The rule, "once condemned, always condemned," is

. safest to follow.

Disinfection. The disinfection of a stable after the reacting
v __ animals have been removed is a matter that most vitally con-
cerns the dairyman and he might be expected to do this work.
In practice, though, it will be found that the dairyman will
not do the work thoroughly or may neglect it entirely. It is
much better that it be done under the supervision of the veter-
inarian making the test.

A thorough cleaning of the stable is a prerequisite to the use
^of the disinfectant and should be carried out with such
thoroughness that no manure remains anywhere. Mercuric
chloride is a good disinfectant for use in the stable. It is made
up in the proportion of 1 ounce to 8 gallons of water and
should be mixed in a wooden tub or barrel. The mercuric
chloride is best brought into solution in a small quantity of
hot water and then diluted with the whole amount of cold

" water.

On account of the danger of defacing metal work about the
mangers by the action of the mercury, it may be well to use
some other disinfectant there. A 5% solution of carbolic acid
or of formalin may be used (8).

Education of dairymen concerning bovine tuberculosis. The
regulations against bovine tuberculosis in the interest of the
public health and without the alternative of pasteurization must
eventually result in either driving the dairymen into completely
subjugating the disease in their herds, or in the abandonment
of the ordinance. Ignorance or skepticism or false economy
will induce quite a percentage of dairymen to violate the prin-
ciples necessary for the control of bovine tuberculosis, in spite
of a tuberculin test ordinance. The business can not stand
such a drain, and rigid enforcement inevitably results in driving
the unfit out of business. The intermittent way in which
tuberculin test ordinances have been enforced always lends
hope that interference will be but temporary. The ultimate
triumph of a tuberculin test ordinance is impossible unless the
dairymen are educated and converted on the subject of bovine

86 BOVINE TUBERCULOSIS AND OTHER CATTLE DISEASES.

tuberculosis. To this end, the dairymen supplying a city

should all be supplied with circulars of information dealing

with the problem of the control of bovine tuberculosis. In a

large number of states, assistance in preparing such circulars

may be had from state veterinary sanitary officials, veterinarians

^^agricultural experiment stations, and also from the Bureau

~4> of Animal Industry at Washington.

Anthrax. This cattle disease is certainly transmissible to
man by inoculation, but the writer has not encountered a report
of a case where the infection has been borne by milk.

The disease appears among cattle during warm weather in
certain localities. Its onset is so abrupt and death usually
occurs with such suddenness that there is little likelihood of a
diseased animal's transmitting the disease through the milk.
During an outbreak of anthrax it might be enough from the
public health standpoint to insist that no cows with a fever be
allowed in the dairy. Even such a requirement would ordin-
arily be superfluous, for a cow with a high fever due to anthrax
would not yield milk.

Suppuration. Marked examples of suppuration warrant the
temporary rejection of the milk of a cow. Dehorning, or the
accidental loss of a horn, is quite apt to lead to infection of
the frontal sinuses, and if the discharge is not properly re-
moved it creates a disgusting stench. For this reason dehorn-
ing is preferably done \vhen a cow is dry. Open suppurating
actinomycotic lesions are objectionable. Small abscesses occur
on the backs of cows, due to the presence of larvae, Hypodenua
bovis, or H. lineaia, popularly called warbles. Trouble is best
prevented by squeezing out the larvae when small. Suppur-
ation about the udder is especially objectionable. Mammitis
(garget) furnishes good reason for excluding the milk of the
cow from sale, even if only one quarter of the udder is involved.
Since garget is caused by streptococci, all sorts of streptococcus
infections in man have been attributed to the use of milk con-
taining streptococci. Such transmission of infection is possible
and probable, but difficult to prove. The subject is further
discussed in Chap. VII.

MALTA FEVER. 87

Cowpox. This eruptive disorder of the skin of the udder is
very common and terminates in ulcers and frequently in ab-
scesses. At times it would be a very serious matter to demand
the rejection of the milk of all cows showing small areas of
infection. The very common practice of using carbolized
vaseline on the lesions practically prevents danger of trans-
mitting infection from these areas when not on the teats.
Regulations on the subject might well allow the use of milk
when the udder only is involved and under treatment, and
exclude cases showing open abscesses or involvement of the
teat. The writer is not familiar with reports of cases where
the transmission of this disease through the milk has been
proven. The fact that vaccination against smallpox is largely
practiced has been noted in connection with the subject.

Parturition disturbances. There is a general consensus of
opinion that the milk of a cow for about a week after calving
(colostrum) has an unusual composition and is unwholesome
for human consumption. ' The Federal standard sets this period
at ten days, and likewise prohibits the use of milk for fifteen
days before calving (Chap. X). Besides, during this time
the udder is more or less inflamed in consequence of the resump-
tion of function. Cases exhibiting retained placenta, metritis,
etc., should not be allowed in the milking herd.

Malta fever. This disease, prevalent on the island of Malta
and elsewhere, chiefly in the Mediterranean region, is caused
by Micrococcus melitensis. Lately it has been determined by a
commission appointed to investigate the disease that it is prim-
arily one of goats and is transmitted through the milk. M.
melitensis may be found in the milk of apparently healthy goats.
The blood serum of such animals gives a positive agglutination
reaction with M. melitensis, and that of other goats not contain-
ing the germs does not. The test has led to the conclusion
that 41% of the goats in Malta are infected. Ten per cent, of
them have the germs in the milk. In 1905 a very conclusive
demonstration of the relation of goats to the disease was
afforded by the shipment of a number of goats from Malta to
the United States. The milk was used by the crew of the ship
with the result that a number of men contracted Malta fever.
The imported animals were slaughtered (2).

88 BOVINE TUBERCULOSIS AND OTHER CATTLE DISEASES.

Foot and mouth disease. This highly contagious disease of
cattle is transmissible to man through the milk (24). The
symptoms in cattle consist of eruption of vesicles in the mouth,
around the coronet, between the toes and on the udder, accom-
panied by a rise of temperature. The mortality is not high,
but great losses are incurred by the diminution of the milk flow
due to the fever and to the starvation caused by the mouth
lesions. Mycotic stomatitis, which occurs occasionally on the
Pacific coast and elsewhere, is liable to be confused with foot
and mouth disease (18). This last mentioned disease is com-
mon in Europe but is not permanently implanted in the United
States. It has been introduced several times and successfully
eradicated. At the time of writing, the existence of the dis-
ease has been discovered in certain areas of Pennsylvania, Mich-
igan and New York.

Milk-sickness. In the early days of the settlement of the
central portion of the United States, cases of illness attributed
to consuming milk of diseased cattle were not uncommon (16).
The symptoms in cattle and in man are quite definite. Fifty
years ago the disease had a distinct standing in medicine but
of late years it has been all but forgotten, due to its present
rarity. Jordan and Harris (ll) have recently discovered a
focus of infection in the valley of the Pecos River, N. M.,
which gave them opportunity to study cases in both cattle and
man. In man the symptoms, among others, included vomiting,
constipation, and great prostration. They noted the sweetish
odor of the breath described in the old literature. Affected
cattle in the early stages appeared weak and exhibited a shuf-
fling gait, accelerated breathing, and sometimes trembled and
fell. In advanced stages the animal lay with the head to one
side as in milk fever, but continued to tremble. Post-mortem
examination with bacteriological examination did not result in
the identification of any of the well-known cattle diseases. An
organism called by them B. lactinwrbi was regarded as the
cause of the disease.

REFERENCES. 89

1. ANDERSON. The frequency of tubercle bacilli in the market milk
of the city of Washing-ton, D. C. Bui. No. 41, Hyg. Lab., U. S. Pub.
Health and Mar. Hosp. Serv., Washington, D. C., 1908, p. 163.

2. ANDERSON. The relation of goat's milk to the spread of Malta
fever. Bui. No. 41, Hyg. Lab., U. S. Pub. Health and Mar. Hosp.
Serv., Washington, D. C., 1908, p, 195.

3. ARISING. Variations of the tubercle bacillus especially from the
standpoint of virulence. Trans. Sixth Intern. Cong, on Tuberculosis,
Washington, D. C., 1908.

4. BAKKR. Tuberculosis in range cattle in California. Trans. Sixth
Intern. Cong, on Tuberculosis, Washington, D. C., 1908.

5. BRITISH ROYAL COMMISSION ON HUMAN AND ANIMAL TUBERCU-
LOSIS. Second interim report. Jour. Comp. Path, and B act., Vol. XX,
1907, p. 81. (See Ref. 33.)

6. Conference in camera on human and bovine tuberculosis. Jour.
Amer. Med. Assoc., Vol. U, 1908, No. 15, p. 1262.

7. FiBiGER. Investigations into the relations of human and bovine
tuberculosis and tubercle bacilli. Trans. Sixth Intern. Cong, on Tuber-
culosis, Washington, D. C., 1908.

8. HARING. The disinfection of stables. Cir. No. 19, Agr. Exp.
Sta. Univ. of Cal., Berkeley, Cal., 1908.

9. HESS. A study of tuberculous contamination of New York City
milk. Trans. Sixth Intern. Cong, on Tuberculosis, Washington, D. C.,
1908.

10. HOLT, JACOBI, BRYANT, PRUDDEN and FREEMAN. Report on
the milk supply of New York City, with recommendations. Arch. Ped.,
February, 1908.

11. JORDAN and HARRIS. The cause of milksickness or trembles.
Jour. Amer. Med. Assoc., Vol. L/, 1908, No. 21, p. 1665.

12. KITASATO. The behavior of native Japanese cattle with regard
to tuberculosis. Congress of Arts and Science, Universal Exposition,
St. Louis, 1904, Vol. VI, p. 137.

13. KOCH. The combating of tuberculosis in the light of the experi-
ence that has" been gained in the successful combating of other infectious
diseases. Jour. Comp. Path, and Ther., Vol. XIV, 1901, p. 203.

14. KOCH. The transmissibility of bovine tuberculosis to man. Jour.
Comp.J\ith. and Ther., Vol., XV, 1902, p. 287.

15. KOCH. The relation of human and bovine tuberculosis. Trans.
Sixth Intern. Cong, on Tuberculosis, Washington, D. C., 1908; Jour.
Amer. Med. Assoc., Vol. 1,1, 1908, No. 15, p. 1256.

16. McCoY. Milk sickness. Bui. No. 41, Hyg. Lab., U. S. Pub.
Health and Mar. Hosp. Serv., Washington, D. C., 1908, p. 211.

90 BOVINE TUBERCULOSIS AND OTHER CATTLE DISEASES.

17. MELVIX. The economic importance of tuberculosis of food-pro-
ducing animals. Tratis. Si.vth Intern. Cong, on Tuberculosis, Wash-
ington, D. C., 1908.

18. MOHLKR. Mycotic stomatitis in cattle. Cir. No. 51, Bur. Aniui.
Ind., r. S. Dept. Agr., Washington, D. C., 1904.

19. MOHLER. Infectiveness of milk of cows which have reacted to
the tuberculin test. Bui. Xo.44, Bur. Anim. Ind., (\ S. Dept. Agr.,
Washington, D. C., 1903.

20. MOHLER and WASH BURN. A comparative study of tubercle ba-
cilli from varied sources. Bui. Xo. 96, Bur. Anim. Ind., I'. S. Dept.
Agr., Washington, D. C., 1907.

21. MOORK. Bovine tuberculosis. Bui. No. 250, Cornell l~niv. Agr.
E.rp. Sta., Ithaca, N. Y., 1908.

22. MOORE. The dissemination and control of tuberculosis as illus-
trated in the bovine species. Proceedings of the Seventh Annual Con-
ference of Sanitary Officers, New York State Department of Health, 1907.

23. MOORE. Can tuberculosis be eliminated from cattle? .Y. Y. State
Jour, oj Med., Vol. VIII, May, 1908, No. 5, p. 249.

24. MOORE. The pathology of infectious diseases of animals. Ithaca,
N. Y.: Taylor & Carpenter, 1908.

25. MOORE. Tuberculin and its use in the control of bovine tubercu-
losis. Cir. No. 1, X. )'. State Vet. Col., Ithaca, N. Y., 1908.

26. Moussu. The intradermo-reaction to tuberculin in animals.
Trans. Sixth Intern. Cong, on Tuberculosis, Washington, D. C., 1908.

27. MiJLLER. Milk and dairy products as sources of infection in tuber-
culosis. Jour. Com. Path, and T/ier., Vol. XIX, 1906, p. 19.

28. OSTERTAG. Untersuchung iiber den Tuberkelbazillengehalt der
Milch von Kiihen, welche lediglich auf Tuberkulin reagiert haben,
klinische Ersheinungen der Tuberkulose aber nicht zeigen. Zeitschr.
Fleisch. u. Milchhyg., Bd. IX, No. 12, S. 221.

29. RABINOWITSCH und KEMPNER. Beitrag zur Frage der Infecti-
ositat der Milch tuberculoser Kiihe, sowie iiber den Nutzen der Tuber-
culinimpfung. Zeitschr. Hyg. u. Infectionskrank., Bd. XXXI, 1899, S. 137.

30. RAVENEL. The passage of tubercle bacilli through the normal
intestinal wall. Jour. Med. Research, X. S., Vol. V, 1903-4, p. 460.

31. Report of Committee on Resolutions. Jour. Amer. Med. Assoc.,
Vol. U. 1908, No. 15, p. 1260.

32. REYNOLDS and BEEBE. Dissemination of tuberculosis by the
manure of infected cattle. Bui. No. J03 , l^niv. of Minn. Agr. E.vp.
Sta., St. Anthony Park, Minn., 1907.

33. ROYAL COMMISSION, appointed to inquire into the relations of
human and animal tuberculosis. Second interim report. Part I, Re-

REFER KNCKS. 91

port; Part II, Appendix. Vol. I, The pathogenic effects of bovine vi-
ruses, by Dr. A. Stanley Griffith. Vol. II, pp. 1-616, Vol. II, pp. 617-
1217, The pathogenic effects of human viruses, by Dr. Iv. Cobbett. Vol.
Ill, Additional investigations of bovine and human viruses, by Dr. L/.
Cobbett, Dr. A. Stanley Griffith and Dr. F. Griffith. Vol. IV, Compar-
ative histologies? and bacteriological investigations, by Arthur Kastwood,
M. I).

34. RrssEU,. The history of a tuberculous herd of cows. Bui. No.
78, ('nil', of Wis. Agr. E.vp. Sta., Madison, Wis., 1899.

35. RussEiyi,. A lesson in bovine tuberculosis. Bui. ATo. 114, Univ.
of Wis. Agr'. E.vp. Sta., Madison, Wis., 1904.

36. RUSSEU,. Two ways of treating tuberculosis in herds. Bui. No.

126, Univ. of Wis. Agr. E.rp. Sta., Madison, Wis., 1905.

37. RUSSEIJ,. The spread of tuberculosis through factory skim milk,
with suggestions as to its control. Bui. No. 143, Univ. of Wis. Agr.
l<;.\-p. S/tr., Madison, Wis., 1907.

38. SALMON. The tuberculin test for tuberculosis. Cir. No. 79, Bur.
Anim. Ind., U. S. Dept. Agr., Washington, D. C., 1905.

39. SALMON and SMITH. Tuberculosis of cattle. Cir. No. 70, Bur.
Anim. Ind., ir. S. Dept. Agr., Washington, D. C., 1904.

40. Sanitary milk production. Cir. No. 114, Bur. Anim. Ind., U.
S. Dept. Agr., Washington, D. C., 1907.

41. SCHROEDER. The occurrence and significance of tubercle bacilli
in the feces of cattle. Trans. Si.rth Intern. Cong, on Tuberculosis,
Washington, D. C., 1908.

42. SCHROKDER. The unsuspected but dangerously tuberculous cow.
Cir. No. 118, Bur. Anim. Ind., U. S. Dept. Agr., Washington, D. C.,
1907.

43. SCHROEDER. Tuberculous infection through milk. Pediatrics,
Vol. XX, No. 7, p. 422.

44. SCHROEDER and COTTON, Experiments with milk artificially in-
fected with tubercle bacilli. Bui. No. 86, Bur. Anim. Ind., U. S. Dept.
Agr., Washington, D. C., 1906.

45. SCHROEDER and COTTON. Tubercle bacilli in butter. Cir. No.

127, Bur. Anim. Ind., U. S. Dept. Agr.. Washington, D. C., 1908.

46. SCHROEDER and MOHI^ER. The tuberculin test of hogs and some
methods of their'infection with tuberculosis. Bui. No. 88, Bur. Anim.
Ind., f\ S. Dept. Agr., Washington, D. C., 1906.

. 47. SMITH. A comparative study of bovine tubercle bacilli and of
human bacilli from sputum. Jour. E.rper. Med., Vol. Ill, 1898, Nos.
4 and 5.

48. SMITH. Studies in mammalian tubercle bacilli (III). Jour. Med.
Research, N: S., Vol. VIII, 1905, p. 253.

92 BOVINE TUBERCULOSIS AND OTHER ANIMAL DISEASES.

49. SMITH. The channels of infection in tuberculosis, together with
some remarks on the outlook for a specific therapy. Trans. Mass. Med.
Soc. for 1907.

50. SMITH. The bovine and the human type. Jour. Amer. Med.
Assoc., Vol. U, 1908, No. 15, p. 1258. (A journal abstract.)

51. Sous-CoHEN. Bacteriological examination of the feces as a means
of early diagnosis in tuberculosis. 'Transactions Third Annual Meeting
of the National Association for the Study and Prevention of Tubercu-
losis, p. 228.

52. VON BEHRING. The suppression of tuberculosis, etc. New York :
J. Wiley & Sons.

53. WARD. The identification of cows. The Cornell Countryman,
Vol. Ill, 1906, No. 5, p. 110.

54. WARD and HARING. Bovine tuberculosis. Bui. No. 199, Univ.
of Cal, Agr. Exp. Sta., Berkeley, Cal., 1908.

55. WARD and HARING. The prevalence of tuberculosis among dairy
cattle in the vicinity of San Francisco', California. Trans. Sixth Intern.
Cong, on Tuberculosis, Washington, D. C., 1908.

56. WHITE and McCAMPBELL. The ophthalmo-tuberculin test in
cattle. Trans. Sixth Intern. Cong, on Tuberculosis, Washington, 1908.

CHAPTER V.

MUNICIPAL SANITARY CONTROL OF MILK.

Control of milk supply. The dairy business is generally
regulated by a licensing system. Municipal ordinances define
the qualities required in the milk sold, and specify certain
methods that shall or shall not be practiced in its production.
The issuing of a license to sell the milk may be made condi-
tional upon the compliance with certain demands. The desired
standard may be maintained by a system of frequent renewal
of license, by provisions for the revocation of license, or' by the
exaction of other penalties through the courts.

Inspection. Knowledge of the requirements of municipal
milk inspection and of methods of accomplishing desired results
has been increasing very rapidly of late. A particularly care-
ful and exhaustive study of present conditions and remedial
measures has recently been made in Washington by a Confer-
ence appointed by the Commissioners of the District of Col-
umbia (3). The report of that conference with accompanying
papers is a valuable guide for shaping new legislation on milk
sanitation. The organization, administrative methods and
legal features of municipal milk inspection in Washington
have been described by Woodward (18-).

The inspection of equipment of the establishments and the
methods of handling milk constitutes an important part of any
municipal milk inspection service. In actual practice, the
inspector will fall far short of accomplishing the best results
unless he becomes an instructor in dairy practice, as well as
an agent to detect violations of law. He must point out on
the spot defects and ways of improvement, which, if not carried
out, may be made occasion for prosecution. He must also
furnish a comprehensive report to his superior officer in regard
to existing conditions.

94 MUNICIPAL SANITARY CONTROL OK MILK.

The dairy score card. The dairy score card has been found
a most useful means for simplifying the work of dairy inspec-
tion. The system is adapted from a method used to score the
conformation of cows, etc. All of the essential facts of im-
portance regarding equipment and methods are tabulated in an
orderly manner, and numerical weight is assigned to each point
in proportion to its importance. The inspector takes up each
point in detail and enters on the score card a number express-
ing his opinion of the relation that the condition in question
bears to the standard of perfection. The total score represents
his very carefully analyzed opinion of the condition of the
dairy as compared with the standard of perfection followed.

The score card has many advantages. The tendency to
neglect details in the inspection is checked, for the inspector
has before him comprehensive suggestions. If he is inexper-
ienced, any tendency to overestimate or underestimate the
importance of various details is obviated. In making recom-
mendations regarding certain details his advice is made more
weighty by the score card, to which he may refer the dairyman.
A copy of the score, left with the dairyman, is a permanent
record of the criticisms, as is likewise the copy kept by the
inspector. By comparison of the scores made at different
times the progress of improvement maybe measured.

Inspection with scoring can most readily bring about the
proper equipment of dairies in the matter of buildings and
equipment, such as cooling and scalding apparatus, etc. These
features are necessary and desirable, but beyond them is the
problem of ensuring the practice of a uniformly thorough asep-
tic technic. During the visits of the inspector some idea of
the technic may be obtained by observation. The necessity
for haste to accomplish results in some cases prevents the in-
spector from personally observing the practice of all the details
of milk handling. Experience in observation, supplemented
by cross-questioning, enables him to draw out information on
matters that he may not have time to wait to see. In any
event, there are long periods between visits when the methods
are not under control. The magnitude of dairy inspection
makes it difficult to have these visits frequent enough. New

INSPECTION. 95

York City has 30 inspectors to look after thirty or forty thous-
and dairies and follow the product to the consumer. Only 15
of these men work outside of the city (4). Washington is
more fortunate with 960 dairies for 6 inspectors (18). These
men visit on an average 2.8 dairies per day.

The situation in these cities suggests a doubt as to whether
inspection work of our larger cities can be expanded sufficiently
to bring about a reform in the methods of farm laborers ignor-
ant of aseptic technic.

The following score card is one adopted by the Official Dairy
Instructors' Association, at the meeting in July, 1908. This
latest modification represents the consensus of opinion of the
body of men most competent to judge such matters, including
in its membership those who have been most active in the
introduction of the score card and most experienced in its use.

UNITED STATKvS DEPARTMENT OF AGRICULTURE,

BUREAU OF ANIMAI, INDUSTRY,
DAIRY DIVISION,

SANITARY INSPECTION OF DAIRIES.

DAIRY SCORE CARD.

Adopted by the Official Dairy Instructors' Association.
(.Subject to revision at future meeting's.)

Owner or lessee of farm

P. O. Address ... State

Total number of cows Number milking.

Gallons of milk produced daily

Product is retailed by producer in :

Sold at wholesale to

For milk supply of

Permit No Date of inspection , 190.

REMARKS ...

(Signed)..... '.

Inspector.

OF

UNIVERSITY

Of

£''-UK>RNl£,

[Reverse. ~\

DETAILED SCORE.

EQUIPMENT.

vSCORE.

SCORE.

Per-
fect.

Al-
lowed

METHODS.

Per-
fect.

Al-
lowed

cows.
Health

6

COWS AND STABLES.

Cleanliness of cows
Cleanliness of stables
Floor 2
Walls 1
Ceiling and ledges ]
Mangers and partitions 1
Windows 1

8
6

6
2

2

8
9

1

• 2

3

2

5

3
3

l

Apparently in good health 1
If tested with tuberculin once
a year and no tuberculosis is
found, or if tested once in
six months and all reacting
animals removed 5
(If tested only once a year and
reacting animals found and re-
moved, 2.)
Comfort
Bedding 1
Temperature of stable 1
Food
Water
Clean 1

2

2
2

4
3

3

2
4

1
1

3
1
1

1

2
2

Stable air

Barnyard clean and well drained .
Removal of manure daily to field
or proper pit
(To 50 feet from stable, 1.)

UTENSILS AND MILKING.

Care and cleanliness of utensils ....
Thoroughly cleansed 5
Inverted in pure air 3
Cleanliness of milking
Clean, dry hands 3

Fresh. 1
Light: Foursq. ft. of glass per cow
(3sq. ft.,3; 2 sq. ft., 2; 1 sq. ft.,1.
Deduct for uneven distribution.)
Ventilation : Automatic system
(Adjustable windows, 1.)
Cubic feet of space for cow: 500
to 1000 feet
(Less than 500 feet, 2 ; less than
400 feet, 1 ; less than 300 feet, 0.)

STABLES.

Location of stable

Udders washed and dried 6
(Udders cleaned with moist cloth,
4 ; cleaned with dry cloth at least
15 minutes before milking, 1.)

HANDLING THE MILK.

Cleanliness of attendants
Milk removed immediately from
stable
Cleanliness of milk room
Prompt cooling. (Cooled imme-
diately after milking each cow)
Efficient cooling ; below 50° F
(51° to 55°, 4 : 56° to 60°, 2.)
Storage; below 50° F....
(51° to 55°, 2; 56° to 60°, 1.)
Transportation ; iced...
(For jacket or wet blanket al-
ow 2 ; dry blanket or covered
wagon, 1.)

Total

Well drained. 1
Free from contaminating sur-
roundings 1
Construction of stable
Tight, sound floor and proper
gutter 2
Smooth, tight walls and ceiling 1
Proper stall, tie, and manger. 1

UTENSILS.

Construction of utensils

Water for cleaning
(Clean, convenient, abundant.)
Small-top milking pail
Facilities for hot water or steam...
Milk cooler .-.
Clean milking suits

HANDLING THE MILK.

Location of milk room
Free from contaminating sur-
roundings 1
Convenient _v 1
Construction of milk room
Floor, walls, and ceiling 1
Light, ventilation, screens 1
Total ...

40

60

Score for equipment -+- Score for methods.

. =: Final Score.

NOTE 1. — If any filthy condition is found, particularly dirty utensils, the total score shall be
limited to 49.

NOTE 2.— If the water is exposed to dangerous contamination or there is evidence of the pres-
ence of a dangerous disease in animals or attendants, the score shall be 0.

INSPECTION. 97

The score card eliminates the wide variations of individual
judgment in criticising dairy conditions. There .still remains
room for variations between the work of different inspectors.
It would hardly be fair to compare a group of dairies on the
basis of the work of .several inspectors. Professor R. A. Pearson
has introduced a scheme to eliminate the effect of variations in
individual judgment. The inspectors are furnished a list of
questions, the answers to which will bring out the actual con-
dition of the dairy. The answers made by the inspector are
placed in the hands of an expert who, in his office, compiles
the facts in the form of a score. Thus the work of a number
of inspectors may be unified by one mind and the quality of
uniformity imparted to the work of all. The system is being
used with satisfaction by the Boards of Health of Ithaca, N. Y.,
Geneva, N. Y., and elsewhere. l*he blanks used are repro-
duced below. The description of what constitutes perfection
under each heading is a commendable feature.

DEPARTMENT OF DAIRY INDUSTRY, NEW YORK STATE COLLEGE OK
AGRICULTURE.

MILK INSPECTION.

Dairyman ..... Date..

P. (). Location...

No. Cows milking In herd Ots. Milk Cans or Bottles....

Milk sold to License No

Report by At milking time? Hour M.

I. Health of the herd and its protection.
Do all cows appear healthy?....

Are udders sound and free from signs of disease?

Are cows tuberculin tested?

Date of last test... . Bv whom..

Is the stable well built to protect from the weather ?

Are cows brought in during bad storms?

How many hours are the cows out daily?. .
Width of stall .... . Length. .

98 MUNICIPAL SANITARY CONTROL OF MILK.

Is the stall comfortable? How are the cows tied?

Kind and quality of bedding

Where are cows kept when sick and at calving time?

Is the stable well located?

Number and size of windows

Size of the stable, length width height

How ventilated? ...

Kinds of feeds used

Are they of good quality and proportions?....
Source of water for cows
Method of watering

II. Cleanliness of the con's and their surrounding's.

Are the cows clean ? How are they cleaned?

Is the hair clipped about the udder?

Is the udder cleaned before milking? How? When?

Is the stable free from accumulation of cobwebs, dirt and dust?

Is the stable white-washed?

Kinds and number of other animals, if anv, in same room with cows

Same, adjacent rooms What openings between?

Is the stable protected from such sources of contamination as privy,

etc. ?

How often is the manure removed from the stable?

Is the barnyard free from manure pile? And mud holes?

Is the pasture clean and free from injurious plants? And mud

holes?.. .

Is the stable provided with dust-tight ceiling? And partitions?

Is feeding done before or after milking?

Is the floor swept or dampened before milking?

Is the air free from dust and odors?

III. Construction and care of the utensils.

Are all utensils such that they can be thoroughly cleaned?

Method of washing utensils?

How are the utensils sterilized? ...

INSPECTION. 99

Is the water used for washing utensils pure? .. How do you

know?....

What is its source?

Is the source protected against contamination?

How are utensils cared for after cleaning?

Is a small-top pail used for milking? If so, what style and

si/.e of opening?

IV. Health of employees and manner of milking.

What evidence is there of absence of contagious disease and of ex-
posure of family and employees to disease?

Are the milkers clean personally?

Do the milkers wear clean over-all suits? How often are

the over-alls washed?

Do the milkers wash their hands just before milking?

Where?
Do milkers have wet hands when milking? ,....

Are milkers careful not to dislodge hair and dirt from the cow while

milking ?

Is the foremilk discarded?

V. Handling the milk.

How is the milk cooled?

How soon after milking is the milk cooled?

To what temperature?

Is the milk handled in a room detached from the stable?

What kind of floor?

Is the milk room used exclusively for milk, and is it free from dirt

and odors?

At what temperature is the milk kept after cooling?

How is milk cared for during transportation to market?

DEPARTMENT OF DAIRY INDUSTRY, COLLEGE OF AGRICULTURE.
CORNELL UNIVERSITY.

Score Card for Production of Sanitary Milk.

Date

Dairv of

P. O.

PER-
FECT.

SCORE.

Remarks

.
Health of the
herd and
its protec-

Health and comfort of the cows and
their isolation when sick or at
calving- time
Location, lighting and ventilation of
the stable
Food and water

45

35
20

Total

100

II.

Cleanliness
of the cows
and their
surround-

Cows
Stable
Barnyard and pasture
Stable air (freedom from dust and
odors)

30
20
20

3d

ings.

Total

100

III.

Construction of utensils and their
cleaning- and sterilizing

40

Construction
and care of
the uten-

Water supply for cleaning and loca-
tion and protection of its source.:.
Care of utensils after cleaning
Use of small-top milking pail

25
20
15

SllS.

Total

100

Health of employees

45

IV.

Health of em-

Clean over-all milking suits and milk-
ing with clean, drv hands

30

ployees and
manner of
milking

Uuiet milking, attention to cleanli-
ness of the udder and discarding
foremilk..

25

Total

100

Prompt and efficient cooling

35

V.

Handling

Handling milk in a sanitary room
and holding it at a low tempera-
ture

35

the milk.

Protection during transportation to'
market

30

Total....

100

TOTAL OF ALL SCORES

500

If the total of all scores is And each division is The sanitary conditions are

480 or above 90 or above EXCELLENT

450 or above SO or above GOOD

400 or above 60 or above MEDIUM

Below 400 .... Or any division is below 60.... ....POOR

The sanitary conditions are Scored by

INSPECTION. 101

\ Reverse J\

A BRIKF DKSCRIPTION OF WHAT CONSTITUTES PRRFRCT UNDER EACH

HEADING.

I. Health. No evidence of chronic or infectious disease or of acute
disease in any member of the herd on the dairy premises. Free-
dom from tuberculosis proven by the tuberculin te.st made within
one year.

Comfort. Protection from weather extremes. Stall comfortable, —
at least 3 feet wide for a small cow, or 3^ feet for a large cow ;
length of stall sufficient for cow to rest easily. Sufficient bedding.
Frequent out-door exercise.

Isolation. Removal of cows to comfortable quarters outside of the
dairy stable, when sick or at calving time.

Location of Stable. Elevated, with healthful surroundings.

Lighting. As light as a wrell lighted living room, and with not less
than four square feet for light from the east, south or west, for
each cow.

Ventilation. An adequate ventilating system of the King or other
approved pattern, and, except when the stable is being cleaned,
no marked stable odor.

Food. Clean, wholesome feeding stuffs, fed in proper quantities.

Water. Clean, fresh water, free from possibility of contamination
by disease germs.

I.I. Cows. Cleaned by thorough brushing, and where necessary by
washing; no dust nor dirt on the hair (stains not considered).
The udder thoroughly cleaned by brushing at least thirty minutes
before milking, and by washing just before milking, leaving the
udder damp to cause dust to adhere.

Stable. Free from accumulation of dust and dirt except fresh ma-
nure in the gutter. Apart from horses, pigs, privy, poultry -
house, etc. »

Barnyard and Pasture. No injurious plants, no mudhole nor pile
of manure or any decaying substance where cows have access.

Stable Air. Free from floating dust and odors. Tight partition or
floor between the space occupied by cows and that used for storage
of feed or other purpose.

III. Construction of Utensils. Non-absorbent material and every part
accessible to the brush, and, except inside of tubes, visible when
being cleaned.

102 MUNICIPAL SANITARY CONTROL OF MILK.

Cleaning. Thorough cleaning with brush and hot water, and rins-
ing. No laundry soap. Thorough sterilization.

// 'ater, from a source known to be pure ; protected from contamin-
ation from seepage, or surface drainage.

Care of ( 'tensils. vSuch as to avoid contamination by dust as w7ell
as coarser dirt.

Small-top /W/,-«-with opening not over seven inches in diameter,
and at lea.st one-third of this opening protected by hood.

IV. Employees, — free from contagious disease and not dwelling in or

frequenting any place where contagious disease exists.

Milking Suits, — freshly laundered and clean ; ample to protect from
dust and dirt from the milker's person or clothing.

Milker1 s Hands. Hands and teats dry when milking. Hands thor-
oughly cleaned before milking each cow.

Milking Quietly,— so as to avoid dislodging dirt from cow's hair.
At least four streams of foremilk from each teat to be discarded
into a separate vessel.

V. Cooling. Cooled within fifteen minutes of milking, to temperature

below 45 degrees F.

Handling, — in a room used exclusively for handling milk, and free
from dust, dirt and odors ; and the milk after being cooled, always
at a temperature below 45 degrees.

Protection during transportation. Protected from dirt by tightly
• closed receptacles, temperature always below 45 degrees F. ; not
delayed in transit, reaching market within twenty-six hours after
milking.

Through the efforts of the Dairy Division, Bureau of Ani-
mal Industry, U.S. Department of Agriculture, the score card
is being widely used by municipalities. On June 30th, 1908,
the score-card system of inspection had been adopted in 60
cities of the United States, located in 25 states, and in one
Canadian city. A score card for use in California should be
slightly modified to meet local conditions. On account of the
milder climate, cows are not confined in the stable so long and
ventilating systems, etc., are of less importance. The score
card need not necessarily be recognized in legislation, for the
publication by the board of health of .the scores of the dairies

INSPECTION.

103

furnishes an incentive for improvement. An example of legal
recognition of the score card is as follows :

" STANDARD BASKD ON SCORE 'CARD. No milk shall hereafter be sold
or offered for sale or exchange in the city of New Brunswick which shall
be produced in dairies having a rating below 60 per cent, as based on the
score card adopted by the Board of Health, City of New Brunswick, State
of New Jersey."

Improvement in Richmond, \*a. The score card has been
found a useful means for recording the improvements in the
equipment and methods of milk production. The results ob-
tained by Levy (12) in Richmond, Virginia, are most striking.
The inauguration of a system of dairy inspection in which the
score card was used gave opportunity for recording the change
in dairy conditions from month to month. The results are
given in tabular form below.

TABLE IV.

THE PERCENTAGE OF DAIRY FARMS IN VARIOUS CLASSES DUR-
ING THE FIRST TWELVE MONTHS OF DAIRY
INSPECTION IN RICHMOND, VA.

May /, 1907, to May /, 1908.

ClyASS.

Scoring below 30

Scoring between 30 and 40

Scoring between 40 and 50

Scoring between 50 and 60

Scoring between 60 and 70

Scoring between 70 and 80

Scoring between 80 and 90 ....

Average of all scores for month.

PERCENTAGE OF ALL DAIRIES INSPECTED FOR
THE MONTH WHICH FELL IN EACH CLASS.

1907

1908

I

I

1

bj

I

"o

p

\

9

1

1

"|

13.8

26.5

3.9

4.0

30.8

42.9

21.0

10.7

26.2

22.4

38.2

29.4

40.0

23.7

14.8

15.8

2.8

13.8

8.2

22.4

33.3

45.0

35.6

45.9

36.8

11.3

13.6

6.8

5.7

10.8

13.2

22.6

12.5

33.9

29.5

23.6

35.2

44.1

39.8

34.3

4.6

1.3

3.5

6.8

8.2

18.4

31.0

25.4

34.2

42.9

1.6

5.4

19.7

16.9

19.2

17.1

41.5

36.4

47.5

50.5

51.4

57.0

58.4 60.5

70.4 69.6

71.5

72.0

The results are shown in graphic form in Fig. 14.

104

MUNICIPAL SANITARY CONTROL OF MILK.

Fig. 14. Diagram shouting improvement in dairv scores
mond, \ra.

Washington milk supply. Webster (17) has reported the
scores of the dairies supplying Washington as shown in the
following table :

TABLE V.
SCORES OF DAIRIES SUPPLYING WASHINGTON.

Scoring from

Virginia.

Maryland.

District of Columbia.

.Number.

% of all.

Number.

% of all.

Number.

% of all.

0 to 10 ...

'

A

10 to 20

4

76

^f

20 to 30 .....

7

2.18

76

14.44

2

3.02

30 to 40 ...

44

14.96

173

32.85

7

10.60

40 to 50 ...

83

28.23

164

31.18

13

19.69

50 to 60

89

30.20

74

14.01

21

31.81

60 to 70 ..',

53

18.02

22

4.18

13

19.69

70 to 80

14

4.42

10

1.90

9

13.63

80 to 90 ...

3

1.02

3

.55

1

1.51

90 to 100 ...

1

.34

activities. The Dairy Division of the Bureau of
Animal Industry has further encouraged education as a factor

INSPECTION. 105

in the improvement of the milk supply. In co-operation with
the Cleveland (Ohio) Chamber of Commerce, a city milk and
cream contest was held (ll). The entries in all classes were
judged with the assistance of score cards, A satisfactory
number of entries was made, and the interest in results con-
stituted a potent educational factor.

Important features in dairy practice may be emphasized by
the use of posters printed on muslin, like that in Appendix E.

Inspection of cows. The examination of the cows should in-
clude a manipulation of the udder in each case, for by this
means only can udder disease be detected. In suspicious
cases, a little milk should be drawn from each teat. Among
the conditions revealed may be acute mammitis, various skin
eruptions, external abscesses of the udder or teats, etc. Vary-
ing degrees of induration due to mammitis are not uncommon.
A very marked hardening of one or more quarters may be due
to tuberculosis, but the correctness of the suspicion is best
verified by a bacteriological "examination of the discharge, if
any is obtainable. Other objectionable conditions are more
easily recognized, such as the various inflammatory conditions
which, when neglected, give rise to offensive odors. It is the
general practice to keep such minor cases in the regular milk-
ing herd, and to neglect rather than treat the conditions. A
much more satisfactory arrangement would be afforded by
arranging a hospital, where all cows with disgusting affections
could be milked and treated.

Inspection of dairy apparatus. Excellence of technic is of
fundamental importance in milk production, and the condition
of utensils, is an excellent index of the standard prevailing in
the dairy. The sources of contamination, with reference to
utensils and methods of avoiding them are discussed in Chap-
ters I and IX. There are certain pieces of dairy apparatus
that invite neglect in cleaning and merit particular attention.
Milk pumps, milking machines, bottling machines, rubber
pipe, faucets, metal pipes with elbows, rusty pails, strainers
(both metal and cloth) all are danger points with reference
to the contamination of milk.

In the care of milk utensils is to be found the one great uni-

106 MUNICIPAL SANITARY CONTROL OF MILK.

versal fault of ordinary dairymen ; namely, that the heating of
utensils after washing is not thoroughly done.

Inspection of water supply. The source of the water supply
with reference to possible contamination by the germs of
typhoid fever is of great importance. There are many ways
in which contaminated water may become a source of danger
to milk. Deliberate watering of milk, accidental watering
through leaks in apparatus, or rinsing apparatus in cold water,
are some of the more common channels of contamination.

If the supply is from a shallow dug well, its relation to the
privy or area where chamber slops are thrown out deserves
careful attention. The possibility of contamination by under-
ground drainage depends upon the character of the soil, the
slope of the land and the distance. It certainly is not asking
too much that the privy be at least 100 feet from the well un-
der any condition. The protection of the well from surface
drainage is important. Chickens will visit the privy vault if
they have opportunity, and then may go to the puddle of water
around the well for a drink.

Driven wells offer similar dangers of contamination from
holes in casings, but in general furnish a more reliable source
of water. Springs and streams offer obvious possibilities for
contamination. Bolton (l, 2) has very thoroughly discussed
the subject of water supply for dairies and the bacteriological
examination of the same.

Scope of inspection. .Every stage in the progress of milk from
the dairy to the consumer offers conditions necessitating sani-
tary supervision. Attention should be paid to milk at the
farm, during transportation to shipping point, at shipping
point, during railroad transportation, at the railroad station,
at the city dairy depot, on city wagons and in the retail store.
It is well to go even farther and instruct the consumer about
the care of milk. Methods of transportation attract particular
attention in relation to speed and means employed for refriger-
ation. The distributing milk depot offers opportunity for
re-infection from utensils or attendants.

Tlie score card for city milk plants. The inspection of city
milk plants is likewise facilitated by the use of the score card.

V. S. DEPARTMENT OF AGRICULTURE, BrRKA.r OF ANIMAL INDUSTRY,
DAIRY DIVISION.

SANITARY INSPECTION OF CITY MILK PLANTS.

Owner or Manager.. Trade name

City Street and No State

Number of wagons Gallons sold daily \ rveam

Peimit or license No Date of inspection 190

SCORE.

REMARKS.

Perfect.

Allowed.

MILK ROOM.

Location

Construction —
Floor 3 |
\Vallsand ceiling 3 >
Drainage... 4J
Cleanliness
Light and ventilation
Equipment —
Arrangement 3 }
Con str uct io n —
Sanitary 2 1
Durability 2
Condition 3
Cleanliness 5

10

10

15
10

15

20
10

10

MILK.

Handling .121
Storage .... ..... 8 f

SALES ROOM.

Location ... 2 }
Construction ... 2 [
Equipment..... 2 (
Cleanliness 4J

WAGONS.

General appearance 2 j
Protection of product ..3 V
Cleanliness 5 J

Total

, 100

Sanitary conditions are . .
Suggestions by inspector

Excellent.

Good.

.Fair Poor

Signed ....

Inspector.

108 MUNICIPAL SANITARY CONTROL OF MILK.

\ Reverse.'}

SANITARY INSPECTION OF CITY MILK PLANTS.
DIRECTIONS FOR SCORING.

MILK ROOM.

Location. — If not connected by door with any other building, and sur-
roundings are good, 10; when connected with other rooms, such as
kitchens, stables, etc., make deductions according to conditions.
Construction. — If good cement floor, and tight, smooth walls and ceil-
ings, and good drainage, allow 10; deduct for cracked or decayed floors,
imperfect wall and ceiling, etc.

Cleanliness. — If perfectly clean throughout, allow 15 ; deduct for bad
odors, unclean floor and walls, cobwebs, unnecessary articles stored in
room, etc.

Light and ventilation. — If window space is equivalent to \5% or more
of the floor space, allow 5; deduct 1 point for every 3$ less than the
above amount.
Equipment:

Arrangement. — Allow 3 points for good arrangement; if some of the
equipment is out of doors or so placed that it can not be readily
cleaned, make deductions according to circumstances.
Condition. — If in good repair, allow 4 points; make deductions for

rusty, worn-out, or damaged apparatus.
Construction. —

Sanitary: If seams are smooth, and all parts can be readily cleaned,

allow 2. Deduct for poor construction, from sanitary standpoint.

Durability: If made strong and of good material, allow 2. Deduct

for light construction and poor material.

Cleanliness. — If perfectly clean, allow 8 points; make deductions ac-
cording to amount of apparatus improperly cleaned.

MI^K.

Handling. — If milk is properly cooled to 50° F. or lower, allow 12 points;
or if pasteurized at a temperature of 149° F. or above and promptly
cooled to 50° or lower, allow 12 points. Deduct 1 point for every
2° above 50°. If milk is pasteurized imperfectly, deduct 6 points. If
milk is improperly bottled or otherwise poorly handled, make deduc-
tions accordingly.

Storage. — If stored at a temperature of 45° F. or below, allow 8 points;
deduct 1 point for every 2° above 45°.

SALES ROOM.

Location. — If exterior surroundings are good and building is not con-
nected with any other under undesirable conditions, allow 2; for fair
conditions, allow 1; poor conditions, 0.

INSPECTION. 109

Construction. — If constructed of material that can be kept clean and sani-
tary allow 2; for fair construction, allow 1; poor construction, 0.

Equipment.— If well equipped w4th everything necessary for the trade,
allow 2; fair equipment, 1; poor equipment, 0.

Cleanliness. — If perfectly clean, allow 4 points; if conditions are good, 2;
fair, 1; poor, 0.

WAGONS.

General appearance. — If painted and in good repair, allow 2 points ; for

fair condition, 1; poor, 0.
Protection of Product. — If product is iced, allow 3 points; well protected

but not iced, 1; no protection, 0.
Cleanliness.— ?If perfectly clean, allow 5; good, 3; fair, 2; poor, 0.

The regulation of methods of pasteurizing milk is one of the
newer problems that must be met in city inspection work.
(See Appendix B.)

Milk-borne epidemics. Present methods of inspection do not
prevent the occurrence of numerous epidemics of typhoid fever,
diphtheria and scarlet fever. Much can be done in the way
of recognizing such outbreaks early, and in correcting condi-
tions at the source of trouble. The health officer should inves-
tigate the milk supply, and other possible sources of infection,
of all reported cases of these diseases, and keep a record of
their distribution with reference to the various dairymen.
When a dairyman shows a suspicious number of cases, due
consideration being given to the size of his business and the
general prevalence of the disease, the matter should be in-
vestigated. (See Chap. III.) Pasteurization (Chap. VI) seems
to be the only way of preventing outbreaks of milk-borne dis-
ease.

The Department of Health of the City of New York has
regulations requiring a report every week concerning the exist-
ence of infectious diseases among those handling milk. The
dairymen are required to report to the manager of the shipping
station and he in turn notifies the health department. Kven
if these regulations were uniformly obeyed they would not
protect against bacilli carriers. (See Appendix D.)

Temperature standard. New York, Boston, and other cities
require that milk be immediately cooled to 50°F. or below,

110 MUNICIPAL SANITARY CONTROL OF MILK.

and that it shall not exceed this temperature before delivery.
The requirement is desirable, and does not necessitate compli-
cated methods of examination. This regulation very properly
necessitates the use of ice at the producing farm, and the use
of refrigerator .cars where the milk is transported long dis-
tances. Its strict enforcement tends to eliminate the sale of
milk from stores where adequate refrigerating facilities are not
provided .

In a large area of the country, the Southern States and
California, the universal enforcement of such a standard is
out of the question because of the absence of natural ice. In
large dairies, artificial refrigeration may be used, but the smaller
producers could not afford the expense.

Numerical determinations of bacteria in milk. Bacterial counts
may be made to yield valuable information when conditions
that will permit the comparison of results are maintained. The
first requisite is the practice of uniformity in technic. Under
such conditions, the examination of the milk from time to
time from samples of the same age will reveal significant devi-
ations from the usual. Then an unusually high count wrill
indicate the effect of the combination in some proportion of
the factors of uncleanliness, age and poor cooling.

Numerical determinations of bacteria are an index of the
care exercised in the handling of milk. A sufficient number
of determinations give results that permit the classification of
dairies in a general sort of way. Systematic counting of bac-
teria in a city milk supply encourages better methods. Rela-
tively high counts Occurring uniformly are unmistakable evi-
dence of bad management.

Nice distinctions among dairies supplying a city cannot be
made on the .basis of a variation of a few million bacteria per
cc. in the milk. The instrument of measurement is too deli-
cate in such cases and the distinctions revealed too fine.

Effective work calls for faithful attention to details of technic
and for numerous determinations. Tests made at rare inter-
vals from samples of normally bad milk, varying considerably
in age, represent the lowrest degree of usefulness of the work.
The sensational publication of such results does not materially

INSPECTION. Ill

protect the public or educate the dairymen. Unless bacterial
counts are made carefully by competent persons from samples
properly collected and cared for, they had best not be made at
all. This is equally true in cases where the inspecting staff
is too small or too inefficient to accomplish the work thor-
oughly.

In cities like Boston (10), Rochester (7) and Washington
(15), bacterial counts in connection with inspection work have
been made on a scale that has been regarded as productive of
good results. The average bacterial count of the milk of
Rochester declined in three years to one-fourth of the numbers
prevailing before such work was undertaken (6).

The results of two years' work with a bacterial standard in
Boston have been summarized as follows by Jordan (10):

TABLE VI.
NUMBER OF BACTERIA IN THE BOSTON MILK SUPPLY.

1905. 1906.

Samples showing under 500,000 bacteria per cc 87.60% 89.98%

Samples showing above 500,000 bacteria per cc 12.40% 10.02%

Samples showing under 50,000 bacteria per cc 59.80% 62.33%

Samples showing under 100,000 bacteria per cc 74.90% 72.67%

As is usually the case, the determination of standards has
been a matter of difficulty. They have been set on the basis
of the justifiable assumption that germ free milk is the ideal
milk. Then, after a survey of the conditions as regards num-
bers in the ordinary supply, a standard has been set low
enough to interfere only with the worst producers. Boston set
a limit of 500,000 per cc. for ordinary city supply, and has
been pretty generally followed. Various finer grades of milk
elsewhere have had higher standards, for instance, inspected
milk, 100,000 per cc. Certified milk almost uniformly has a
standard of 10,000 per cc. A bacterial standard need not be
the subject of legislation, and the work may be merely carried
on as a guide to inspection work.

112 MUNICIPAL SANITARY CONTROL OF MILK.

Bacterial counts take so long to carry out that they do not
afford protection against the use of any given lot of highly
polluted milk. An exception to this is afforded when Slack's
method for the direct microscopic estimate of numbers is used.
Ordinary counts do, however, discourage the habitual occur-
rence of such conditions. The method of making numerical
determinations is described in Chap. VIII, and other labora-
tory methods are discussed in Chap. VII.

Education of the public. The general public must be in-
formed concerning the significance of clean milk. The market
for cheap, dirty milk must be destroyed as far as possible by
the education of the public concerning its significance. Clean
milk costs more, but people will not pay the increased price
until they see the advantage. In matters concerning legisla-
tion and prosecution, the support of the public is desirable, if
not indispensable.

The publication of the results of scoring dairies, showing
their relative standing is a useful educational factor. This
must be done circumspectly to avoid damage suits instituted by
those dairymen who do not make a favorable showing. It
seems safe to convey these facts in an official report, for in-
stance, by the inspector or health officer to the board of health.
This report may be given wide publicity in the press as a part
of the proceedings of the board. Before going farther than
this it would be well to determine the possible consequences.

Public education should include matters concerning the care
of milk in the home, such as cleanliness of utensils, refriger-
ation, home pasteurization and the keeping qualities of pas-
teurized milk.

The agents for accomplishing educational work may include
leaflets published by the board of health, the press, lectures
before civic organizations, women's clubs, etc.

REFERENCES.

1. BOI/TON. Sanitary water supplies for dairy farms. Bui. No. 41,
Hyg. Lad., ('. S. Pud. Health and Mar. Hosp. Sen'., Washington, D.
C., 1908, p. 527.

RKFKRKNCES. 113

2. BOSTON. Methods and results' of the examination of water sup-
plies of dairies supplying the District of Columbia. Bui. No. 41, Hyg.
/.ah., I'. S. Pub. Health and Mar. Hasp. Sen'., Washington, D. C.,
1908, p. 543.

3. CONFERENCE APPOINTED BY THE COMMISSIONERS OF THE DISTRICT

OF COLUMBIA. Sanitary milk production, dr. No. 114, Bur. Anhn.
I mi., ('. S. Hcpt. Agr., Washington, D. C.,1907.

4. DARLINGTON. The methods of dealing with the milk supply of
New York City. Jour. Aiucr. Med. Assoc., Vol. XUX, 1907, p. 1079.

5. FRASER. City milk supply. Bui. No. 92, Univ. of III. Agr. Exp.
Sta., Urbana, 111., 1903.

6. GOLER. The influence of the municipal milk supply upon the
deaths of young children. N. Y. State Jour, of Med., Vol. Ill, 1903,
p. 493.

7. GOLER. Does the bacterial content of city milk influence the in-
fantile death rate? Archiv. Fed., September, 1906.

8. HEINEMANN. Sanitary milk. Arch. Fed., June, 1908.

9. JAFFA and WARD. Investigations of the San Francisco milk sup-
ply. Nineteenth Biennial Report of the State Board of Health of Cali-
fornia, p. 122.

10. JORDAN. Boston's campaign for clean milk. Jour. Amer. Med.
Assoc., Vol. XUX, 1907, p. 1082.

11. LANE and WELD. A city milk and cream contest as a practical
method of improving the milk supply. Cir. No. 117, Bur. Anhn. Ind.,
r. 5. Dept. Agr., Washington, D. C., 1907.

12. L/EVY. Monthly Bulletin of the Health Department. Richmond,
Va., Vol. II, 1908, No. 4.

13. MAYOR'S MILK COMMISSION. Report on the milk supply of New
York City, with recommendations. Arch. Ped., February, 1908.

14. RAYNOR. What rigid inspection of milk is doing for New York
City. N. Y. State Jour, of Med., Vol. VIII, 1908, p. 252.

15. ROSENAU. The number of bacteria in milk, and the value of
bacterial counts. Bui. No. 41, Hyg. Lab., U. S. Pub. Health and Mar.
Hosp. Serv., Washington, D. C., 1908, p. 421.

16. TRUEMAN. Milk supply of Chicago and twenty-six other cities.
Bui. No. 120, Univ. of III. Agr. Exp. Sta., Urbana, 111., 1907.

17. WEBSTER. Sanitary inspection and its bearing on clean milky
Bui. No. 41, Hyg. Lab., U. S. Pub. Health and Mar. Hosp. Sen£,
Washington, D. C., 1908, p. 511.

18. WOODWARD. The municipal regulation of the milk supply of/
the District of Columbia. Bui. No. 41, Hyg. Lab., U. S. Pub. Health
and Mar. Hosp. Serv., Washington, D. C., 1908, p. 679.

CHAPTER VI.

PASTEURIZATION OF MILK,

General definition* Pasteurization is a generic term refer-
ring to various processes of heating milk, followed by cooling.
The temperatures involved vary from 140°F. (60°C.) to 185°F.
(85°C.) and the length of time of exposure to these tempera-
tures varies from a few seconds to thirty minutes. A consider-
able number of pasteurizing machines designed to accomplish
the heating of the milk in various ways are in use, and in
actual practice do their work with varying degrees of uni-
formity. The temperature to which the milk is finally cooled,
an important factor in the efficiency and value of the process,
likewise varies. Another element leading to diversity of
results is the bacteriological quality of the milk treated by the
processes. Notwithstanding the widely differing processes
designated by " pasteurization," the term unfortunately is con-
stantly used without qualification to indicate the precise process
designated.

Sterilization, a term frequently used in the discussion of the
subject of heated milk, properly refers to a process by which
all bacteria and their spores are killed by heat. This in con-
nection with the preservation of milk involves an exposure to
heat above the boiling point. It is employed in the preser-
vation of canned milk and never in connection with ordinary
market milk.

Incentives for pasteurization. The destruction of pathogenic
bacteria has been the chief incentive to the development of
pasteurizing processes. The effect of heating in enhancing
the keeping quality of milk is a valuable result which also has
stimulated interest in the process. Methods for preserving
milk are not necessarily the same as for killing pathogenic bac-
teria, although the converse is true.

ALTERATION OF MILK BY HEAT. 115

Conditions required for killing bacteria. Temperature and
time of exposure are important factors with reference to meth-
ods of killing bacteria by heat. A high temperature foi^a
short time is equally as efficient as a lower temperature for a
longer time.

Bacterium tuberculosis. This is the most common of the
pathogenic organisms found in milk, and at the same time the
one of them most resistant to heat. Therefore it has been used
as a basis for determining methods of pasteurizing, with proper
regard to other considerations not concerning bacteria. The
fact that 140°F. (60°C.) for twenty minutes is fatal to Bacterium
tuberculosis is abundantly confirmed (13, 16, 20). This is
•equally true of the other pathogenic bacteria like B. diphtheria'
and B. typhosus, occasionally disseminated in milk (13).

To kill the tubercle bacterium, when the time of exposure
of heat is shortened to one minute or less, the temperature
must be 160°F. (71°C.) or more (6, 18). B. diphtheria (13)
and B. typhosus (9) are destroyed in like manner.

.Alteration of milk by heat. The bacteriological requirements
are by no means the only factors in the problem, for the heating
of milk presents a formidable array of obstacles that must be
avoided in formulating pasteurization processes. These in-
volve all sorts of considerations, from those concerning the
chemical constitution of the heated milk with respect to nutri-
tion, to the practical requirements of the milk trade.

Cooked taste. This is left permanently in milk by exposure
to about 158°F. (70°C.) for fifteen minutes. Exposure to
170°F. (76.6°C.) in a closed vessel, followed by immediate
cooling, is the highest temperature that may be used without
leaving the cooked taste. Ten minutes at 160°F. (7l°C.) is
safe.

Alterations of milk constituents. The chemical constitution
of milk is not appreciably altered by exposure to 140°F. (60°C.)
for a short time. At about 140°F., milk heated with exposure
to air forms a thin pellicle on the surface, consisting of casein
and albuminoid matter. This is probably due to the drying
of the upper layer of the milk and does not occur in closed
vessels. Higher temperatures, especially near the boiling

116 PASTEURIZATION OF MILK.

point, bring about profound changes. The .significance of
these, in connection with the digestibility of the altered con-
stituents, has been widely discussed. Important manifestations
of the effect of heat on milk concern temperatures higher than
those necessary for pasteurization.

Creaming quality . Exposure to heat above certain limits so
alters the physical constitution of milk that the cream does not
rise naturally but remains more completely emulsified. The
public judges milk largely by the amount of cream that rises,
especially in the case of bottled milk where the location of the
"cream line" is so easily detected. The same causes that
operate in this regard in milk affect market cream. The
" body " is lessened, the cream looks of a poorer quality than
it really is, its whipping quality is affected, and consequently
its salability is impaired. These are weighty considerations
and the application of heat must conform to them. Exposure
to 160°F. (71°C.) for one minute, or long exposures at 140°F.
(60°C.) are both safe (2).

Vital qualities of milk. Milk has certain vital qualities,
whose sensitiveness to heat deserves especial consideration with
respect to the use of heated milk as infant food. Among these
are the proteolytic, oxidizing, and fat splitting ferments.
Here, too, may be mentioned the alexins, according to Von
Behring, and the agents causing the so-called " germicidal "
phenomenon, probably agglutinins. An exposure to not more
than 140°F. (60°C.) for forty minutes avoids the impairment of
all these qualities of milk (3, 5).

Spore- bear ing bacteria. Spores of bacteria in milk are not
killed by one exposure to heat unless it is above 212CF. Any
of the processes of pasteurization will fail to kill bacterial
spores, that ordinarily constitute less than \% of the bac-
teria present. The hygienic significance of spore-bearing
bacteria in such small numbers in fresh pasteurized milk is of
no consequence, and the fact of their survival has been of
necessity ignored in formulating methods of pasteurization.
Their significance in old pasteurized milk has been the subject
of considerable discussion. The varying percentage of spores
in different lots of milk results in the variation of the bacteri-

LOW -TEMPER ATURE PASTEURIZATION. 117

cidal efficiency of a pasteurizing machine at different times,
even if run under constant conditions.

Bactericidal efficiency. Russell (15) has shown that an
exposure to 140°F. (60°C.) for twenty minutes results in the
destruction of as great a number of bacteria as exposure to
higher temperatures for the same time. The bacteria remain-
ing alive after exposure to 160°F. were in spore form, and were
uninjured by the higher ranges of temperature. Milk which
would ordinarily sour in two days would keep fresh for six
days when pasteurized at 140°F. for fifteen to thirty minutes
(2). Over 99% of the bacteria were killed.

Low-temperature pasteurization* The various limitations to
the application of heat for the purpose of killing bacteria per-
mit the use of 140°F. (60°C.) for twenty minutes. All the
physical, chemical and bacteriological considerations involved
favor the selection of this combination of time and temper-
ature, for it presents the widest margin of safety from violation
of the limiting conditions.

The earliest machines for accomplishing low temperature
pasteurization embodied the idea of heating a definite quantity
of milk, -with proper agitation, to the required temperature,
after which the milk was rapidly chilled. The principle of a
reservoir, alternately filled and emptied, is common to many.
In some, heating and chilling the milk are accomplished in the
same chamber. The process of intermittent pasteurization in
the reservoir type of machine necessitates considerable expense
for labor and is slow. These considerations have largely pre-
vented the general employment of the type of machine in ques-
tion. There are no insurmountable difficulties in the way of
the development of machines for accomplishing low temper-
ature pasteurization at a rate of speed and low cost appropriate
to the demands of milk distributers. There are now on the
market machines designed to hold the milk at a given temper-
ature for twenty or thirty minutes, and at the same time
permit continuous operation. The milk is first heated and
then passed through a ' ' holding device ' ' by which the desired
temperature is maintained for the proper time.

The pasteurizing process may be carried out in the house-

118 PASTEURIZATION OF MILK.

hold with kitchen utensils, it being necessar\^ to purchase only
a thermometer. The bottles of milk for individual feeding of
the infant are placed in a covered vessel of water provided with
some simple device, like a perforated pie tin, to keep the milk
bottles from touching the bottom. The vessel and contents
are heated on the stove until the water reaches 155°F. The
whole is removed and allowed to stand for half an hour, after
which the bottles of milk are rapidly chilled.

High-temperature pasteurization. The demand for speed
and economy has been a factor in the development of pasteur-
ization at high temperatures for a short time. The heating is
accomplished in various styles of continuous-flow machines,
iii which the milk passes over heated surfaces in a thin layer.
The range of temperature extends from 176°F. (80°C.) to 185°F.
(85°C.), and the time of exposure varies from a few seconds
upwards. The momentary exposure to 176°F. (80°C.) is con-
siderably above that necessary to satisfy the requirement for
killing tubercle bacilli. The higher limit has been found
necessary to compensate for defects in the thoroughness with
which the continuous-flow machines do their work. As a class
the machines are defective, in that all the milk passing through
may not be heated to the desired temperature. This is attribu-
table to a fundamental characteristic of the behavior of fluids.
The parts of the stream not in actual contact with the heated
surfaces will flow more rapidly than those portions influenced
by friction. The employment of a temperature as high as
176°F. (80°C.) violates conditions required for market milk
in the United States, but the process is unobjectionable in milk
used for butter-making and is extensively employed in Den-
mark for this purpose.

Commercial pasteurization. A modification of the foregoing
method, by the use of the same types of continuous-flow
machines, is quite generally used -for the purely commercial
purpose of preventing the souring of milk. It hides, and par-
tially undoes, the results of filthy methods of production and
poor care in shipment.

The temperatures vary from 140° to 165°F. (60° to 74°C.),
more often the lower temperature, followed by rapid cooling.

HIGH-TKMPERATURK PASTEURIZATION. 119

The time occupied by the milk in passing through the machine
is varied at the will of the operator, from a fraction of a min-
ute to two minutes. The fact that this method of treating milk
has come into practice without consideration of its effect upon
the pathogenic organisms becomes evident when attention is
paid to the literature on the thermal death point of the tubercle
bacterium in milk at temperatures between 140° and 160°F.
At 140°F (60°C.), the shortest length of time that has been
found permissible is fifteen minutes (20). Heating milk to this
temperature or even several degrees above for a minute or less
is a long way from the conditions insuring the death of the
tubercle organism. Hess (Ref. 9, Chap. IV) has noted the
deficiencies of commercially pasteurized milk as regards de-
struction of tubercle bacilli. It is only when the temperature
of the milk during the heating for brief periods approaches
160°F. (71°C.) that evidence is found to justify the belief that
pathogenic organisms are killed.

There seems, then, to be justification for placing confidence
in a pasteurization process, as a means for destroying patho-
genic bacteria, in which all the milk is actually exposed for
half a minute, or even momentarily, to a temperature, of 160°F.
(71.1°C). The statement need not necessarily imply an
adherence to that system of pasteurization for rendering milk
safe as against a system employing lower temperatures for
longer periods. Commercial high-temperature pasteurization
has narrow limits of safety bounded, on the one hand, by alter-
ations in the physical characteristics of the milk, and on the
other hand, by the danger of not killing pathogenic bacteria.
The temperature zone in question comprises 160° to 165°F.,
and therefore the possibilities of negligence in running the
apparatus, or intentional lowering of the temperature for com-
mercial reasons, are obvious. There is always the possibility
that the machine in use may not heat all portions of the milk
uniformly to the temperature desired.

Efficiency. Efficiency tests of pasteurization must be inter-
preted with care. The bacteria remaining should not be com-
pared, with respect to either numbers or character, with
those in uuheated milk. The character of the organisms in

120 PASTEURIZATION OF MILK.

heated milk, and the medium in which they are present, en-
tirely preclude comparisons with ordinary milk showing a
similar count.

Prescott (10) found in a series of 32 observations, from
samples containing mostly less than a million, that a machine
at an average temperature approximately 164°F. attained an
average percentage efficiency of 97.1% . The bacteria remain-
ing in the milk averaged 14,000 per cc. and the average
temperature of the pasteurized milk was 40°C. Very bad
milk, three to nine million, showed the high efficiency of
99.1%, with an average of 55, 090 per cc. left alive. In regu-
lar practice the conditions for highest efficiency were not
always maintained. Russell (15) has summarized the results
of a number of such tests made by himself and others.

Continuous-flow machines popular. The commercial interests
have refused to adopt generally the discontinuous or tank type
of pasteurizing machine for market milk, on account of
expense and time consumed, although it is used for cream.
The rapid, cheaply operated, continuous flow machine, run-
ning at 140° to 165°F., is a factor in the market milk business
to-day. Lederle (8) estimates the expense of treating milk by
this process to be from one-tenth to one-quarter of one cent
per quart. However much bacteriologists may prefer the use
of 140°F. for twenty minutes, the other practice is deeply
rooted. It has been estimated that one-quarter of the milk
sold in New York is pasteurized and about one-third of that in
Boston (12).

Under the circumstances, it seems that a fruitful field for
persuasive educational effort is furnished by those instances
where the machine is so run that the milk is exposed too short
a time at a temperature below 160°F. It is entirely possible
to expose milk to 160°F. for a minute or even two, without
injuring the cream line or flavor, although it probably does
impair certain vital characteristics. Effort should be made to
have the machines run at 160°F. with the flow of milk slow
enough to permit exposure to the heat for at least one minute.
Better yet, the employment of machines heating to 140°F. for
twenty or thirty minutes should be encouraged.

PASTEURIZATION IN CHICAGO. 121

Care subsequent to heating* The milk must be rapidly and
thoroughly chilled after heating. The process of pasteuriza-
tion should include cooling to at least 50°F., and any regula-
tions denning the process should make reference to the cooling.
Unless cooled, the few bacteria that have survived the heating
will multiply in the warm milk at an enormous rate. Any
opportunities offered for contamination subsequent to heating
will speedily undo the beneficial work done by the heat. The
method of handling pasteurized milk for infant feeding illus-
trates an ideal way of avoiding subsequent contamination.
The milk is pasteurized in the containers from which the
baby is fed.

In connection with this subject, interest attaches to some
recent amendments to the sanitary code of the Board of Health
of New York, as follows :

"1. Pasteurization of milk must he carried out under a permit therefor
issued by the Board of Health, in addition to the usual permit for milk
required by Section 56 of the Sanitary Code.

"2. The milk after pasteurization must be at once cooled and placed
in sterilized containers, and the containers sealed.

"3. All pasteurized milk must be delivered to the consumer in sealed
containers which are plainly labeled 'pasteurized.' The labels must also
bear the dat£ and hour when the pasteurization of the milk was comple-
ted, the degree of the heat employed, the length of time exposed to the
heat, and the number of the pasteurization permit issued by the Board
of Health.

4 ' 4. Pasteurized milk must be delivered to the consumer within twenty-
four hours of the pasteurization.

"5. No milk shall be pasteurized a second time."

Pasteurization in Chicago, Recent legislation in Chicago
requires not only the pasteurization of all milk obtained from
non-tested cows but also requires that all butter, cheese,
buttermilk, cream and ice cream shall be derived from pasteur-
ized milk unless the cows are free from tuberculosis. A num-
ber of new administrative difficulties are involved, such as
inspection of pasteurization, and results of the experience with
the Chicago ordinance will be awaited with interest. See
Appendix B.

122 PASTEURIZATION OF MILK.

Pasteurized milk in infant feeding. The use of heated milk
for infant feeding is widely prevalent. There is abundant
medical testimony to the effect that properly heated milk is
harmless, and that the general adoption of its use is an impor-
tant factor in saving life ( 12) . On the other hand, experienced '
specialists in pediatrics vehemently object to the long-continued
use of heated milk for infant feeding and point with truth to
cases that are unable to tolerate heated milk.

The literature of the subject is voluminous, but the discus-
sion in general has not been concerned with clear-cut issues.
The temperatures to which milk has been exposed in the past,
and even now, are higher than necessary. All sorts of tem-
peratures have been used and insufficient distinction has been
drawn between sterilized and pasteurized milk. Reference has
been made to the possible effect of toxins of bacterial origin
remaining active in heated milk, but really very little is known
concerning them. It has been asserted that the few spore-
bearing bacteria surviving the heating would subsequently
multiply very rapidly with harmful effect. It has been shown
however that, with proper refrigeration, multiplication goes on
slowly (ll). The issues to be determined have been clouded
by the interjection of ideas regarding the effect that the gen-
eral practice of pasteurizing would have on the care exercised
by producers. The writer is not yet convinced that there is a
strong case against the use of milk heated to 140°F. for twenty
minutes. Now that this desirable kind of pasteurization is in
use, it would be well to take up on a large scale the study of
the effect of this milk upon infant morbidity and mortality, as
compared with unheated milk. The whole controversy con-
cerns only the effect of heated milk on children of less than
three years of age. There are special agencies for the supply
of milk for infant feeding, and more will be provided in the
future. Under these conditions, one may very well question
the advisability of viewing the whole problem of municipal
milk inspection from the standpoint of its use for the few
infants who are unable to tolerate heated milk. Rosenau (12)
discusses the matter fully.

PASTEURIZATION OK MUNICIPAL MILK SUPPLIES. 123

Pasteurization of municipal milk supplies. The subject of
the pasteurization of milk assumes great importance in con-
nection with the transmission of epidemic diseases of man.
There has been collected a formidable list of instances in which
milk has transmitted .scarlet fever, diphtheria and typhoid fever.
The work in Washington shows that 10% of the typhoid fever
cases are plainly attributable to milk. In that city, of the
dairymen delivering over 100,000 gallons of milk during the
summer months, the one having the lowest typhoid fever rate
among his customers has a thoroughly up-to-date system of
sterilizing bottles and of pasteurizing milk by a holding-device
type of machine.

The system of dairy inspection of the District of Columbia
is not preventing milk-borne typhoid fever. All that can be
done is to detect outbreaks as early as possible, correct the
conditions at the dairy, and count the cases of typhoid fever
as they continue to appear. This is not said in disparagement
of the Health Department of the District government, for it is
under able, conscientious management.

The facts brought to light in Washington regarding typhoid
fever alone indicate the necessity for pasteurization, and if
subsequent work elsewhere brings to light similar conditions
as regards this and other milk-borne diseases, the evidence for
the necessity of pasteurization will be overwhelming. Cer-
tain it is, that pasteurization offers the only effective measure
that may be immediately put in force against the danger from
bovine tuberculosis. That disease is so widely prevalent that
the rigicl application of measures against the sale of milk from
tubercular cows without the alternative of pasteurization would
cause a milk famine.

There have been opinions expressed to the effect that pas-
teurization would discourage the exercise of cleanliness and
care of milk by the producers. This need not be worse than
at present if inspection methods are thorough. As a matter of
fact, pasteurization is not lessening the demands for care in pro-
ducing milk. A number of instances could be pointed out of
dairymen who pasteurize but keep the producers up to a high
standard by counting the bacteria in the milk and by a private
inspection service.

124 PASTEURIZATION OF MILK.

REFERENCES.

1. DOANE and PRICE. The comparative digestibility of raw, pasteur-
ized and cooked milk. Bui. No. 77, Maryland Agr. Exp. Sta., College
Park, Md., 1901.

2. FARRINGTON and RUSSELL. Pasteurization of milk and cream
at 140° F. Sixteenth Ann. Kept., Agr. Exp. Sta. Univ. of Wis., Mad-
ison, Wis., 1899, p. 129.

3. FREEMAN. The ferments of milk and their relation to pasteur-
ization. Jour. Amer. Med. Assn., Vol. XLJX, 1907, No. 21, p. 1740.

4. FREEMAN. Pasteurization : The advantages and disadvantages to
the consumer. N. Y. Med. Jour., March 23, 1907.

5. HIPPIUS. Biologisches zur Milchpasteurisierung. Jahrb. Kinder-
heilk., Bd. L/XI, 1905, S. 365.

6. JENSEN, translated by LEONARD PEARSON. Essentials of milk hy-
giene, etc. Philadelphia : J. B. Lippincott Company, 1909.

7. JENSEN et PLATTNER. De 1'action du chauffage sur le lait de vache.
Rev. Gen. Lait, 4e Annee, 1905, No. 16, p. 561, etc.

8. L/EDERLE. Pasteurization of milk. Amer. Jour. Pub. Hyg., O.
S. Vol. XVII, 1907, No. 2, (N. S. Vol. Ill, No. 3), p. 164.

9. PARK. Current misstatements and fallacies regarding the milk
and milk supply of New York City. Medical Record, Vol. IvXXI,
March 23, 1907, p. 501.

10. PRESCOTT. The efficiency of commercial pasteurization and its
relation to the milk problem. Technol. Quar., Vol. XVIII, 1905, No.
3. p. 247.

11. ROGERS. The bacteria of pasteurized and unpasteurized milk un-
der laboratory conditions. Bui. No. 73, Bur. Anim. Ind., ( '. S. Dept.
Agr., Washington, D. C., 1905.

12. ROSENAU. Pasteurization. Bui. No. 41, Hyg. I^ab., U. S. Pub.
Health and Mar. Hosp. Sen'., Washington, D. C., 1908, p. 591.

13. ROSENAU. The thermal death points of pathogenic micro-organ-
isms in milk. Bui. Aro. 42, Hyg. Lab., U. S. Pub. Health and Mar.
Hosp. Serv., Washington, D. C., 1908.

14. ROTCH. Pasteurization of milk for public sale. Amer. Jour.
Pub. Hyg., O. S. Vol. XVII, 1907, No. 2, (N. S. Vol. Ill, No. 3), p. 181.

15. RUSSELL. Outlines of dairy bacteriology. Madison, Wis.: H. L,.
Russell.

16. RUSSELL and HASTINGS. Thermal death point of tubercle bacilli
under commercial conditions. Seventeenth Ann. Rept., Agr. Exp. Sta.
Univ. of Wis., Madison, Wis., 1900, p. 147.

REFERENCES. 125

17. RussKLiv and HASTINGS. On the increased resistance of bacteria
in milk pasteurized in contact with air. Eighteenth Ann. kept., Agr.
E.vp. Sta. I'nii*. of Wis., Madison, Wis., 1901, p. 185.

18. RUSSKU, and HASTINGS. Effect of short periods of exposure to
heat on tubercle bacilli in milk. Twenty-first Ann. Rept., Agr. Exp.
Sta. i'niv. of Wis., Madison, Wis., 1904, p. 178.

19. Russian and HOFFMANN. Bacteriological examination of milk
pasteurized in Miller apparatus. Twenty-second Ann. Rept., Agr. Exp.
Sta. I'niv. of Wis., Madison, Wis., 1905, p. 236.

20. SMITH. The thermal death point of tubercle bacilli in milk and
some other fluids. Jour. E.rpcr. Med., Vol. IV, 1899, No. 2, p. 217.

21. SPARGO. T.he common sense of the milk question. New York:
The Macmillan Company, 1908.

CHAPTER VII.

MICROSCOPIC TESTS OF MILK.

Mammitis in the cow. Cows very frequently suffer from
mammitis associated with the presence of streptococci. The
majority of dairies contain cows that show active inflammatory
changes in one or more quarters of the udder. The abnormal
product of such an udder always contains pus cells and strep-
tococci. Clinical manifestations of the disease vary from the
case exhibiting marked swelling of the udder, with a marked
abnormal secretion, down through various gradations of clinical
manifestations as exhibited through the condition of the udder
or secretion, to the normal (34). More than this, bacteri-
ological study of some apparently healthy udders reveals
streptococci in the whole organ or in particular quarters of the
udder. Sometimes in these cases'a history of a previous attack
of mammitis may be established by inquiry or by the discovery
of indurated portions of the udder by palpation, and other
times not.

Tests for cellular content of milk. The development of
microscopic tests of milk has been actuated by a desire to
determine quickly which cows supplying city milk are suffer-
ing from garget and yielding pus cells and the accompanying
organisms of suppuration. The examination of a large num-
ber of milk samples in a city bacteriological laboratory by a
fairly rapid, accurate method would perhaps obviate numerous
visits to the dairies. In case of -positive results, the dairies
might be visited and inspected for udder disease or the milk
of the individual animals in turn examined by the same test as
a more delicate method than physical examination for selecting
those cows yielding pus cells.

Stokes' test. Stokes (29) centrifugalized 10 cc. of milk,
smeared the sediment on a cover glass and stained. When

TKSTS 1'OK CKLLULAR CONTENT OF MILK. 127

upon microscopic examination " an excessive amount of pus "
was found in a sample of herd milk the examination of the
individual cows was suggested. The presence of more than 5
pus cells per field of a one-twelfth objective in the milk of an
individual cow was regarded as justification for the exclusion of
the cow7 from the herd. The original article describing the
test contained results of the examination of a series of cows,
one-third of which were condemned on the basis of the stand-
ard selected.

Bergey (3, 4. 5) found it necessary to lower the standard
and regarded 10 cells per field as an indication of pus associ-
ated with inflammatory reaction of the udder caused by pyo-
genic organisms.

Stewart's test. Stewart (28), of the Philadelphia Bureau of
Health, further modified the method and applied it to the
examination of large numbers of samples of mixed herd milk.
He describes the apparatus and method as follows :

' ' This apparatus consists of a circular pan about 12 inches in diameter,
and -'4 -inch deep, containing twenty small glass tubes. The tubes con-
tain 1 cc. of milk and are filled by means of a small bulb similar to that
ordinarily used on medicine droppers. The end of the tube is closed by
a small rubber stopper, and the tubes are held in the pan by spring
clamps. This pan is fitted upon the ordinary Boekel • water centrifuge
and covered with a lid which is held down by a thumbscrew. The pan
covered in this way furnishes a surface of very slight resistance to the
atmosphere during its revolution, somewhat on the principle of a child's
top.

' ' By the old method the arms of the centrifuge containing the milk
encountered so much resistance in their revolution that the speed with
15 pounds water pressure was not more than 1,200 revolutions per minute,
while the speed obtained with the new apparatus is from 2,500 to 3,000
revolutions per minute with 15 pounds pressure. This rapid speed
causes sedimentation to occur in less than five minutes. When this is
completed the centrifuge pan can be lifted from the motor and the per
cent, of cream measured by a graduated scale marked upon the tube.
The heavier matter, as the insoluble dirt, pus cells and bacteria, is thrown
to t?he peripheral end of the tube, where it adheres to the rubber cork in
the lumen of the tube. To examine this sediment, the cork is carefully
removed and a spread made by rubbing the cork containing the sediment
over an area of a square centimeter on a 3-inch by 6-inch glass slide.
The proper area of the smear is obtained by placing underneath the slide
a scale of circles having an area of a square centimeter. After the

128 MICROSCOPIC TKSTS OF MILK.

smears are dried in air without fixation by heat, the preparation is stained
with the Jenner blood stain for two minutes, keeping the stain in con-
stant motion. The excess of stain is washed off in water, and the prep-
aration is dried in air. By this blood-staining method, the pus and blood
cells are stained perfectly, and the ordinary microorganisms take the blue
stain well.

"The stained specimens are examined with a one-twelfth Leitx. objec-
tive and a No. 3 eye-piece. The character of the bacteria is noted, and
the average number of pus cells per field is counted. This average num-
ber is multiplied by 4,400, since there are about 4,400 fields to a square
centimeter, as estimated by the stage micrometer. This result is approxi-
mately the number of pus cells per cubic centimeter of milk."

When a sample of milk showed over 100,000 cells per cc.,
or showed "streptococci and the ordinary pus producing organ-
isms," an examination of the herd was ordered. Stewart
gave figures showing that inspections of condemned herds by
veterinarians, revealed diseased animals in those herds.

The quantitative features of the test have not been found
accurate. The average percentage variations between dupli-
cate determinations have been found to be 112% in a series of
-23 determinations made by Russell and Hoffmann (23, 24).
The present writer and associates (32) also noted its very unsat-
isfactory behavior. The numerical results are always very
much below the true number present and bear no constant
ratio to the true number.

The test very rarely indicates the presence of streptococci,
even though streptococci are proven by other methods to be
very common in the milk. The presence of insoluble detritis,
blood, etc., is indicated by the test.

Slack's test. Slack (26) modified the Stewart method by
using tubes of a larger bore containing 2 cc., and smeared the
sediment over 4 square centimeters. He further lowered the
standard to 50 cells or over per one-twelfth oil immersion field,
as warranting the condemnation of milk. When streptococci
are found in the sediment, he condemns for them alone if these
three conditions are fulfilled :

1. Microscopic examination of sediment shows streptococci,
diplococci, or cocci.

, TESTS FOR CELLULAR CONTENT OF MILK. 129

2. A plate culture shows colonies resembling those of strep-
tococci, in excess of 100,000 per cc.

3. From ten to fifty of the colonies are transferred to broth
and grown 24 hours at 37 °C. after which the broth cultures
show streptococci alone or in great excess of other bacteria
present.

Slack utilizes the test also for the direct microscopic esti-
mation of the number of bacteria present.

Doane- Buckley test. Doane and Buckley (10) have devised
a test which has been somewhat improved upon by Russell and
Hoffmann (8). The technic given below is that described by
the latter writers :

COLLECTION OF SAMPLE.

Sample for analysis should be taken from the entire milking of the
animal, as the stoppings contain a somewhat larger number of cells than
other portions of the milk. For the purpose of examination take 200 cc.
in stoppered bottle.

TIME INTERVAL, BETWEEN COLLECTION AND ANALYSIS.

To secure satisfactory results, milk must be examined in a sweet con-
dition. Development of acidity tends to precipitate casein in the milk,
and thus obscure the examination of microscopical preparations. Sam-
ples received from a distance can be preserved for satisfactory microscop-
ical examination by the addition of formalin at time of collection, —
proportion of 1 cc. to 250 cc. of milk. Formalin has been found the best
preservative to use, although it causes contraction of the cells to some
extent.

PROCEDURE WITH REFERENCE TO PREPARATION OF SAMPLE.

1. HEATING SAMPLE.

To secure the complete sedimentation of the cellular elements in the
milk, it is necessary to heat the same to a temperature which will break
down the fat globule clusters, or lessen the ordinary creaming properties
of the milk. Samples should be heated at 65° to 70° C. for not less than
ten minutes, or from 80° to 85° where very short periods of exposure
(one minute) are given. This treatment causes the more homogeneous
distribution of the fat globules through the milk, and when the sample
is then subjected to centrifugal force the cell elements are not caught in
the rising fat globules, but on account of their higher specific gravity are
concentrated in the sediment by centrifugal force.

130 MICROSCOPIC TESTS OF MILK.

2. CONCENTRATION OF CEI,U*LAR KI.KMKNTS.

Ten cc. of milk are placed in an ordinary sedimentation tube, and after
heating as above directed, and subsequently shaking, the milk is centri-
fugalized twenty minutes at 1,200 revolutions per minute. A hand
centrifuge may be employed for this purpose, but where available a steam
turbine Babcock milk tester may be found more practicable.

Note. — This speed, maintained for the time mentioned, is sufficient to
sediment practically all the cell elements suspended in the milk. In our
experience we have found the number of cells in supernatant milk to
average only 3)4 per cent.

3. PREPARING THE SAMPLE FOR EXAMINATION.

After centrifugalizing, the cream and the supernatant milk are removed,
with the exception of the last half cc. by aspirating with an exhaust pump
and wiping the walls of the tube' with a cotton swab. After thoroughly
mixing the sediment with a glass rod, enough of the emulsion is placed
in an ordinary blood counter (Thoma-Zeiss pattern) to fill exactly the
cell. The preparation is then allowed to stand for a minute or two to
permit the cellular elements to settle to the bottom of the cell, while the
few fat globules in the liquid rise to the surface. This method permits
of the differentiation of the cells from the small fat globules, so that a
distinct microscopic observation can be made.

EXAMINATION OF MATERIAL.

The preparation is examined in an unstained condition.

NOTE. — Most observers have usually stained the sediment prior to ex-
amination, but we have found with the above treatment that the cells
may be enumerated quite as well in an unstained as a stained condition.

The count is made wTith a 1-inch eve-piece and | objective. Where the
number of cell elements exceeds 12 or 15 per microscopic field, above
referred to, one-fourth of the entire ruled area of the counter, equivalent
to 100 of the smallest squares of the cell, are counted. Where the cell
elements are less abundant, one-half of the cells in the entire area (two
to four hundred squares) are enumerated. The average number of the
cells per smallest square is then obtained, which, when multiplied by
200,000, gives the number of cells per cubic centimeter in the original
milk. (If multiplied by 4, 000, 000, we have the number of cells per cubic
centimeter in the sediment examined. As the sediment represents the
concentration of the cells into one-twentieth of the original volume of
milk taken, 10 cc. to one-half cc., this number should be divided by 20
to give the number of cells per cubic centimeter in the original milk.)

NOTE. — The above factor of 4, 000, 000 is obtained as follows: The cubic
content of the blood counter represents one-tenth of a cubic centimeter.
This volume is divided by means of the ruled scale into 400 small cubes,
each equal to one four-thousandth of a cubic millimeter, or one four-
millionth of a cubic centimeter.

TKSTS I.'OK CKI,UTI,AR COXTKNT OT MILK. 131

All results should he expressed in nunihers of cells per cubic centime-
ter of the original milk, and 'in order to avoid fictitious accuracy, should
he given in accordance with the method adopted hy the Committee on
Standard Methods of Water Analysis, as reported in this Committee's
report to the Laboratory vSection of the American Public Health Associa-
tion for 1905, page 94.

The test has been shown to give results, on duplicate deter-
minations, with a percentage variation of only about 6% (23).
Thus we have a test of excellent precision that already has
added valuable facts to the knowledge of the subject of leu-
cocytes in milk.

The test has not been widely applied in practice, because of
the difficulty in formulating a standard. A cellular content
varying from 100,000 to 400,000 per cc. is common in normal
cows, and even counts of 1,000,000 per cc. are encountered.
A series of determinations of the leucocytes in the milk of 102
healthy cows showed an average of 241,000 per cc. This
range of counts considerably overlaps the range of counts ex-
hibited by cows with noticeable udder trouble.

Under the circumstances, the milk of a diseased cow with a
count of a few millions is so diluted in the milk of the healthy
cows showing relatively high counts, that the leucocyte con-
tent of the mixed milk is not raised.

Savage s test. Savage (25) has developed a very similar test.
One cc. of milk is diluted with 20 cc. of Toisson's fluid and
centrifugalized for ten minutes at about 1,800 revolutions per
minute. The cream is then agitated with a glass rod and the
whole again centrifugalized for ten minutes, and the super-
natant fluid is drawn off to the 1 cc. mark. The remaining
1 cc. is thoroughly mixed and the number of leucocytes deter-
mined by the use of the Thoma-Zeiss blood counter. This,
like the Doane-Buckley test, shows high numbers of leucocytes,
and the same difficulties in setting a standard are encountered.

Trommsdorjf s test. Trommsdorff (22, 30, 31) arrives at con-
clusions regarding the number of cells in milk by measuring the
amount of sediment obtained by centrifugalizing. Five cc. of
mixed milk is centrifugalized for some minutes at 1,200 revolu-

132 MICROSCOPIC TEvSTS OF MILK.-

tions, and the amount of sediment is noted. For this purpose
there is used a special centrifuge tube with the bottom drawn
out into a capillary tube, properly graduated. These tubes are
prepared by Franz Hugershoff, Leipzig.

The mixed milk of cows with sound udders, as a rule, shows
sediment varying from traces to .5 cc. per liter, with 1 cc.
per liter as the maximum. On the basis of the examination
of hundreds of mixed milk samples, it is asserted that when
the test gives over 1 vol. per mille, it can be shown that one
or more quarters of the udders of the cows are giving milk
with an excessive number of cells.

The test is recommended by Trommsdorff as an aid in the
diagnosis of chronic mammitis. He applied it to the individ-
ual cows in a dairy of good reputation producing milk for
infant feeding. On three different occasions within a period
of four months, he designated as diseased 20 f/c on first test,
34.2% the second, and 27% on the third examination. The
number of co\vs tested on the three occasions varied from 35
to 38. In another dairy of 66, 12% were considered diseased;
in another of 75, 4%; and in another of 82 cows, 19.5'/v .

The test is said to give identical results from duplicate de-
terminations. The criticism has been made that it is a meas-
ure not merely of leucocytes, but also of all substances that
might be centrifugalized down into a sediment.

Significance of results. There has been a wide variation in
the amount of importance that has been attached to the results
of these tests. In some cases their tentative nature has been
very properly recognized and the results used as indication of
the desirability of an examination of the udders of the cow\s.

But instances are not rare of cases where the milk of a dealer
has been publicly condemned on the ground of its containing
pus, staphylococci and streptococci. There are instances, too,
where the tests have been applied to the individual cows of
dairies. Excessive and unreasonable numbers of cows have
been condemned on the basis of the results \vhere no symptoms
of mammitis have been present. The condemnation of the
' majority of the cattle in a herd certainly focusses attention
upon the evidence warranting such a procedure.

SIGNIFICANCE OK RESULTS. 133

The study of the subject has proceeded in the wrong order.
The abnormal has been studied, tests devised and standards
set, all from that standpoint. The use of checks to prove the
value of tests has been too frequently disregarded. For in-
stance, tests have been advocated as of value in detecting the
location of diseased animals, without evidence being brought
forward to show that the test has been tried on a group of
animals known to be diseased. The detection of diseased ani-
mals in the herds supplying condemned milk has been accepted
as confirmation of the value of a test.

The work has resulted in directing attention to the normal,
which has often been too little considered. At present, the
matter is in that period of development in which the fairness
of standards and the accuracy of tests are being scrutinized.
In judging the merits of the various tests, a number of facts
concerning the normal must be considered.

Streptococci in milk Examination of samples of market milk
will show streptococci in a very large percentage of the cases
(13, 14, 15, 16, 19). Heinemann has asserted that "Bacillus
acidi lactici is a myth," and that the common organism sour-
ing milk should be called Streptococcus lacticus.

Reference has already been made in Chap. I to the fact that
an apparently healthy cow was found to harbor a pathogenic
streptococcus in the udder for a considerable period of time.
In consequence the animal might well be called a streptococ-
cus carrier (21).

There are no generally accepted methods for differentiating
the various species of the genus streptococcus found in milk.
It cannot at present be determined whether a given strepto-
coccus is of human or animal origin, virulent or not, or whether
it is a saprophyte. Hemolysis and agglutination have both
failed to yield conclusive results (12) . This group has been the
despair of the systematists. Winslow and Winslow (33) give
a valuable chapter upon streptococci.

Least of all, is it possible to make a differentiation on mor-
phological grounds alone. Our ideas of the hygienic signifi-
cance of the presence of streptococci, based on their rare
discovery by certain tests, must be revised.

134

MICROSCOPIC TESTS OF MILK.

Micrococci in milk. Micrococci (staphylococci) , indistin-
guishable from Micrococcus fjyogcucs, varieties aurcus and albus,
are normal inhabitants of the udder. Consequently, they are
almost the characteristic organisms in the bacterial flora of
fresh milk. Their close relationship to M. pyogencs aurcus
has been determined by thorough systematic study. They
have been reported under this name by numerous observers,
as noted in Chap. I.

The practice of reporting on the presence of pyogenic micro-
cocci in centrifugalized sediments, from microscopic examin-
ation, is certainly not justified.

Leucocytes in milk. Polymorphonuclear leucocytes may be
demonstrated in the milk of any cow and must be regarded as
a normal constituent of milk. As many as 200,000 per cc. in
the milk of a cow may be considered common, and 500,000
per cc. not at all unusual. Sprague (9, 27) found the greatest

Fig. 15 . Section of udder shoeing epithelial celts.

a. Epithelial cell 7chich has become loosened from the duct and is ready
to be carried out. b. Secreting epithelial cell in ica/l of duct . a and b
are of the same structure.

SIGNIFICANCE OF RESULTS. 135

Fig. 16. Section of udder showing epithelial cells and polvnnclear
leucocytes.

a . /-'.pit he! ia I ce!! which has become loosened from the wall of the duct,
similar to a in Fig. 15 . b. Secreting epithelial cell in situ, being same
in st nt dii re as a. c. Polynuclear leucocytes in ducts ready to be thrown
out along with the loose epithelial cells.

variation among the cows of a herd examined by him. Some
of the apparently healthy cows gave counts exceeding 500,000
per cc. It was not possible, however, to pick ten cows that
would average more than that number. The leucocyte count
of the milk of two apparently healthy cows was determined
twice a day over a long period of time, and the most abrupt
fluctuations were observed in the number of leucocytes present.
Heated milk gives a much higher leucocyte count by both
the Doane-Buckley and the smeared-sediment method (9).
Leucocytes and pus cells are identical, although common
practice has determined that, under conditions of health, the
cells in question shall be called leucocytes, and pus cells in
certain pathological conditions. We have no satisfactory
standard at present to determine when this change in designa-

136 MICROSCOPIC TESTS OF MILK.

tion shall occur in the case of cells in milk. It has been sug-
gested that this should be governed by the presence of strep-
tococci, or fibrin, or red blood corpuscles with the cells in
centrifugalized sediments. Besides the polymorphonuclears,
there may be demonstrated in milk sediments large and small
mononuclears and eosinophiles. Our knowledge of the source
of these cells is incomplete as yet. Boynton and Russell inde-
pendently have photographed sections of the functional, healthy
udder, and by this means have shown the presence of leuco-
cytes and other cells in the lumina of the lactiferous ducts in
contact with the epithelium. Those by Boynton appear in
Figs. 15 and 16. Very likely in connection with milk secretion
epithelial debris is extruded in milk, even though the present
trend of opinion denies that fat secretion is accomplished by
fatty degeneration with the destruction of the cell (l, 2).
The general leucocyte content of the blood of the cow seems to
bear no relation to the leucocyte count of the milk (8).

The centrifugalized sediment of milk has been known since
the advent of the cream separator under the name of separator
slime. The mass always collecting in the bowl of the separator
has a disgusting appearance suggesting pus. On this account
soriie dealers clarify their milk, that is, run it through a separator
to remove this sediment and particles of foreign material. Here
again is a case where a normal milk constituent has had its
sanitary significance overrated, because defective tests ordi-
narily showed it to be present in small quantity.

Summary. Mammitis is very common among cows. The
majority of dairies contain cows that show active inflamma-
tory changes in the udder, or evidence of previous manifesta-
tions in the shape of indurations which might warrant the diag-
nosis of chronic mammitis. The discovery of diseased udders
in a herd after the condemnation of the mixed milk by some
test is therefore a fact of questionable significance in proving
the value of the test.

In view of all these circumstances, it cannot be said that
the matter of microscopic tests for cells in milk is yet on a
satisfactory basis. Future work must be done on individual
cows in determining the border line between health and disease.

SUMMARY. 137

It would be well to study the milk of individual cows, prefer-
ably with known histories, with reference to the occurrence of
leucocytes and streptococci. For leucocytes the Doane- Buck-
ley test might be used, and for streptococci, numerical deter-
minations. Histological examination of the udder may prove
to be a reliable criterion for the determination of disease in
experimental work.

The situation is very well summed up in the Preliminary
Statement by the Committee on Standard Methods of Bacterial
Milk Analysis to the Laboratory Section of the American Pub-
lic Health Association, in these words :

"Since, however, evidence already collected, warrants beyond all
question the general statement that these cells frequently do not have the
significance that has been attached to them by many observers, it would
perhaps be more fair to all parties concerned to use this (leucocyte) test
at present as a means of detection only, and not to condemn the supply
unless physical lesions are demonstrated. The standards so far

chosen have been more or less arbitrarily selected on what appears as
rather inadequate data, and from a comparison of results it is apparent
that much more comparative work needs to be done." (8)

The committee expresses* a similar view in its 1908 report as
follows :

' ' It is the opinion of the Committee that milks having high leucocyte
content, unless accompanied by other indications of inflammation such
as blood or virulent organisms, should not be condemned as unfit for use
on the laboratory findings alone. Such milks may be regarded with sus-
picion and the laboratory findings may well serve as a guide for veteri-
nary inspection. " (9)

The writer rather doubts whether microscopic examination
of milk will eventually prove a satisfactory means of protect-
ing the public from streptococci in milk from diseased cows.
When a satisfactory decision has been reached as to wrhat con-
stitutes a diseased udder in a cow and how to detect the pres-
ence in a herd of animals so affected, there remain administrative
difficulties. The individuals in a dairy herd are constantly
changing and the health of the udder is liable to variation from
day to day, which necessitates very frequent examinations.
Then there remains the difficulty of enforcing the exclusion of
the milk of the condemned cow. A large American city of to-

138 MICROSCOPIC TESTS OF MILK.

day is indeed fortunate if it has a corps of inspectors sufficient
to permit visiting each dairy four times a year. The conditions
existing and the difficulties of correcting them by inspection,
lead one to doubt whether anything but pasteurization can
give effective protection from streptococci.

Bloody milk. Slight injuries to the udder will sometimes
cause the rupture of a blood vessel and result in the mixing of
blood with the milk. The blood may be so small in amount
as to escape notice by the milker. After delivery, when the
cream rises, it will be distinctly pink. Microscopic examina-
tion of the cream will reveal red blood corpuscles. To detect
the source of such milk, it maybe necessary to collect a sample
from each quarter of each cow's udder, in separate test tubes.
The bloody sample may be detected in the test, tube immedi-
ately after drawing, or certainly later after the cream has risen.

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140 MICROSCOPIC TESTS OF MILK.

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26. SLACK. Methods of bacteriological examination of milk. Jour.
Infect. Diseases, Supp. No. 2, February, 1906, p. 214.

27. SPRAGUE. The leucocyte content of milk, /in I. I 7. State Hoard
of Health, Vol. IX. No. 1. 1908, p. 44.

28. STEWART. Methods employed in the examination of milk by city
authorities. Amcr. J/«/., Vol. IX, 1905, No. 12, p. 486.

29. STOKES. The microscopic examination of milk. Ann. Kept.
Health Dept. Baltimore, 1897, p. 105.

30. TROMMSDORFF. Munchen. Jfed. II 'chnschr,, 1906, No. 12, S. 541.

31. TROMMSDORFF. Xeue Methode /.ur Diagnose der chronischen,
speziell der Streptokokenmastitis der Kuh. Berlin Tierarztl. \Vchnschr.,
1906, Xo. 15, S. 281.

32. WARD, HENDERSON and HARING. The numerical determination
of leucocytes in milk. Nineteenth Biennial Kept . Cal. State Bd. Health,
1906, p. 142.

33. WINSLOW and WIN-SLOW. The systematic relationships of the
coccaceae. Xew York : John Wiley and Sons. 1908.

34. ZSCHOKKE, transl. by WARD. Experiments in treating infectious

mammitis in the cow. Am. I'et. Rei'., Vol. XXV, 1901, Xo. 1, p. 9.

CHAPTER VIII.

BACTERIOLOGICAL EXAMINATION OF MILK.

Numerical determination of bacteria. The diversity of
methods in use in different laboratories is such that compari-
son of the numerical results obtained by them is quite out of
the question. The water bacteriologists long ago recognized
the undesirability of a diversity of methods in counting bac-
teria in water, and applied a remedy. The standard methods
of water analysis suggested by the committee of the American
Public Health Association have been favorably received. The
results warrant and encourage further work towards the unifi-
cation of other laboratory methods. A committee of the Lab-
oratory Section of the American Public Health Association
has in hand the task of formulating standard methods of bac-
terial milk analysis. The committee, consisting of F. H. Slack,
chairman ; W. H. Park, E. C. Levy, F. C. Harrison, C. E.
Marshall and H. Iv. Russell, has been at work for two years,
weighing the merits of the various methods in use. There
have been submitted two preliminary reports, one in 1907 and
one in 1908 (3, 4). The methods reported are not definitely
selected as a final standard, but represent a consensus of opinion
of American workers on the subject. The methods for the
numerical determination of bacteria herewith recommended
are a composite of the two reports of the A. P. H. A. Com-
mittee. The recommendations are substantially as made in
the 1907 report, and the modifications made in 1908 are intro-
duced and so indicated.

NUMERICAL DETERMINATION OF BACTERIA.

There is no method known by which the exact number of bacteria
in a sample of milk may be determined, and even when the best methods

142 HACTKKIOI.OC1ICAI. EXAMINATION OF MILK.

are used, the count is always less than the actual number of bacteria
present, for the following reasons :

(«) Many bacteria in process of multiplication are held together bv
aclhesive membranes in pairs, chains or masses. It is for the purpose of
separating bacteria thus joined, as well as to obtain an even mixture,
that the sample itself and the diluted sample when plating are shaken.
This shaking, while it breaks up larger masses and shortens long chains,
does not to any great extent break apart the shorter chains, diplococci,
etc. Each of these groups of bacteria, when caught in the solid medium,
develops as a single colony.

(£) It is impossible to obtain a medium suited to the food require-
.ments of all species or races of bacteria (2). (See foot-note.)

It has been found by experiment that a medium consisting chiefly
of a watery extract of raw meat, alkaline to litmus and slightly acid to
phenolphthalein, will furnish the best food for the greatest number (3).

(c} These varying forms of minute vegetable life require varying
temperatures for their best development. Many forms which will de-
velop at room temperature will not grow at bod}' temperature. Some
require a very high temperature for their best growth.

(d) Some bacteria develop in an atmosphere free from oxygen,
some only where oxygen is present ; many are facultative growing under
either condition. Bacteria which require an oxygen -free atmosphere do
not develop in plates as generally prepared. Bacteria requiring oxygen,
if deep in the medium, develop but slowly, as they obtain oxygen only
by diffusion.

• (e) Many forms are slow in developing into visible colonies, some
requiring three or four days. On the other hand, in plates grown for
several days many small colonies are obscured in the growth of larger
ones (4).

(/) Each bacterium requires a certain amount of nourishment for
development (5). There are also antagonistic forms which will not
develop in close proximity to each other. ' It therefore follows that in a
crowded plate, i. e., over two hundred colonies, many will not develop
(6). This is easily proven by making a higher dilution.

Of) Spreaders and molds, by their rapid surface growth, merge with
other surface colonies and obscure deeper ones.

(#) Samples kept in the collecting case at 34° F. for varying periods
have shown a tendency to decrease in the number of bacteria which will
develop into colonies (7). Samples kept in dilution water for several
hours have shown a marked decrease in the number of bacteria which
will develop into colonies (8).

( )n account of these reasons strict adherence to standard procedure is
of especial importance, since there are so many points where disagree-
ment may result if uniform technique is not followed.

NOTK. — The reference numbers occurring in the Committee report refer to the bibli-
ography accompanying the same, appearing on puye I5n.

Xr:\IKRIC.\I, DKTKRMINATIOX OF BACTKKIA. 143

Since at best only approximate results can be reached in the numerical
determination of bacteria in milk, and since from the varying methods
in use at present counts from different -workers are usually incomparable,
those methods which have given best results as a whole should be united
ui)on and adopted by all, that a bacterial count on a sample of milk may
mean the same if made in any standard laboratory.

.CoijvKCTioN OF SAMPLES.

(Quantity of milk required for analysis. The minimum quantity of
milk necessary for making an ordinary bacteriological examination is ten
cubic centimeters. When making" examinations for certified milk, if
possible a pint or quart bottle should be taken and brought to the labor-
atory unopened.

Collecting apparatus. In collecting milk samples for bacteriological
examination it is essential that the sample be taken and kept in such a
manner as to prevent either any addition of bacteria from without or
multiplication of the bacteria originally present (9>. Bottles, tubes,
pipettes, etc., used in the collection of samples, besides being washed,
shall be sterilized with dry heat for an hour at or about 160° C., or to the
charring point of cotton.

In the selection of "certified milk " samples it is recommended wher-
ever possible that an unopened bottle be taken, placed in a suitably iced
case and brought at once to the laboratory.

vSamples of "market milk" may be collected as are water samples,
in sterile, wide-mouthed, glass-stoppered four-ounce bottles ; the case in
which they are carried being well iced (10). The principal difficulty
encountered in this method is in transferring the sample from the origi-
nal container to the bottle, and the various string and wire devices by
means of which the bottle is immersed in the original container are
objectionable both on account of the labor of preparing such an outfit
and also on account of the coating of milk left on the outside of the
bottle when the sample has been taken.

An apparatus designed for the use of thirty-two test tubes as containers
(11.) is recommended as superior to one designed for bottles.

It has been proven that with samples kept properly iced in this par-
ticular form of case there is no increase of bacterial content even for
twenty-four hours, but rather a slight decrease (7), the counts varying
hardly more than might be expected in duplicate plates. It is recom-
mended, however, that examination of the samples be proceeded with as
quickh- as possible after the collections are made.

Identification of samples. When bottles are used identification num-
bers should be etched on both bottle and stopper. Test tubes .should be
labeled or etched (12) and numbered.

A complete record of the samples taken, giving date, time, place,
name of party from which sample 'is taken, name of collector, tempera-

144 BACTERIOLOGICAL EXAMINATION OK MILK.

ture of milk, character of original container (tank, can, lx>ttle), etc.,
should be written opposite duplicate numbers in a blank book or pocket
card catalogue, or this information ma}- be written on small tags and
tied or wired to the corresponding test tuBe or bottle.

Temperature. The temperature should be taken immediately after
taking the sample for analysis, while the milk is still thoroughly mixed.

If it is desired to take the temperature of "certified milk," this should
be done wyhen the sample is taken, but from another bottle.

A floating thermometer, graduated to the Fahrenheit scale, is most
convenient, and the temperature should be expressed to the nearest
degree. It is necessary to standardize the thermometer for at least ten
degrees on each side of the legal temperature limit. A quickly regis-
tering thermometer should be left at least one minute in the milk and
read as soon as removed. A small piece of clean absorbent cotton may
be used to wipe the adhering milk from the thermometer that the scale
may be easily seen.

Representative samples. The collector should always select his own
sample, and care should be taken to secure a sample which is truly rep-
resentative of the milk to be examined.

One of several methods of mixing the milk may be used, comparison
having shown the results to be practically the same (9).

1. Pouring the milk into a sterile receptacle and back.

2. Shaking the milk thoroughly with receptacle turned upside down.
(This may be done where the can or bottle is tightly stoppered or capped
and is not so full as to prevent thorough agitation. )

3. In open tanks in stores it is allowable to stir thoroughly with the
long-handled dipper generally found in use.

4. Where the test tube collecting case is used, thoroughly reliable
results are secured by first shaking the can or bottle ; and, second, stir-
ring with the large pipette before taking the sample, care being taken to
close the upper end of the pipette with the finger so that no milk enters
until after the mixing, or the pipette may be emptied after stirring before
the sample is taken.

5. For certified milk samples it is recommended that, on arrival at
the laboratory, the bottle be opened with aseptic precautions and the
milk thoroughly mixed by pouring back and forth between the original
bottle and a sterile bottle. Another method is to mix as thoroughly as
possible by agitation for five minutes, then burn through the paste-board
stopper with a- hot iron and remove the desired amount of milk with a
sterile pipette (13).

The interval between collection and analysis. Generally speaking the
shorter the time between the collection and examination of milk samples
the more accurate will be the results. For routine work the attempt
should be made to plate within four hours of the time of collection.

Too much stress cannot be laid on keeping the samples properly iced

NUMERICAL DKTKRMIXATIOX OF HACTKRIA. 145

during tliis interval. They should be kept below 40° F., but care should
be taken that the}' are not frozen.

DILUTIONS.

Ordinary potable water, sterili/.ed, may be used for dilutions. Occa-
sionally spore forms are found in such water which resist ordinary auto-
clave sterilization ; in such cases distilled water may be used or the
autoclave pressure increased. With dilution water in eight-ounce bottles
calibrated for ninety-nine cubic centimeters all the necessary dilutions
can be made.

Short, wide-mouthed ' ' Blakes ' ' or wide-mouthed French square bottles
are more easily handled and more economical of space than other forms
of bottles or flasks ( 11 ).

Eight-ounce bottles are the best, as the required amount of dilution
water only about half fills them, leaving room for shaking. Ivong-fiber,
non-absorbent cotton should be used for plugs. It is well to use care in
selecting cotton for this purpose to avoid short-fiber or "dusty cotton,"
which gives a cloud of lint-like particles on shaking. Bottles and tubes
should be filled a little over the 99 cc. and 9 cc. marks to allowr for loss
during sterilization (14).

The dilutions recommended are 1-10, 1-100, 1-1,000, 1-10,000, 1-100,-
000 and 1-1,000,000.

For certified milk the 1-10 and 1-100 dilutions should be used, while
the 1-10,000 will usually be found best for market milk.

The 1-10 dilution is prepared by shaking the milk sample twenty-five
times and then transferring 1 cc. of the milk to a test tube containing 9
cc. of sterile wrater.

The 1-100 dilution is prepared in the same way, except that a bottle
with 99 cc. of sterile water is substituted for the test tube.

The 1-1,000 dilution is prepared by first making the 1-100 dilution,
shaking twenty-five times and transferring 1 cc. of the dilution to a test
tube containing 9 cc. of sterile water.

It is recommended that that dilution be used which will produce
about two hundred colonies to a plate, ranging from 40 to 400 ; where a
1-10 dilution exceeds this number the 1-100 dilution is more accurate, etc.
The number of bacteria present may if desired be approximately esti-
mated before dilutions are made by direct microscopic examination of a
properly prepared sediment. Otherwise it is necessary to make a range
of dilutions, thereafter selecting for record the count obtained on that
plate which yields between 40 and 400 colonies.

Plating whole milk is unreliable (15), whatever qualities be used,
since the bacteria are not so well separated as in the dilutions, and often,
owTing to the crowded conditions, only a portion of the bacteria present
will develop into visible colonies (6). Moreover, if a cubic centimeter
of the milk is used, the turbidity of the jelly, due to the presence of the
milk, hides the colonies present from the eye.

146 BACTERIOLOGICAL EXAMINATION OF MILK.

MEDIA.

The standard medium for determining the number of bacteria in milk
shall for the present be agar, made according to the recommendations of
the Committee on Water Analysis (1), except that the percentage of
agar shall be 1 per cent, and the reaction -; 1.5 (2d).

All variations from agar media made as described shall be considered
as special media.

Much work yet remains to be done on media ; the above is recom-
mended as giving the highest and most uniform counts as far as our com-
parative work has extended and with but slight variations is the medium
in most common use.

Storage of media. Media may be made up in quantity, tubed and
stored (preferably in an ice chamber).

PivATixr,.

Plating apparatus (11). For plating it is best to have a single water
bath in which to melt the media and a water-jackettd water bath for
keeping it at the proper temperature ; a wire rack, which should fit both
of the water baths, for holding the media tubes ; a thermometer for
recording the temperature of the water in the water-jacketed bath ; ster-
ile 1 cc. pipettes ; sterile petri dishes ; and sterile dilution water in
measured quantities.

For milk work porous earthenware petri dish covers (16), are much
superior to glass covers, .since they absorb the excess moisture from the
agar and prevent "spreading."

It is quite essential to the best results that the porous covers should
be wet as seldom as possible. In sterilizing them the process should be
prolonged over the time necessary to kill the organisms in order that
the covers ma}- be thoroughly dry.

Extract from the 1908 report. A method of avoiding the troubles due
to moisture consists of inverting the plates, and putting in the lid of
each petri dish, a strip of blotting paper on which there is a large drop
of glycerine. Incubate as directed.

As a result of these experiments we feel that the agar plates with
glycerine, prepared in the manner above indicated, are slightly more
reliable than the earthenware tops.

The principal objections to the latter are :

(1) They scratch the glassware.

(2) The plate has to be uncovered for examination, and

(3) They are more liable to dry out if kept longer than 36 hours.
Straight-sided 1 cc. pipettes are more easily handled than those with

bulbs ; they may be made from ordinary glass tubing about ^ of aw inch
in diameter and calibrated in the laboratory (17). They should be made
about ten inches in length.

NUMERICAL DETERMINATION OF BACTERIA.. 147

riating technique. The agar after melting should be kept in the
water-jacketed water bath between 40° C and 45°C. for at least fifteen
minutes before using, to make sure that the agar itself has reached the
temperature of the surrounding water. If used too warm the heat may
destroy some of the bacteria or retard their growth.

For routine work in cities in order to bring down the actual number
of colonies in a plate around the standard of two hundred, it is well to
use a dilution of 1-10,000. To make this dilution use two bottles of
sterile water each containing 99 cc.

Shake the milk sample twenty-five times, then with a sterile pipette
remove 1 cc., put into the first dilution water and rinse the pipette by
drawing dilution water to the mark and expelling ; this gives a dilution
of 1 to 100.

Shake the first dilution twenty-five times, then with a fresh sterile
pipette remove 1 cc., put into the second dilution water, rinsing the
pipette to the mark as before ; this gives a dilution of 1 to 10,000. Shake
the second dilution twenty-five times, then with a sterile pipette remove
1 cc., and put it into the petri dish, using care to raise the cover only so
far as necessary to insert the end of the pipette.

Taking a tube of agar from the water bath, wipe the water from out-
side of tube with a piece of cloth, remove the plug, pass the mouth of
the tube through the flame, and pour the agar into the plate, using the
same care as before to avoid exposure of the plate contents to the air.

Carefully and thoroughly mix the agar and diluted milk in the petri
dish by a rotary motion, avoiding the formation of air bubbles or slop-
ping the agar, and after allowing the agar to harden for at least fifteen
minutes at room temperature place the dish bottom down in the incuba-
tor. The practice of mixing the diluted milk with the agar in the in he,
leaving a certain portion of the bacteria unplated, is not recommended
by the Committee.

Controls. Plating should always be checked by controls. A blank
plate should be made with each set of milk plates for control of the water,
petri dishes, pipettes, etc.

For control on technique of plating it is recommended that for work
on "market milk," duplicates be made each day on several plates.

" Certified milk" should always be plated in duplicate, and where pos-
sible it is well to have one man's work occasionally checked by another.

Unless duplicate plates show as a rule approximately the same count,
the worker should see if there is error in his technique.

Racks are very useful for stacking the plates and to prevent breakage.

Plating should be done always in a place free from dust or currents
of air.

In order that the colonies may have sufficient food for proper develop-
ment, 10 cc. of agar shall be used for each plate. In plating a large
number of samples at one time the dilution and transfer of diluted milk

148 BACTERIOLOGICAL EXAMINATION OF MILK.

to the plates may be done for four or eight samples, then the agar
poured, one tube to each plate, then another eight samples diluted, etc.

INCUBATION.

Methods. Concerning incubation two methods are at present in use.
Three-fifths of the laboratory workers consulted recommended incuba-
tion at 37° C. for twenty-four hours with saturated atmosphere, the
remaining two- fifths allowed varying lengths of time at different degrees
of room temperature and at whatever degree of humidity happened to
obtain.

When considering these two methods many ad vantages. of the method
of incubation at 37° C. are evident, including the ease of maintaining
this temperature in any laboratory, the evident uniformity of counts so
obtained in different places as compared with those obtained by the
varying methods of technique, as to temperature, and incubation period,
where room temperature is employed, and the quickness with which
results are obtained, doing away with large accumulations of uncounted
plates.

Forty-eight hour plates grown at 37° C. give a slightly higher count
(11), not enough higher to materially change the report, while the loss
by "spreaders" is increased and the count delayed.

To secure saturation of the atmosphere the incubator should be made
with a shallow depression over the whole bottom surface, which may be
kept filled with water, or in default of this a large shallow pan of water
may be kept on one of the lower shelves.

Much work will be done on comparison of 37° C. and ' ' room temper-
ature " during the coming year.

Extract from 1908 report. Summarizing up the work on incubation,
we ma}- say that the weight of evidence is against 24 hours incubation at
37° C. and two day incubation at or around 21° C., the number of col-
onies obtained being too small for a fair idea of the number of bacteria
in the sample.

Bight day and ten day incubations at 21° C., while giving a slightly
higher average count, have disadvantages, such as delay in reports,
accumulation of plates and drying out of media, which render them
undesirable for routine work.

The lines of highest efficiency on a working basis would seem to rest
on a 48 hour incubation at 37° C. and a five day incubation at 21° C.

It would seem advisable to recognize as standard both of these
methods of incubation (it being understood that carefully regulated
incubators should be used).

Board of Health regulations governing the number of bacteria allow-
able in milk, should state the method to be used in examination and in
all reports, papers, etc. , on the bacterial count of milk this factor should
be explicitly stated.

NUMERICAL DETERMINATION OF BACTERIA.

149

COUNTING.

Expression oj results. Since minor differences in milk counts are
within the working error of the methods and are of no significance in
practice, the following scale has been adopted for recording results of
market milk examinations :

Counts below 100,000 are distinguished by ten thousands.

Counts between 100,000 and 500,000 are distinguished by fifty thou-
sands.

Counts between 500,000 aud 1,000,000 are distinguished by hundred
thousands.

Counts between 1,000,000 and 2,000,000 are distinguished by two hun-
dred thousands.

Counts between 2, 000, 000 and 5,000,000 are distinguished by five hun-
dred thousands. .

Counts above 5,000,000 are distinguished by millions.

Therefore only the following figures are used in reporting :

Below 10,000 Above
Above 10,000

20,000

30,000

40,000

50,000

60,000

70,000

80,000

90,000
" 100,000
" 150,000
" 200,000

Counts on ' ' certified " or " inspected ' ' milk shall be expressed as
closely as the dilution factor will allow.

The whole number of colonies on the plate shall be counted, the prac-
tice of counting a fractional part being resorted to only in case of neces-
sity, such as partial spreading.

Various counting devices have been recommended by different work-
ers. The more simple ones, where the whole plate can be seen at once,
are more desirable on account of there being less likelihood of recount-
ing colonies. Colonies too small to be seen with the naked eye or with
slight magnification shall not be considered in the count.

250,000

Above 1,400,000

300,000

" 1,600,000

350,000

" 1,800,000

400,000

" 2,000,000

450,000

11 2,500,000

500,000

" 3,000,000

600,000

11 3,500,000

700,000

" 4,000,000

800,000

" 4,500,000

900,000

" 5,000,000

1,000,000

6,000,000

1,200,000

etc.. by millions

150 BACTERIOLOGICAL EXAMINATION OF MILK.

BIBLIOGRAPHY OF COMMITTEE REPORT.

1. Transactions A. P. H. A., Vol. XXX, Part II.

2. Comparison of Media.

a. Heinemann, Appendix A.*

b. Prescott, Appendix B.:;:

c. Prescott, Technology Quarterly, Vol. XVIII, No. 3, page 252.

d. Report Boston Board of Health, 1906, page 74.

3. Fuller and Copeland, Report Massachusetts State Board of Health,
1906, page 585. Muir and Ritchie, 1903, page 37.

4. Slack, Appendix C.*

5. Hill and Rllms, Report of Brooklyn Water Supply, 1897.

6. Hill, the Mathematics of the Bacterial Plate Count ; Paper read
before Laboratory Section A. P. H. A., Sept. 30, 1907.

7. Slack, Appendix D.*

8. Slack, Appendix E.*

9. Report Boston Board of Health, 1906, page 76.

10. Stokes, Appendix F.*

11. Hill and Slack, American Journal of Public Hygiene, November,
1904, page 237.

12. Gorham, Laboratory Course in Bacteriology, page 54.

13. Method used by H. W. Hill, Minnesota State Board of Health
Laboratory.

14. Heinemann, Appendix G.*

15. Campbell, Appendix H.*

16. Hill, Journal of Medical Research, Vol. XIII, No. 1 (New Series,
Vol. VIII, No. 1), pages 93-96, December, 1904.

17. Gage, Appendix I.*

Significance of results. In the interpretation of the results
of the numerical determination of bacteria in milk, it must
be constantly 'borne in mind that the results indicate only con-
ditions at the moment the sample was taken. We are not
dealing with the quantitative estimate of a milk constituent
like fat, which is present in the same proportion in .a given
sample a't all times. It must be remembered that a bacterial
count is a measure of the progress of multiplication of a com-
plex mixture of micro-organisms, controlled by an equally
complex series of factors. The results at any given time
depend in part upon initial numbers, species, characteristics
of the milk, its age, the temperature at which it has been kept,

* Reference to Appendix of Committee report, to be found in the American Journal
of Public Hyiriene, N. S. Vol. Ill, 1901, No. 5, pp. 354 to 364.

MICROSCOPIC ESTIMATE OF BACTERIA. 151

and the method of making: the determination. Wrong con-
clusions will be reached, if emphasis is laid upon mere num-
bers without a consideration of the other factors.

A numerical determination taken by itself without full
consideration of all the factors involved has no value. Per-
sons not familiar with the circumstances are apt to attempt
to make comparisons when such are inadmissible. The results
of the work of two laboratories cannot be compared, unless
there has been uniformity in every detail that would affect
results. Every bacteriologist doing much milk work has had
embarrassing experiences along this line. The man who has
had the longest experience with numerical determinations of
bacteria in milk in connection with milk commission work
believes that no good end is served by stating results publicly
in numerical terms, and acts in accordance therewith. In any
event, the publication of numerical results should be restricted
to a small circle of persons wrho appreciate their significance.

The bacterial count is undoubtedly the instrument by which
the effectiveness of good dairy methods is measured, and has
been a prominent factor in the development of those methods.
It reveals facts regarding the operation of high grade dairies
that no inspection could disclose. A count of certified milk
is better evidence of the observance of certain features of
cleanliness in handling the milk than a visit to the dairy.

The value of the bacterial count in locating contamination
is recognized by careful dairymen. Some large distributing
firms use the method to good advantage in controlling the
producing dairies. Postal card reports sent from time to time
convince the dairyman that his product is under scrutiny and
stimulate him to greater efforts.

Microscopic estimate of bacteria. Slack has observed that, in
connection with his method for the study of milk sediments,
the number of bacteria may also be roughly estimated. By a
long series of comparative tests, it has been found possible to
tell from the number of bacteria in the smear whether or not
plate cultures would show above or below 500,000 colonies per
cc. An error of less than \(/< was made in this regard. Slack
uses the test to eliminate those samples of milk that are well

152 BACTERIOLOGICAL EXAMINATION OF MILK.

within the limit, and thus saves the trouble of plating them.
The committee of the A. P. H. A. in its 1908 report (4)
makes the following comment :

" Several laboratories are now making this examination as a routine
procedure. One \vorker (Conn), who has done considerable experimen-
tation along this line during the past year sums up his results in attempts
to actually approximate plate counts as follows :

1 The method seems to be fairly satisfactory for milk, the bacterial
content of which is not too low or too high. When the numbers are down
below ten thousand the method seems to be quite inaccurate, and when
the numbers run up into the millions I find also the numbers are not
very reliable. Within the limits of from thirty thousand to three hun-
dred thousand, however, the method seems to be fairly good. I have,
however, had the experience of occasionally finding samples of milk '
which, when tested by direct microscopic methods, gave results very
different from those by the plate method. My general feeling is that a
direct microscopic method might give an idea as to whether the sample
is very good or very bad, but would not replace the plate method of
examination in determining actual numbers and would be of no use for
the examination of samples of milk whose number of bacteria is quite low.'

"Another (Campbell), who has done much work with this method,
finds it chiefly useful as a preliminary test, not. plating samples which
are shown by the microscope to contain less bacteria than the city regu-
lation permits, in those samples which are plated it serves as a guide for
the proper dilutions. He finds it possible with this examination to cor-
• rectly state in nearly every instance \vhen a milk contains less than 50,-
000 bacteria to a cubic centimeter, or when it contains over a million bac-
teria to the cc. On actual estimates within 50,000 of the plate count his
average is 66% correct on counts between 50,000 and 500,000 and 50%
correct on counts between 500,000 and 1,000,000."

The subject of the microscopic examination of milk for leu-
cocytes and streptococci is discussed in Chap. VII.

Tests for B. coli« Methods for the examination of milk for
B. coli are in the process of evolution. The question of the
accuracy and significance of some of these tests has received
some attention by the committee of the A. P. H. A. in its 1908
report. The methods have hardly been tested out sufficiently
to warrant recommendation for general use.

Examinations for typhoid fever and diphtheria bacilli. In
connection with the investigation of milk-borne epidemics of
typhoid fever and diphtheria, the desire is very frequently

~ TUBERCLE BACILIJ. 153

expressed for an examination of the milk with respect to the
presence or absence of the germs of these diseases. The tech-
nical difficulties at present surrounding such work are too
great to render it worth undertaking as a matter of routine.
Then too it is very likely the germs may not be present at the-
time milk is under suspicion, which may be long after the pol-
lution of the milk occurred. The presence of diphtheria bacilli
in milk has been demonstrated by the inoculation of guinea-
pigs with centrifugal sediment and the production of diph-
theria. The relation of milk to these diseases as demonstrated
by other means is discussed in Chap. III.

Tubercle bacilli. The examination of milk for tubercle
bacilli is not recommended as a profitable line for routine work.
Owing to the fact that tubercle bacilli appear in milk inter-
mittently, a negative result is of no significance in showing
the usual quality of the milk in this regard. Nevertheless,
occasions arise when the interest in the result warrants the
trouble taken to secure the information as to the presence of
the tubercle bacilli.

The work described below calls for the use of a large centrif-
ugal machine instead of the ordinary machine used in urine
analysis, but the latter may be employed with the disadvantage
of using the smaller amount of milk. The technic- varies
somewhat with different wrorkers, but that of Anderson (l)
is given here and is also recommended by the A. P. H. A.
committee.

To 50 cc. of well-mixed sample in a sterile centrifuge flask,,
add 100 cc. of sterile distilled water. Centrifugalize at 2,000
revolutions for one hour. Five cc. of the sediment is inocu-
lated into each of at least two guinea-pigs subcutaneously in
the abdomen, using a different syringe for each pig. An
equal number of control pigs are kept with those inoculated,
as a control on health of stock, environment, etc.

Examine for enlarged glands after four weeks and separate
those showing evidence of tuberculosis. Pigs are apt to die
early from acute infections resulting from bacteria in the milk
other than tubercle bacilli. Those alive at two months are
given 2 cc. of crude tuberculin, which kills badly tubercular

154 BACTERIOLOGICAL EXAMINATION OF MILK.

pigs and sickens those with slight lesions. Others, presumably
non-tubercular, are chloroformed. At autopsy, all organs
showing deviations from the normal are examined for tuber-
culosis by smears, cultures and sections.* Care must be taken
to differentiate tuberculosis from the lesions of Bacillus pseudo
tuberculosis. This organism causes peritonitis with adhesions
and nodules in organs like the liver or spleen, which show
a tendency to central necrosis. In section these nodules are
seen to consist of lymphoid elements, very few epithelioid and
multinuclear cells. The giant cells typical of tuberculosis do
not occur. Cultures grow more rapidly than those of //.
tuberculosis.

The older method of direct microscopic examination of milk
sediments for tubercle bacilli is quite inadmissible, and all con-
clusions based upon it have to be discarded. Other organisms
having the staining peculiarities of B. tuberculosis (acid-fast)
are frequently found in dairy products. Johne's disease,
affecting the intestines of cattle, is caused by an organism
similar in morphology to B '. tuberculosis.

Determination of streptococci. Streptococci may be recog-
nized on the plates made in connection with the standard
method for numerical determination. The colony is small,
consisting of a slightly elevated center surrounded by a thin
spreading border. Their significance in a quantitative sense is
discussed in Chap. VII.

Qualitative determinations. The examination of milk by
methods permitting the determination of the percentage of
various groups of organisms has been quite extensively used
in the study of dairy problems, and has yielded valuable
information (2). Certain characteristics of growth on plates,
such as formation of acid, character of colony, and liquefaction
of gelatin, have been made the basis for the identification of
groups of organisms for the' study of their growth under var-
ious conditions. The relative proportion in which certain

* Dead tubercle bacilli, killed for instance «by pasteurization, may lead
to the formation of small tubercles, with no tendency to further multi-
plication. Some workers consider it well to inoculate a second pig from
these lesions, to settle doubt as to their nature.

REFERENCES. 155

groups of organisms are present in milk is of importance. If
is doubtful, however, if the necessity for this information would
warrant the use of the method in the ordinary control work
in connection with municipal milk supplies. Qualitative
examinations are of decided advantage in the examination of
pustL'iiri/.ed milk.

REFERENCES.

NOTK. — The reference numbers in parentheses occurring in the A. P.
H. A. report on pages 141 to 149 refer to the bibliography accompanying
that report on page 150.

1. ANDERSON. The frequency of tubercle bacilli in the market milk
of Washington, 1). C. Bui. No. 41, Hyg. Lab., U. S. Pub. Health and
Mar. Hasp. Serv., Washington, D. C., 1908, p. 163.

2. CONN and ESTKN. Qualitative analysis of bacteria in market milk.
Fifteenth Ann. Kept. Storrs Agr. Exp. Sta., Storrs, Conn., 1903, p. 63.

3. Preliminary Statement by the Committee on Standard Methods of
Bacterial Milk Analysis to the Laboratory Section of the American Pub-
lic Health Association. Amer. Jour. Pub. Hyg., Vol. XVII, 1907, No.
4, N. S. Vol. Ill, No. 5, p. 331.

4. Manuscript report of the same committee for 1908.

CHAPTER IX.

CERTIFIED MILK.

Milk commissions. The medical milk commission move-
ment is the outgrowth of the efforts of one physician to secure
clean milk. Dr. Henry L. Coit of Newark, N. J., recognized
the inadequacy of state and municipal methods of dealing with
the milk problem. He and his associates, in 1893, organized
a professional organization known as the Medical Milk Com-
mission of Essex County, New Jersey. They drew up regu-
lations covering the methods of producing clean milk, quality
of the product, etc. One dairyman, Mr. Stephen Francisco,
agreed to conform to the regulations ; in default of which he
was to forfeit the support of the commission in guaranteeing
his product to the profession.

The object and scope of the work of the commission were
defined as follows (8) :

" The objects of this commission are to establish correct clinical stand-
ards of purity for cows' milk ; to become responsible for a periodical
inspection of the dairies under its patronage ; provide for chemical and
bacteriological examinations of the product, and the frequent scrutiny of
the stock by competent veterinarians ; to promote only professional and
public interests.

' ' The following are three general requirements or standards for the
milk: (1) An absence of large numbers of micro-organisms, and the
entire freedom of the milk from pathogenic varieties ; (2) unvarying
resistance to early fermentative changes in the milk, so that it may be
kept under ordinary conditions without extraordinary care; (3) a con-
stant nutritive value of known chemical composition, and a uniform
relation between the percentage of fats, proteids, and carbohydrates. "

Dr. Coit suggested the use of the phrase " certified milk "
to designate the product turned out under the approval of the
commission. Mr. Francisco, in order to protect the word

certified ' ' from illegitimate u&e by trade competitors, regis-

:\III,K COMMISSIONS. 157

tered it in the Patent Office. The original certified dairy has
prospered and to-day is one of the largest sanitary dairies in
the country. The idea of milk certification spread slowly at
first, but now about forty milk commissions are scattered over
the country (1, 2, 7, 8, 12).

Association of milk commissions. For purposes of mutual
benefit, the various commissions have formed an association
under the name of The American Association of Medical Milk
Commissions. The original purposes of the association are
best defined by Article II of its constitution (l) :

' ' The purpose of this Association shall be to federate and bring into
one compact association the Medical Milk Commissions of the United
States ; to exchange views and to adopt uniform methods of procedure
in the work of the Medical Milk Commission ; to fix chemical and bac-
teriologic standards ; to determine the scope of medical and veterinary
inspections, and to foster and encourage the establishment of Medical
Milk Commissions in other cities."

During the two years of the existence of the association, it
has abundantly fulfilled expectations.

Source of authority . A milk commission should derive its
authority from a regularly constituted medical society by whom
it is appointed and to whom it is responsible. The majority
of the membership should be physicians, and the commission
should be a strictly medical organization with professional
objects for the public good. It is quite a general practice to
appoint a minority of lay members on commissions in order to
afford representation for civic bodies prominently identified
with the clean milk movement. Exceptions as to the appoint-
ing body have occurred in the case of milk commissions ema-
nating from civic bodies. For instance, the pioneer milk com-
mission in California was established by a woman's club. It is
well, however, to adhere to a county medical society as a
source of authority in order to preserve a sharp distinction
between the legitimate and the illegitimate.

Field of milk commission activities. A milk commission is
not designed necessarily to invade the field of ordinary muni-
cipal milk inspection, although some schemes for such milk
inspection recognize milk commission work. The commission

158 CERTIFIED MILK.

sets the necessary high standard for the production of irre-
proachable milk and agrees to certify the milk of as many
dairymen as desire to follow its rules. Only in the larger
cities should a commission expect to enlist a number of dairy-
men. Many commissions have only one dairyman, although
it is rather embarassing to recommend the milk of but one
dealer.

In many cases, a milk commission cannot demand that a
dairyman shall sell only certified milk. The consumers of
this grade of milk are few and widely scattered. Under such
conditions, the expense of delivery of certified milk alone
would be prohibitive. A commission can hardly concern
itself with other business relations of the dealers further than
to refuse certification to a dealer known to sell adulterated milk.

The milk commission reports its findings to the appointing
body, whence announcement of its conclusions is made to the
profession. Announcement is best made by means of a postal
card mailed from month to month.

Agreement with dairymen. The first commission entered
into an elaborate contract with the dairyman, in which every
detail was carefully defined. In other cases, it has been found
sufficient to furnish the dairyman a list of the requirements of
the commission with the information that habitual non-com-
pliance will result in the withdrawal of certification. The
various commissions do not have uniform requirements, but
this may come in time. The purpose to be attained seems to
be a definition of minimum requirements, in order not to deter
the various commissions from frying improvements.

Sanitary requirements for dairymen. § These vary slightly
with different commissions. The following ones, drawn up
by Professor R. A. Pearson, an acknowledged expert on the
matter, \vere adopted at the 1907 meeting of the American
Association of Medical Milk Commissions, and may well be
followed :

LOCATION AND CHARACTER OF LANDS.

"Certified" milk shall be produced only on gxxxl farming land,
which, together with all equipment and methods, is approved by the
Commission.

AC.KKKMKXT WITH DAIRYMEN. 159

Pastures or paddocks to which cows have- access shall he : (1) Free
from marsh or stagnant pool ; (2) Crossed by no stream which might
easily become dangerously contaminated ; (3) At sufficient distance from
offensive conditions to suffer no bad effect from them.

I VOCATION, CONSTRUCTION, LIGHTING, AND VENTILATION OF STABLES
AND OTHER BUILDINGS.

Buildings in which "certified" milk is produced or handled shall be
located where good drainage can be secured and at sufficient distance
from other buildings, dusty roads, cultivated and dusty fields and other
possible .sources of contamination, to avoid excessive dirt, dust, or odors
from such 'places.

The stables shall be constructed so as to favor the comfort of the cows
and the efficiency of labor. The floor shall be of cement or an equally
durable and non-absorbent material, and sloped to provide drainage.
Stall floors may be constructed of sound plank well laid on cement.

The inside surface of the walls and all interior construction shall be
smooth, with tight joints, and capable of shedding water. The ceiling
shall be of smooth material and dust tight. All horizontal and slanting
surfaces which might harbor dust shall be avoided as far as possible.

The stable shall be as well lighted as the average house, and shall
have an average of at least four square feet of window glass for each
animal, with as much sunlight as possible, and the light evenly dis-
tributed.

The ventilation shall be so efficient that one will not notice a stale,
disagreeable, or strong odor on entering the building.

DRAINAGE.

Drainage from buildings shall be carried under ground to a point at
least one hundred feet from any building used for producing or hand-
ling milk, and so far away that odors from the drain openings can not
find entrance to the buildings.

WATER SUPPLY.

There shall be an abundance of pure water from an approved city or
town supply, or from a deep well or deep spring, thoroughly protected
against the entrance of surface water and located not less than one hun-
•dred feet from stable, barnyard, privy, or other possible sources of con-
tamination.

>No other water except that from approved reservoirs or filters shall be
used for cooling milk, cleaning utensils, or otherwise in the dairy house.
The cows may be permitted to drink from a running stream of clear
water.

Examination of water. The water shall be examined by the bacteri-
ologist and chemist at least once each winter and once each summer,

160 CKKTIFII'.l) MII.K.

and ma\ be rejected wheiievrr tin- purity is suspected. Samples of
water tor analysis shall IK- furnished as ofu-n as requested.

R 1-:.M( )\ AI, (>!• \\'ASTK FUOM STA1?I,K.

All waste shall be removed and the stable thoroughly cleaned
throughout at K-ast once daily. When cows an- kept in the stable con-
tinuously, the manure shall IK- re-moved from the stalls at least twuv
daily.

Sl'KROI XniNV.S ()!•' Hril.DINC.S.

Surroundings of all buildings shall be kept clean and in good order.
The accumulation of dirt, rubbish, manure, or decayed matter shall not
be permitted. The stable yard shall be well drained.

ST< >c K .

The- herd shall include no animal that is known to be diseased or that
seems to show evidence of acute, chronic, local, or other disease, unless
permitted by the veterinarian.

'/i'.sV fvr tuht'irnlosis. Tuberculin shall be used in examination for
tuberculosis whenever required by the rules governing veterinary
inspection.

.•Idditions to herd. Animals proposed to be added to the herd shall
be kept in a separate quarantine building, at least two hundred feet
from the stable, and their milk shall not be used until approved by the
veterinarian, after a physical examination and tuberculin test.

Exclusion from herd. Any animal showing evidence of general ill-
health and any that is off-feed shall be at once removed from the stable
and its milk withheld.

So far as possible, the cows shall be grouped or milked in groups, so
that the milk collected in any short period shall show about the same
composition as the average for the herd.

Housing. The cows shall be kept in comfortable and healthful quar-
ters and not unnecessarily exposed to inclement weather.

Foods. All food stuffs shall be kept in an apartment separate from
the cows and used only after milking, and shall not be brought into the
stable except just before being fed.

•Only those feeds shall be used which consist of fresh, palatable, or
nutritious materials, such as are known will not injure the health of the
cows or unfavorably affect the taste or character of the milk.

A well-balanced ration shall be used, and changes of feed shall he-
made slowly.

ll'afcr. Cows shall be given fresh water at least twice daily.

Calving — Exclusion from the herd. Cows shall be removed from tin-
stable in which the herd is kept at least twenty-one days before due to
calve, and not returned until seven days after calving.

AC.KKKMKXT WITH DAIK YMKN. 161

/;" rcvv /\r. Cows shall be- permitted to c-xercist/.

They shall be cleaned, milked, and fed regularlv, and always treated
kindly.

Long hair on the udder and surrounding parts shall be clipped.

PREPARATION OF THF, Co\V FOR MlLKINC,.

Grooming', At least half an hour before milking, the cows shall be

thoroughly cleaned, and compelled to remain standing until milked.

I'^nial cleansing-. Not more than ten minutes before each milking,
the udders and surrounding parts shall be thoroughly cleaned by the
use of moist clean cloths.

THE COLLECTION OF THK MILK ; HOURS OF MILKING; METHODS OF
MILKING; THK USE OF THE MILKING MACHINE.

Fore-milk. The first three or four streams from each teat shall be
drawn into a separate vessel and discarded.

Milking shall be done in a quiet, clean, and thorough manner, and at
regular hours ; as nearly as possible, at twelve-hour intervals.

No person not employed in the stable shall be allowed there during
milking.

The milking machine may be used subject to the approval of the vet-
erinarian and bacteriologist.

Milk to be discarded. If the milk appears bloody, stringy, or other-
wise unnatural, or if dirt gets into it, it shall be discarded and the pail
washed and sterilized before it is again used.

Mil kino coics excluded from herd. Cows separated from the herd
shall be milked after the herd is milked or by other milkers than those
employed with the herd.

Cooling. Immediately after each cow is milked, the milk shall be
taken to the milk room for cooling and bottling.

CONDITION OF THE STABLE IN WHICH THE MILK is DRAWN.

The stable shall be kept scrupulously clean. Interior walls shall In-
light in color. If whitewash is used, a fresh coat shall be applied at least
three times a year, and oftener if necessary, to keep the walls clean and
white. Mold spots shall not be permitted.

Tools, when not in use, shall not be exposed in the stable.

The stable shall be thoroughly cleaned at least once daily. Neither
this nor other work which would stir up dust or odors shall be done
within thirty minutes before milking time.

While cows are being cleaned, the stable shall be thoroughly ventilated,
and the floor may be sprinkled to reduce the dust.

At least once every two months, the mangers shall be scrubbed with a
brush and soap, lye, or washing powder.

162 CERTIFIED MILK.

Calves, dry cows, horses, or other animals, or chickens, shall not be
allowed in the stable with milking" cows, nor in anv adjoining apartment.

No dust}- or moldy hay or straw, bedding from horse stalls, or other
unclean material shall be used for bedding cows.

PREPARATION OF THE MILKERS; THEIR CLEANING; THEIR DRESS.

A special room, conveniently located, shall be provided for the milkers
to wash in before and during milking.

Employees shall be clean in habits and appearance.

Contagious diseases. No person having an inflamed throat, or other-
wise out of health, shall be admitted to stable or dairy room.

The existence of smallpox, typhoid fever, diphtheria, scarlet fever,
measles, or other contagious disease on or in the vicinity of the dairy
shall be immediately reported to the Commission by telephone or tele-
graph, and the sale of milk shall be subject to the direction of the med-
ical inspector.

No person connected with the dairy shall enter a house where there is,
or has been, a contagious disease, until same has been disinfected, and
no person having entered such a house shall enter upon the dairy
premises.

While . engaged about the dairy or in handling the milk, employees
shall not use tobacco or intoxicating liquors.

Hands of Milkers. — Washing'. Before milking, the milker's hands
shall be thoroughly cleaned by the use of soap and a brush, and then
rinsed in clean water. He shall be careful not to touch anything but
the clean top of a milking stool, the milking pail, and the cow's teats.
The hands shall be kept dry when milking.

Milkers shall wear outer garments which are washed at least twice each
week, and, when not in use, kept, not in a dwelling, but in a clean,
ventilated place where dust does not have access and provided especially
for this purpose.

vSHAPE, PREPARATION, AND CONDITION OK VESSELS KOR RECEIVING

THE MILK.

The milk shall come in contact with no vessel or apparatus which is
not clean and practically sterile.

The opening of the milking pail shall not be larger than a circle seven
inches in diameter. A visor or hood to further reduce the opening is
recommended.

THE STRAINING, COOLING. AND BOTTLING OF THE MILK.

Promptly after milk is drawn, it shall be strained through a fine wire
gauze and a layer of absorbent cotton, protected on each side by a piece
of cheese cloth, or an equally good strainer.

AC.KKKMKXT WITH DAIRYMEN. 163

It shall be cooled at once to 50' I', or lower, and maintained below
50° F. until delivery. No ice shall be put into the milk.

The milk shall be bottled promptly, and may be bottled before cool-
ing, providing this system assures cooling within fifteen minutes from
the cow.

Milk shall be stored only in the milk room.

Water used for cooling or storage purposes shall be kept fresh and
free from odor.

No preservative or other substance shall be added to the milk for any
purpose, and no part of the milk shall be removed ; but the addition or
subtraction of cream may be practiced when specially permitted by the
Commission for the purpose of producing milk of guaranteed standard,
provided this does not conflict with milk laws and ordinances.

LOCATION AND CONDITION OF COOUNG AND BOTTLING ROOM.

The bottling room shall be within easy access of the stable, but so
placed that it cannot easily be reached by dust or odors from the stable
or yard or other source.

It shall be used for no other purpose than to provide a place for hand-
ling the milk, storing clean milk utensils, and holding fresh milk pre-
vious to its removal from the dairy.

This room shall be entered only by persons having business therein,
and wearing clean outer garments.

It shall be kept scrupulously clean.

Utensils shall be promptly removed after use and cleaned in another
room.

The milk room shall be well lighted and screened, and drained through
well-trapped pipes.

PACKAGES FOR THE TRANSFER OF MILK.

A flint glass bottle free from permanently attached parts shall be used
for the delivery of milk.

CLEANSING OF MILK CONTAINERS.

All milk containers and utensils shall be thoroughly cleaned by, hot
water and salsoda or other equally pure agent, rinsed until the cleaning
water is thoroughly removed, then exposed to live steam or boiling water
at least twenty minutes, then held until used where dust and other con-
taminating material will not have access.

SEALS.

Milk bottles shall be sealed as soon as possible after filling, and they
shall not be opened before delivery. A satisfactory seal consists of
melted paraffine carefully poured over the cap and impressed with date.

In addition to the stopper which confines the milk, the lip of the bottle
shall be protected by tin foil caps or heavy parchment paper circles.

164 CERTIFIKI) MILK.

HO\A* ARK THK CAPS FOR MlI.K BOTTIJiS MARKED?

Caps to close milk bottles shall be marked to sho\v the claimed quality
of the milk (or cream). On the caps or elsewhere, but accompanying
each package, there shall be stated the name of producer, name of dealer
(if different), name of Commission, guarantee of Commission, and expir-
ing date of same.

i
TRA XSPORTATION .

At no time between the cooling of the milk and its delivery shall its
temperature be allowed to exceed 50° F.

Bxcept when the outdoor temperature is below freezing, ice shall be
placed in the bottle cases.

Milk shall reach the consumer within thirty hours after production.

Experts employed by milk commissions. In the work of dairy
inspection and examination of the product, it is usual to employ
four experts, a veterinarian, a bacteriologist, a chemist and
a medical examiner. The compensation for their services,
always paid by the dairyman, is collected in various ways.
Some commissions sell bottle caps or other distinguishing
devices at a price that covers the whole expense of examination,
about five dollars per thousand. Others have a graduated fee
roughly proportional to the output of the dairy. In other
cases the dairyman pays a specific fee for each examination.
Very frequently public laboratories are able to make chemical
or bacteriological examinations gratis or for nominal fees.

Veterinary inspection. The duty of the veterinarian is to de-
termine the general health of the animals, to observe the sanitary
conditions and to scrutinize the technic of milk handling. In
general, his duty is to determine if the conditions of the agree-
ment of the dairyman with the commission are being observed.
His criticisms and suggestions must maintain that degree of
alertness on the part of the foreman of milkers and other
employees that shall minimize the possibility of contamination
of the milk.

The control of bovine tuberculosis is a task that demands
the utmost vigilance. Without care in regard to this disease,
the pretensions of a certified dairy are fraudulent. When
not rigorously dealt with, it constitutes the greatest menace to
the financial success of a certified dairv. Tuberculin tests

EXPERTS EMPLOYED BY MIUC COMMISSIONS. 165

a year apart, with careless supervision of additions to the herd,
are useless in a herd that was badly infected at the beginning,
for tuberculosis will keep pace- with lax efforts directed against
it. It is not sufficient to test merely the cows that happen to
be in milk at the time of the test. Every dry cow should be
included. In an infected herd, a test once in six months is
regarded as necessary, followed each time by thorough disin-
fection of the stable. The control of tuberculosis cannot be
accomplished by one test carried out in a perfunctory manner,
but the struggle must extend over years.

Additions to the herd must be tested with tuberculin, but
there is always danger that an animal, though not reacting,
may introduce the disease. On this account it is far better to
subject each animal added to the herd to a three months' quar-
antine with a tuberculin test at the beginning and end of this
period. During the period the milk may be used.

The details concerning the tuberculin test and management
of the disease are given in Chap. IV.

Bacteriological examinations. The numerical determination
of the bacteria in milk is made every week and constitutes a use-
ful check upon the methods employed in producing and hand-
ling the milk. A low count indicates that cleanliness has been
observed in the care of the utensils and in milking, and that
the product has been properly refrigerated. The bacterial
count is made of the milk when about the age that it ordinarily
is when it reaches the consumer. Care should be taken that
the sample be kept properly refrigerated until the examination
is made. The samples should be taken from the dairyman
unexpectedly as regards time and place. Thus it would be
impossible for him to submit extra good samples with fraud-
ulent intent. The numerical determination of the bacteria in
milk is a good safeguard against the fraudulent sale of ordi-
nary dirty milk under the guise of certified milk. There is a
very wide difference in the results that are obtained by exam-
ining the samples of these two classes of milk and thus fraud
may be detected.

The grade of milk designated "certified" should never
contain more than 10,000 bacteria percc. If there is a second

166 CERTIFIED MILK.

grade known as " Inspected " milk, it should not contain more
than 100,000 bacteria per cc. in summer and 60,000 bacteria
per cc. in winter. It is unfortunate and confusing' to have
milk commissions recognize two grades of milk. The technic
of the bacteriological examination of the milk is described in
Chap. VIII.

Reporting on samples and keeping records of results is facili-
tated by the use of a 3 by 5-inch card printed for the reception
of data as follows :

REPORT OF NUMERICAL DETERMINATION OF BACTERIA IN MILK.

Dairy. Reported

Collected at Date Hour...

Milk drawn at (A. \i.) (P.M.). Plated at. (A. M. ) ( p. M.)

Max. possible age hrs. Temperature when plated C.

Colonies per cc. Condition of package..

Chemical examinations . Chemical examinations are generally
made monthly. A committee of the American Association of
Medical Milk Commissions has made a report on chemical
standards, which is very briefly abstracted here (3). Milk rated
at 4% fat should range from 3.5% to 4. 5%, and 5% milk from
4.5% to 5.5%. The Babcock test is recommended, but in case
of condemnation for low fat control by the ether-extraction
method is desirable.

Protein estimations are not recommended as a routine.

It is suggested, that regular tests be made for formaldehyde
with the sulphuric acid-ferric chloride test, and if the test is
positive, that the specimen be distilled and the distillate tested.
Borax and boric acid may be looked for by the turmeric test.
Tests for salicylic acid, benzoic acid and benzoates may be
made four times a year at unexpected intervals.

It is recommended that tests for heated milk be regularly
carried out as a check against the use of undesirable high pas-
teurization temperatures, which alone can be detected by test.

Acidity tests of certified milk are of little importance. Like-
wise, a specific gravity standard need not be set for certified

TIIK CKKTIKIKI) MILK PACKAGE. 167

milk. Routine tests for specific gravity should he carried out
as a check against gross adulterations.

Medical inspection. The health of employees and of their
families offers an important field for the exercise of precau-
tionary measures. In some cases, a weekly postal card report
concerning health conditions is required of the dairy super-
intendent. The use of diphtheria swab examinations to
detect carriers of diphtheria infection about a dairy has not
been adopted, but might well be seriously considered. The
possibility that ' ' carriers ' ' of both typhoid fever and diphtheria
bacilli may work about a dairy without recognition by an ordi-
nary examination is a troublesome feature.

The certified milk package. The fundamental idea in the
delivery of certified milk is to have the milk bottles sealed at
the dairy and marked with a device indicating the approval of
the commission. The Brooklyn commission sells the dairy-
men bottle caps bearing a certification label, and illegitimate
use of them may be prevented by taking care that the consump-
tion of caps does not exceed the output of the certified herd.
After the caps are affixed in the bottles, a layer of paraffin is
placed over the cap and before it cools an impression is made
with a rubber stamp, marking the date upon which the milk
is to be sold and used. The stamps are the property of the
commission, and contain certain private marks by which the
experts of the commission may recognize the impression. The
stamps are assigned to different dairymen from time to time.
Other commissions issue slips bearing a statement concerning
certification, which are issued to the dairymen and placed over
the paper cap. Such a slip bears information as follows : ,

ST. LOUIS PURE MILK COMMISSION.
MILK COMMISSION CERTIFICATE.

Date ....

Milk or cream from the dairy of .and the

dairy itself have been recently examined by the experts of the Commis-
sion and found to be up to the required standards of excellence. Another
examination will be made within a month, and, if satisfactory, new labels
for the bottles will be issued dated (Notice the date.)

168 CERTIFIED MILK.

The top and lip of the bottle are protected by an additional
cap extending down over the neck. This may be of tinfoil with
ornamental lettering. Another device consists of a 6-inch
circle or square of parchment paper crumpled around the neck
and held in place by a rubber band. The paper may bear a
printed label.

Certified milk may be delivered in bulk to institutions in
cans the covers of which are fastened with a lead seal distinc-
tive of the certification of the commission.

Amount of certified milk produced. Certified milk at present
constitutes a very small percentage of the general milk supply.
Dr. Coit, in his presidential address before the American Asso-
ciation of Medical Milk Commissions, held in Chicago, in 1908,
made the following comment :

1 ' In New York City, the 10,000 quarts of certified milk is only one-half
of \% of the 1,800,000 quarts consumed daily, and if every quart of cer-
tified milk went to a baby, which it does not, it would be less than 5 ft
of all the babies in New York City, which is 205,000."

Certified milk has been before the public in New York since
1896, twelve years. The small amount consumed repre-
sents the small proportion of people in the country now who
realize the necessity for good milk and are able to pay for it.
The figures offer subject for thought in connection with the
problem of educating the public in the matter of paying twelve
to twenty cents a quart for good milk.

Certified milk is producing a good effect in the various com-
munities where it is known, out of 'all proportion to the amount
of such milk produced. It has been a potent factor in arous-
ing the present wave of interest in clean milk which is sweep-
ing over the country but is not a response to the demand for
pure milk for the masses.

Fraudulent certified milk. There was an instance in Louis-
ville, Ky., in \vhich a dealer employed two physicians and a
veterinarian on salaries and sold milk under their ' ' certifi-
cation." In another case, milk was sold as " certified milk "
on the basis of a falsified tuberculin test by two disreputable
veterinarians. The difficulty has been met in New York State
by legislative action as follows :

MAINTENANCE OF STANDARD. 169

' ' No person shall sell, exchange or offer or expose for sale, or exchange
as and for ' certified ' milk, any milk which does not conform to the regu-
lations prescribed by, and bear the certification of, a Milk Commission
appointed by a County Medical Society organized under and chartered by
the Medical Society of the State of New York and which has not been
pronounced by such authority to be free from antiseptics, added preser-
vatives, and pathogenic bacteria or bacteria in excessive numbers. All
milk sold as ' certified ' milk shall be conspicuously marked with the name
of the Commission certifying it."

In Kentucky a conviction has been obtained in the Circuit
Court, under the state pure food law, on the ground that the
fraudulent certified milk had been so advertised as to deceive
and defraud the public. It was established that the term ' ' cer-
tified milk " had come to have a distinctive meaning. -In Cal-
ifornia, the institution of similar proceedings under the pure
food and drugs act of that state induced a dairyman to stop
the illegitimate use of the phrase. Tuley (13) has discussed
this problem thoroughly.

Infringement in the matter of the use of .the term *•' certified
milk" cannot do very much harm, for it is a simple matter
for a medical milk commission to notify the profession and
the public of the fraudulent nature of the claims.

Maintenance of standard. That the milk produced in a
number of certified dairies is really what it is claimed to be by
the milk commissions controlling those dairies has been shown
in an investigation conducted by the Dairy Division of the
U. S. Department of Agriculture.

Sixteen dairies were visited and scored by a representative
of the department. The average score was 93.4 on a scale of
100 (perfection). The average score of several details was as
follows : Cows, 99.5 ; stable, 87.2 ; milk house, 94.5 ; milking,
94.0; handling of milk, 93.0. It should be noted that the
high score of the cows was based largely upon credit given for
the tuberculin test required by all commissions, but which was
not made by the Department of Agriculture.

Twelve samples of certified milk (four days old) were scored,
with an average of 86.0. The bacterial count varied from 280
to 19,000 per cc. (8).

170 CERTIFIED MILK.

Milk dispensaries. In France, the decreasing birth rate first
stimulated an interest in agencies for decreasing the death rate
of infants. One form of institution called "consultation dc
nourrisons " is attached to maternity hospitals. Children born
in the hospital are kept under medical supervision for two years.
They are brought to the hospital once a week, weighed, and
medical advice is given the mother. A slightly different sort
of institution, goittte de /ait (milk dispensary), furnishes milk
to the poor in general.

In the work of milk dispensaries the aim is to decrease infant
mortality among the poor by remedying methods of care and
feeding. Breast feeding is urged, but when this is impossible,
a pure supply of milk is provided. When the circumstances
demand, the milk is modified to meet the requirements of the
individual infant. Instruction in the proper hygienic care of
infants is recognized as quite as important as pure food. This
is accomplished most effectively by oral instruction, supple-
mented by educational pamphlets.

Milk dispensaries are maintained in about twenty cities in
the United States. In ten of these, the milk is pasteurized at
various temperatures. In six cases certified milk is used and
in the others milk from good sources. In general the milk
dispensaries are maintained during the summer only, but in
some cases they are open during the whole year. Milk dis-
pensaries are maintained as charities. Nathan Straus of New
York is particularly active in this form of philanthrophy. Out
of the twenty cities in which there are milk depots, only four
of them are maintained at the expense and under the super-
vision of the health department.

There are so many factors involved that it is impossible to
place a valuation upon the influence of the clean milk alone,
even though the work of milk dispensaries is an important
factor in reducing infant mortality (9, 10).

Rochester, A\ }\ , ;;////• dispensaries. Dr. Goler, the Health
Officer of Rochester, N. Y., has established milk depots under
the control of the health department. A contract is made for
the product of a dairy during two months in the summer.
A temporary laboratory is established at the farm and em-

^Vf

^- — ,f- JI.».«T,

MILK DISPENSARIES.

171

<j7 c™j su?

di ii U

Jan

feb

mar

Opr

may

Jun I July

Pug

Ckl

Dec

Soo

\

\

\

/'/{,'. 77. C/icii'f Showing relation of municipal milk stations to infant

mortality (6).

172 t CERTIFIED MILK.

ployees of the department supervise the production of the milk,
and take charge of it immediately after drawing. The various
modifications are made, and the product is shipped in the
nursing bottles to the various city dispensing stations. There
are four of these stations, each in charge of a trained nurse.
The instruction in the care of infants is facilitated by pamph-
lets printed in English, German, Italian and Yiddish.

Fig. 17 by Goler (6) shows the beneficial effects resulting
from the establishment of milk stations. The work is accom-
plished for a season of two months at an expense of about one
thousand dollars a year. The system of control of the pro-
duction of the milk makes it possible to use raw milk (5, 6).

The practicability of municipal control of milk .stations has
been demonstrated, and there is every reason for the adoption
of this line of work by other municipalities.

REFERENCES.

1. AMERICAN ASSOCIATION OF MEDICAL MILK COMMISSIONS. Pro-
ceedings of the first annual session. Published by the Secretary, Dr.
Otto P. Geier, 124 Garfield Place, Cincinnati, Ohio, 1907.

2. CoiT. A brief history of the development of the pure milk move-
ment in the United States. Paper read at the Congres Internationale
des Gouttes de Lait, Brussels, 1907.

2 a. CoiT. Clean milk in its economic and medical relations with
special reference to certified milk. Kentucky State Medical JouruaL
May, 1908.

3. EBSALL, VAN SLYKE and CHAPMAN. Report of the committee on
chemical standards. Pediatrics, Vol. XX, 1908, No. 7, p, 455.

4. GiER. Our experience with certified milk in Cincinnati. Kentucky
Med. Jour., Vol. VI, 1908, p. 276.

5. GOLER. But a thousand a year. Charities, August 5, 1905.

6. GoLER. Scheme for the sanitary control of the municipal milk
supply. Paper read at the Congres Internal ionale des (.>outtes de Lait ,
Paris, 1905.

7. KERR. Certified milk and infants' milk depots. Bui. Xo. 41,
Hyg. Lab., U. S. Pub. Health and Mar. Hasp. Sen'., Washington, D. C.,
1908, p. 565.

RKPKRKXCKS. 173

8. lyANK. Medical milk commissions and the production of certified
milk in the United States. Jiiil. \o. 10f, I>itr. Auini. hid., f '. .V. /)r/>/.
Agr., Washington, D. C., 1908.

9. McCi^KARV. Infant mortality and infants' milk depots. London:
P. S. King & vSon, 1905.

10. McCivKARY. The infants' milk depot. Its 'history and function.
Jour. //K<f-> Vol. IV, 1904, p. 329.

11. PKARSON, LKONARD. Report of the committee on the inspection
of herds and farms used for the production of certified milk. Pediatrics,
Vol. XX, 1908, No. 8, p. 500.

12. PKARSON, R. A. Market milk: A plan for its improvement.
Seventeenth Ann. Rept. Bur. Anim. Ind., f T. S. Dept. Agr., Washing-
ton, D. C., 1900, p. 158.

13. TuivEY. legislation as a factor in the production of clean milk.
Pediatrics, Vol. XX, 1908, No. 8, p. 487.

14. WARD. Milk production under hygienic conditions. Occidental
Medical Journal, Vol. XVI, 1902, p. 178.

CHAPTER X.

THE ANALYSIS OF MILK.

Introduction. In addition to the data obtained from the
sanitary inspection of dairies, the health officer should be in a
position to inform himself as to the composition of the milk as
sold. It is with a view to supplying" such necessary aid that
these two chapters are here presented. It is not intended to
offer full and complete details for the analysis of milk but rather
to give some simple and at the same time accurate and reliable
tests for ascertaining not only the fat content but also whether
or not a milk has been in any way sophisticated. For further
details the reader is directed to the standard works mentioned
at the end of the chapter.

Composition of milk. Normal cow's milk contains water
and the four nutrients, protein, fat, carbohydrate and ash or
mineral matter.

Protein. Casein is the chief proteid of milk, constituting
fully 80% of the total amount, the next in importance being
albumen present to the amount of 15f/r . The remaining 5'/r
consists of different nitrogenous compounds, as lactoglobulin,
galactin, fibrin, etc.

The protein content of normal herd milk does not vary
greatly, but that of individual cows has been known to range
from 2.07% to 6.69'/< .

Fat. This is the most variable ingredient of milk. It does
not occur in solution but is found suspended in the form of
minute globules. These vary in size not only with the milk of
the different breeds but also with the same breed or individual
during the period of lactation. It is a well known fact that
the Channel Island breeds, Jerseys and Guernseys, yield milk
showing the highest fat content and the Holstein-Friesian
cattle as a rule produce milk of a low fat content.

COMPOSITION OF MILK.

175

The fat percentage of milk not only varies with the differ-
ent breeds but also in different portions of the same milking,
as shown in the following table from Aikman (l).

TABLE vii.

VARIATION OF SOLIDS IN DIFFERENT PORTIONS OF ONE MILKING.

PORTION.

FIRST.

SlCCOND.

THIRD.

FOURTH.

FIFTH.

SIXTH.

Per cent.

Percent.

Per cent.

Per cent.

Per cent.

Per cent.

Total solids

10.47

10.75

10.85

11.23

11.63

12.67

Fat

1.70

1.76

2.10

2.54

3.14

4.08

Solids not fat

8.77

8.99

8.75

8.69

8.49

8.59

It must be borne in mind that in mixed herds the product
varies in fat percentage to a considerable degree. Some bot-
tles or even cans will be unnecessarily rich in fats at the
expense of others which will run below standard. This cir-
cumstance may result in the condemnation of the milk, due
entirely to careless manipulation, when the average of the herd
may be entirely satisfactory. The whole output of a herd at
one milking is not mixed in one receptacle and then trans-
ferred to cans or bottles. The usual practice is to take the
milk of a few7 cows at a time for bottling. Even under these
circumstances there is danger that the fat will rise in the vat
under the cooler unless the milk is bottled immediately after
cooling. Too much emphasis cannot be placed upon this
important point in the handling of any milk and especially
with reference to the product of certified dairies. This milk;
so frequently modified for infant feeding, should be of uniform
composition.

The difficulties encountered are best obviated by alternating
in the stable, or in the order of milking, the cows known to
yield milk of high fat content with those known to give poor
milk. In the case of the Channel Island breeds and the
Holstein-Friesians this is a simple matter. In the case of
scrub cows this recognition may not be so easy -and depend-
ence must be placed upon the results of the examination of the
milk of these cows for fat by the Babcock test.

176

THE ANALYSIS OF MILK.

Carbohydrates. Milk sugar, the carbohydrate of milk, con-
stitutes between 4.5% and 5% of the milk.

Mineral matter. The ash, as stated by Leach (2), does not
represent the true mineral content of milk, since in the process
of incineration some of the constituents are altered. For
instance, citric acid occurring hi small quantities in normal
milk will appear in the ash as carbonic acid in combination.
Several other illustrations could be given.

The ash, in all probability, is the least variable of any of the
ingredients of milk and for that reason is often made the basis
of calculating the composition of an original milk from the
analytical results of the examination of a condensed milk.

Solids of milk. The protein, fat, sugar and ash comprise
what are designated as milk solids. The sugar, protein and
mineral matter constitute the solids not fat. These latter, with
the water, are known as the milk serum.

The average composition of milk, its derivatives and colos-
trum, are shown in the following table.

TABLE VIII.
COMPOSITION OF MILK, ETC.

CONSTITUENTS

WATER.

FAT.

SUGAR.

PROTEIN.

ASH.

AUTHORITY.

Per cent.

Per cent.

Per cent.

Per cent.

Per cent.

Milk

87.3

3.6

4.6

3.8

.7

Babcock.

Skim-milk..

90.3

.1

5.2

3.6

.8

Van vSlvke.

Buttermilk ..

91.0

.5

4.8

3.0

.7

Atwater.

Cream

68.8

22.7

4.2

3.8

.5

Ko'nig.

Colostrum ....

74.5

3.6

2.7

17.6

1.6

Konig.

Effect of feeding on the composition of milk. The idea is
prevalent among dairymen throughout the country that the
quality of the milk may be improved by modification of the
feeding of the cows. The problem has been investigated many
times by eminent authorities. Conclusions have been reached
as follows :

1 . If a cow is being properly fed, that is, receiving a balanced
ration suitable for her individual needs, the quality of the milk

SAMPLING MILK. 177

is not appreciably affected by an increase of any of the ingred-
ients of the ration.

2. Under such circumstances fat cannot be fed into milk.

Sampling' milk. The first consideration in the examination
of milk is the sampling. It is of the utmost importance that
a representative sample be taken and too much emphasis can-
not be placed on this point. Great care is called for in samp-
ling milk because, as previously stated, the fat of milk is not
in solution, but held in suspension, and forms an emulsion
with the milk serum. The little globules of fat commence
to rise very soon after milk is allowed to stand and, to the
uninitiated, surprisingly fast. The writer has analyzed three
different samples of milk from the same herd showing respect-
ively 2.9%, 9.1% and 3.6% fat. The variations were due en-
tirely to improper sampling. The sample should be taken and
the examination conducted while the milk is fresh and in normal
condition. If the samples are to be transported to any distance
previous to being tested, care should be taken to see that the
bottles are completely filled. This will avoid the tendency to
churn which might cause the fat to collect in lumps and pre-
vent, at times, an accurate determination of the fat.

After a sample is properly taken it should be thoroughly
mixed before it is tested and the respective portions for the
different tests should be measured immediately after mixing.
If such a practice is not adopted, serious inaccuracies are liable
to occur, owing to the rapidity with which the fat globules will
rise toward the surface. By far the best way to mix a sample
is to pour it from one vessel to another, and the pouring should
be done on the side of the vessel and not in the center. If this
precaution is not taken an appreciable amount of air will be
incorporated in the milk, which will greatly interfere with the
accurate measuring of the milk for the Babccck test for fat.

There are on the market several different devices for sam-
pling market milk, such as the Scovell, McKay, and Equity
sampling tubes, etc. These with full directions for use may
be obtained from dairy supply houses.

Specific gravity. The specific gravity of a thoroughly mixed
sample may be most conveniently taken by means of the small

178

THE ANALYSIS OF MILK.

hydrometer with the thermometer attached. This is about
seven inches long and has a range of from 1.000 to 1.060.
There are several different forms of lactometers on the market
but they are not any better adapted for milk than is the hydrom-
eter to which reference has just been made. All readings
should be made whenever possible at 60° F. (15.6°C.). When-
ever this cannot be done correction must be made in accordance
with the table below, taken from Richmond (12).

TABLE IX.
FOR CORRECTING SPECIFIC GRAVITY TO 60°F.

J*

DEGREES OF SPECIFIC GRAVITY OBSERVED.

25

26

27

28

29

30

31 i 32

33

34

35

36

ft

Specific Gravity corrected to 60°F.

40

23.5

24.5

25.5

26.4

27.3

28.2

29.1

30.0

31.0

31.9

32.8

33.7

42

23.6

24.6

25.6

26.5

27.5

28.4

29.3

30.2

31.1

32.0

32.9

33.9

44

23.8

24.8

25.8

26.7

27.7

28.6

29.5

30.4

31.3

32.2

33.1

34.1

46

23.9

24.9

25.9

26.8

27.8

28.7

29.6

30.5

31.4

32.4

33.3

34.3

48

24.0

25.0

26.0.

26.9

27.9

28.8

29.7

30.6

31.6 32.6

33.5

34.5

50

24.1

25.1

26.1

27.0

28.0

29.0

29.9

30.9

31.8 32.8

33.7

34.7

52

24.3

25.2

26.2

27.2

28.1

29.1

30.1

31.1

32.0

33.0

33.9

34.9

54

24.5

25.4

26.4

27.4

28.4

29.3

30.3

31.3

32.3

33.3

34.2

35.1

56

24.6

25.6

26.7

27.6

28.6

29.6

30.5

31.51 32. 5

33.5

34.4

35.4

58

24.8

25.8

26.8

27.8

28.8

29.8

30.8

31.7

32.7

33.7

34.7

35.7

60

25.0

26.0

27.0

28.0

29.0

30.0

31.0

32.0

33.0

34.0

35.0

36.0

62

25.2

26.2

27.3

28.3

29.3

30.3

31.3

32.3

33.3

34.3

35.3

64

25.4

26.5

27.5

28.5

29.5

30.5

31.5

32.6

33.6

34.6

35.6

66

25.6

26.7

27.7

28.7

29.8

30.8

31.8

32.9

33.9

34.9

35.9

68

25.9

27.0

28.0

29.0

30.1

31.1

32.1

33.2

34.2

35.2

36.2

70

26.1

27.2

28.2

29.2

30.3

31.3

32.4

33.4

34.5

35.5

36.5

72

26.4

27.4

28.4

29.5

30.5

31.6

32.6

33.7

34.7

35.8

74

26.6

27.7

28.7

29.7

30.8

31.9

32.9

34.0

35,0

36.1

76

26.9

27.9

28.9

29.9

31.0

32.2

33.3

34.4

35.4

36.5

78

27.2

28.2

29.2

30.3

31.4

32.5

33.6

34.7

35.8

36.9

80

27.4

28.4

29.5

30.6

31.7

32.8

33.9

35.0

36.0

The specific gravity of milk from normal, healthy cows will
vary from 1.029 to 1.035 at 60° F (15.6° C). The average for
normal milk as determined by the writer from a large number
of samples agrees well with the figures obtained elsewhere,
namely 1.032. Too much stress cannot be placed on the spe-
cific gravity determination, because it is a simple matter to add

DETERMINATION OF FAT IN MILK AND CREAM. 179

water to milk and then some easily soluble material to bring
the gravity back to the normal. Nevertheless, the determin-
ation of the gravity is of great assistance to the health officer
and physician.

The use of the determination of the specific gravity in the
detection of added water is discussed in Chap. XI.

Determination of fat in milk and cream, Fat being the most
variable ingredient of milk, it is only logical that all commer-
cial transactions relative to milk should be based upon the fat
content. It was this that gave the incentive to a number of
agricultural chemists twenty years ago, upon the establish-
ment of the agricultural experiment stations, to devise a simple,
rapid and accurate method for the determination of fat, which
could be intelligently used by those who either had no training
in chemistry or could not obtain access to a chemical laboratory.
The method now in common use is the one given free to the
public in 1890 by Dr. S. M. Babcock of the Wisconsin Agri-
cultural Experiment Station. The details of this adrnirable
test are hardly called for here ; for such, and other valuable
and useful data, the reader is referred to that excellent little
work, "Testing Milk and Its Products," by Farrington and
Woll (5). Also, to " Modern Methods of Testing Milk and
Milk Products," by Van Slyke (14).

It may be said, however, in supplementing the directions
usually given for this test that the addition of 2 cc. of an 80%
solution of glycerin, as recommended by Holm (7), to the milk
in the test bottle just previous to adding the acid will insure
a clearer line of demarcation than is ordinarily obtained be-
tween the fat and water in the graduated neck of the bottle;

Another modification which has proved useful in the testing
of cream by the Babcock method is that obtained by Kckles
and Wayman of the Dairy Department of the University of
Missouri. It consists in dropping a small quantity of amyl
alcohol colored with fuchsin or any red dye on top of the col-
umn of butter fat before it is read. Since it is lighter than the
fat, it floats on the surface. This removes the meniscus from
the surface of the fat to the top of the amyl alcohol, and leaves
a perfectly straight line across the top of the fat column. Thus

180 THE ANALYSIS OF MILK.

the reading" of the fat is made more accurately than when an
attempt is made to read either to the bottom or center of the
meniscus.

It is best to read the fat column immediately after the addi-
tion of the alcohol, because, if the latter is allowed to remain
in the fat column for several hours, it mixes with the fat to a
certain extent and the reading cannot then be taken accurately ;
but this does not occur short of two hours. This modification
has proven of great assistance in the manipulation of the Bab-
cock test for the determination of fat in cream and gives results
which compare very favorably with the gravimetric method and
the ordinary way of reading the fat column in the Babcock
bottle. Webster (15) has made a very exhaustive study of
the testing of fat in cream by the Babcock test.

In the hands of a competent operator, the Babcock test gives
as reliable and accurate results as those obtained by the com-
plicated ether extraction method.

Interpretation of specific gravity and fat. It is almost impos-
sible to lay down any hard and fast rules concerning the inter-
pretation to be placed upon the specific gravity and fat content.
It may be said in general with reference to milk from herds in
normal condition that :

1. High gravity with high fat content indicates a rich milk.

2. High gravity with low fat content indicates either a
poor milk or that the milk has been skimmed.

3. Low gravity with high fat content indicates ' ' top milk, ' '
that is, the sample has been taken from a quantity of milk
which has been allowed to stand some time previous to sam-
pling.

4. Low gravity, in connection with low fat content, indi-
cates a watered milk.

Solids not fat. While it is true in many instances that the
fat per cent, and specific gravity are sufficient to enable the
inspector to judge of the quality of milk, at the same time it
is a simple matter to obtain the solids not fat by calculation.
Formulas for such calculation have been worked out by Bab-
cock, Fleischmann, Richmond and others. The one in general
use in this country is Babcock 's formula.

TABLE X.
PER CENT. OF SOLIDS NOT FAT, CORRESPONDING TO 0 TO 6

PER CENT. OF FAT, AND SPINDLE READINGS OF 26 TO 36.
SPINDLE READINGS AT 60° F. Z^ZZHZZ^Z!

26 27 28 29 30 31 32 33 34 35 36

0.0

6.50

6.75

7.00

7.25

7.50

7-75

8.00

8.25

850

8.75

9-00

0.0

0.1

6.52

6.77

7.02

7.27

7-52

7-77

8.02

827

852

8-77

9-02

0.1

0.2

6.54

6.79

•7.04

7.29

7.54

7-79

8.04

8.29

8.54

•879

9-04

0.2

0.3

6.56

6.81

7.06

7.31

7.56

781

8.06

831

8.56

881

9-06

0.3

0.4

6.58

6.83

7.08

7.33

7.58

783

8.08

8.33

858

8.83

9-08

0.4

0.5

6.60

6.85

7.10

7.35

7.60

785

810

8.35

860

8.85

9-10

0.5

0.6

6.62

6.87

7.12

7.37

7.62

787

8.12

8.37

862

8.87

9.12

0.6

(.7

6.64

6.89

7.14

7-39

7.64

7-89

8.14

839

864

8.89

914

0.7

O.S

6.66

6.91

7.16

7-41

7.66

7-91

8.16

8.41

8.66

8.91

916

0.8

0.9

6.68

6.93

7. IS

7.43

7-68

7-93

818

843

868

8-93

918

0.9

.0

6.70

6.95

7.20

7-45

7-70

795

8.20

8.45

8.70

895

9-20

1.0

.1

6.72

6.97

7.22

7-47

7-72

797

8.22

8.47

872

8-97

9.22

1.1

.2

6.74

6.99

7.24

7.49

7-74

7-99

824

849

874

8.99

9.24

1.2

.3

6.76

7.01

7.26

7.51

7-76

801

8.26

851

8.76

901

9.26

1.3

.4

6.78

7.03

7.28

7.53

7-78

803

828

853

878

9-03

928

1.4

.5

6.80

7.05

7.30

7.55

7.80

805

830

8.55

880

905

9-30

1.5

.6

6.82

7.07

7.32

•7.57

7.82

807

832

8.57

882

9-07

9 S2

1.6

.7

6.84

7.09

7.34

7.59

7.84

8.09

834

859

884

9-09

9,34

1.7

.8

6.86

7.11

7.36

7.61

7.86

8J1

8.36

8.61

886

911

937

1.8

.9

6.88

7.13

7.38

7.63

7.88

8.13

838

863

888

9.13

939

1.9

2.0

6.90

7.15

7.40

7-65

7.90

815

8.40

866

891

9.16

9-41

2.0

2.1

6.92

7.17

7.42

7.67

7.92

817

842

868

893

918

943

2.1

2.2

6.94

7.19

7.44

7-69

7-94

8.19

8.44

8.70

895

9-20

945

2.2

2.3

6.96

7.21

7.46

7-71

7-96

821

846

8.72

897

922

9 47

2.3

2.4

6.98

7.23

7.48

7-73

7-98

823

8.48

8.74

899

9,24

949

2.4

2.5

7.00

7.25

7.50

7-75

8.00

8.25

850

876

901

9.26

951

2.5

2.6

7.02

7.27

7.52

7-77

8.02

827

852

878

903

9 28

953

2.6

2.7

7.04

7.29

7.54

7-79

8.C4

8.29

854

880

905

930

955

2.7

2.8

7.06

7.31

7.56

7.81

8.06

831

8.57

882

907

932

9-57

2.8

2.9

7. OS

7.33

7.58

7.83

8.08

833

858

8.84

909

934

9-59

2.9

3.0

7.10

7.35

7.60

7.85

8.10

8.36

8.6l

8.86

9 11

9 36

9-61

3.0

3.1

7.12

7.37

7.62

7.87

8.13

838

863

8.88

913

938

964

3.1

3.2

7.14

7.39

7.64

7.89

8.15

8.40

865

890

915

941

9.66

3.2

3.3

7.16

7.41

7.66

7-92

8.17

842

8.67

892

918

943

968

3.3

3.4

7.18

7.43

7.69

7.94

8.19

8.44

869

894

9-20

9-45

9-70

3.4

3.5

7.20

7.45

7.71

7-96

8.21

846

8*71

8.96

922

9-47

9.72

3.5

3.6

7.22

7.48

7-73

7-98

8.23

8.48

873

898

924

949

974

3.6

3.7

7.24

7.50

7.75

8.00

8.25

850

8:5

900

926

9-51

976

3.7

3.8

7.26

7.52

7-77

8.02

8.27

852

877

902

9-28

9-53

978

3.8

3.9

7.28

7.54

7-79

8.04

8.29

8.54

8.79

904

930

955

980

3.9

4.0

7.30

7.56

7-81

8.06

8.31

856

881

9.06

932

957

9-83

4.0

4.1

7.32

7.58

7.83

8.08

8.33

858

8.83

908

934

959

9-85

4.1

4.2

7.34

7.60

7.85

8.10

8.35

8.60

885

911

936

962

987

4.2

4.3

7.36

7.62

7-87

8.12

8.37

862

8.88

9.13

9-38

964

989

4-3

4.4

7.38

7.64

7.89

8.14

8.39

864

890

9.15

9.40

966

991

4.4

4.5

7.40

7.66

7.91

8.16

8.41

8.66

8.92

9.17

942

968

993

4.5

4.6

7.43

7.68

7.93

8.18

8.43

8.68

894

9.19

9-44

970

995

4.6

4.7

7.45

7.70

7.95

8.20

8.45

8.70

896

9.21

9.46

9.72

997

4.7

4.8

7.47

7.72

7.97

8.22

8.47

872

8.98

9.23

948

9-74

9-99

4-8

4.9

7.49

7.74

7.99

8.24

8.49

8.74

9-00

9.25

9-50

976

10.01

4-9

5.0

7.51

7.76

8.01

8.26

8.51

8.76

9-02

9.27

952

978

10.03

5.0

5.1

7.53

7.78

8.03

8.28

8.53

879

904

9.29

954

980

10.05

5.1

5.2

7.55

7.80

8.05

8.30

8.55

8.8l

906

9.31

9-56

9.82

10.07

5.2

5.3

7.57

7.82

8.07

8.32

8.57

8.83

908

9.33

958

984

10.09

5.3

5.4

7.59

'7.84

8.09

8.34

8.60

8.85

910

9.36

9-61 '

9.86

10.11

5.4

5.5

7.61

7.86

8.11

8.36

8.62

88?

912

9.38

963

9.88

10.13

5.5

5.6

7.63

7.88

8.13

8.39

8.64

8.89

9-15

9.40

965

990

10.15

5.6

5.7

7.65

7.90

8.15

8.41

8.66

8.91

9-17

9.42

967

992

10.17

5.7

5.8

7.67

7.92

8.17

8.43

8.68

8.94

9-19

9.44

969

994

10.19

5.8

5.9

7:69

7.94

8.20

8.45

8.70

8.96

921

9.46

971

996

10.22

5.9

6.0

7.71

7.96

8.22

8.47

8.72

8.98

9-23

9.48

973

9.98

10.24

6.0

182 THE ANALYSIS OF MILK.

Table X, page 181, based upon this formula and taken from
Farrington and Woll, shows the solids not fat and spindle
readings of 26 to 36. The spindle readings refer to the last
two figures of the specific gravity ; for instance, if the specific
gravity were 1.032, this would be represented in the table by
spindle reading 32.

It is thus seen that by adding the fat and solids not fat the
total solids of the milk are obtained. In nearly all cases the
difference between the actual determination of the solids not
fat and the figure obtained by calculation does not differ mater-
ially. The inspector consequently by merely determining the
fat and the gravity will be in a position to judge whether or
no milk under examination is or is not up to the required
standard for pure milk.

Preliminary tests of milk. It is often desirable to make pre-
liminary tests of milk with reference to its quality, for which
there are to be obtained several devices. These are well
described by Wing (6), who also gives a very interesting sum-
mary of the development of the tests for fat previous to the
invention of the BabcOck test.

Acidity of milk. This is a point which should receive more
attention from the health officer than it ordinarily does. Milk
fresh from the COWT will often show an amphoteric reaction
but soon afterwards it will show an acid reaction and this acid-
ity will vary greatly, depending entirely upon how the milk
has been handled. The Committee on Chemical Standards of
the American Association of Medical Milk Commissions rec-
ommended that the maximum acidity of milk allowed should
be 0.18 c/(. calculated as lactic acid. The writer considers this
to be a very generous standard.

The acidity of milk should be determined at times but not
as a routine procedure. This may very easily be done by the
use of the Farrington alkaline tablet test as fully described in
Farrington and Woll (6). The test is very simple and does
not require an expensive outlay for apparatus, but it must be
emphasized that only distilled water or a clean, non -alkaline
soft water should be used for dissolving the tablets.

FEDERAL STANDARDS. 183

A high acidity indicates bacterial changes, the result of some
combination of the factors of uncleanliness, poor refrigeration
and age.

Federal standards. In connection with the enforcement of
the pure food and drugs act, the following standards proclaimed
by the Secretary of Agriculture have been adopted (13).

MIIvK AND ITS PRODUCTS.

1. Milk is the fresh, clean, lacteal secretion obtained by the complete
milking of one or more healthy cows, properly fed and kept, excluding
that obtained within fifteen days before and ten days after calving, and
contains not less than eight and one-half (8.5) per cent of solids not fat,
and not less than three and one-quarter (3.25) per cent of milk fat.

2. Blended milk is milk modified in its composition so as to have a
definite and stated percentage of one or more of its constituents.

3. Skim milk is milk from which a part or all of the cream has been
removed and contains not less than nine and one-quarter (9.25) per cent
of milk solids.

4. Pasteurized milk is milk that has been heated below boiling but
sufficiently to kill most of the active organisms present and immediately
cooled to 50° Fahr. or lower.

5. Sterilized milk is milk that has been heated at the temperature of
boiling water or higher for a length of time sufficient to kill all organ-
isms present.

6. Condensed milk, evaporated milk, is milk from which a considera-
ble portion of water has been evaporated and contains not less than
twenty-eight (28) per cent of milk solids of which not less than twenty-
seven and five-tenths (27.5) per cent is milk fat.

7. Sweetened condensed milk is milk from which a considerable por-
tion of water has been evaporated and to which sugar (sucrose) has been
added, and contains not less than twenty-eight (28) per cent of milk sol-
ids, of which not less than twenty-seven and five-tenths (27.5) per cent
is milk fat.

8. Condensed skim milk is skim milk from which a considerable por-
tion of water has been evaporated.

9. Buttermilk is the product that remains when butter is removed
from milk or cream in the process of churning.

10. Goafs milk, ewe^s milk, et cetera, are the fresh, clean, lacteal
secretions,, free from colostrum, obtained by the complete milking of
healthy animals other than cows, properly fed and kept, and conform in
name to the species of animal from which they are obtained.

184 THE ANALYSIS OF MILK.

b. CREAM.

1. Cream is that portion of milk, rich in milk fat, which rises to the
surface of milk on standing, or is separated from it by centrifugal force,
is fresh and clean and contains not less than eighteen (18) per cent of
milk fat.

2. Evaporated cream, clotted cream, is cream from which a consider-
able portion of water has been evaporated.

State standards. In drafting local dairy ordinances it is
desirable to have the standards conform to the requirements of
the state law. In California, the courts have ruled that the
city ordinances can conflict with those of the state to the ex-
tent of raising the local standard above that adopted by the
state.

Collection of samples. One of the most important and
weighty considerations is the proper collection of milk samples.
This necessitates the employment of trained inspectors. It
would appear from the experience of the writer that this point
'is not ordinarily kept in mind when officers are appointed.
The inspector should either be a dairy-school graduate well
recommended or should receive the necessary training in the
laboratory with which he is to be associated.

Samples from milk cans, whether from store or wagon, should
be collected with care in the matter of mixing as pointed out
on page 177. An additional precaution regarding the use of
the sampling tube might not be out of place. The tube should
be thoroughly rinsed after each sample has been taken in order
to preclude the possibility of contaminating one sample with
traces of a preservative that might have been in the previous
one.

One of the most convenient receptacles for collecting milk is
a wide-mouthed eight-ounce bottle with a well-fitted cork.
Duplicate samples 'should be collected in order that the party
from whom the sample is taken may retain one for analysis if
he so desires. Dairy ordinances should require that this be
done.

In the case of bottled milk also it would appear to be desir-
able to collect duplicate samples. This may readily be done
by the inspector carrying in his outfit a clean quart bottle for

RKFKKKNCES. 185

mixing samples. He would thus be enabled to thoroughly
mix the contents of a sample of bottled milk in the presence
of the vender and to give half to the vender as a duplicate.
If this method is followed there can be no dispute as to the
authenticity of the samples collected.

It is highly essential that the inspector be provided with a
book- of numbered blank forms containing also small slips bear-
ing duplicate numbers. One of these slips should go on each
sample for purposes of identification. The blanks should call
for information covering the essential facts regarding the source
of the sample and should be in duplicate. The inspector
retains the original in his book and the duplicate goes with
the sample to the chemist.

All samples must be duly sealed in the presence of the vender.
This may be done by the use of gummed paper strips printed
with an appropriate legend and pasted over the cork. The
seal bears a printed number corresponding to that of the blank
form. Sealing wax impressed with a distinctive device may
also be used for the purpose of sealing the sample. In this
case the cork must be flush with the top of the neck of the
bottle, for the wax is smeared over both.

REFERENCES.

1. AIKMAN. Milk, its nature and composition. London: Adam and
Charles Black, 1899.

2. ALLEN. Commercial organic analysis. Vol. IV. Philadelphia :
P. Blakiston's Son & Co., 1898.

3. ATWATRR and BRYANT. Chemical composition of American food
materials. Bui. No. 28 (revised}, Office of E.rp. Sta., L\ S. Dept.
Agr., Washington, D. C., 1906.

4. BL.YTH. Foods, their composition and analysis. London: Ch.
Griffin & Co., Ltd., 1903.

'5. FARRINGTON and Wot,!,. Testing milk and its products. Madi-
son, Wis.: Mendota Book Co., 1908.

6. FARRINGTON. Variations in milk. /////. No. 24, I'uiv.of III.
Agr. Exp. Sta., Urbana, 111., 1893.

186 THE ANALYSIS OF MILK.

7. HOLM. A new method for preventing char in the Babcock centrif-
ugal determination of fat in milk and milk products. Atner. l^ood
Jonr., Vol. II. 1907, No. 7. p. 28.

8. KASTLE and ROBERTS. The chemistry of milk. J>nl. Xo. 41 ',
Hyg. Lab., ('. S. l^nb. Health and Mar. Hosp. Sen*., Washington. D. C.,
1908, p. 309.

9. LANCAYORTHY. Milk as food. Faniirrs' J'>nl. Xo. 7X, ( '. S. Dept.
Agr., Washington, D. C., 1904.

10. LEACH. Food inspection and analysis. New York : John Wiley
& Sons, 1906.

11. RICHMOND. Dairy chemistry. London: Ch. Griffin & Co., Ltd.

12. RICHMOND. The laboratory lx>ok of dairy analysis. London :
Ch. Griffin & Co., Ltd., 1899.

13. SECRETARY OF AGRICULTURE. Standards of purity for food pro-
ducts. Cir. No. 19, Office of the Secretary, U. S. Dept. A or., Wash-
ington, D. C., 1906.

14. VAN SivYKE. Modern methods of testing milk and milk pro-
ducts. New York: Orange Judd Co. , 1906.

15. WEBSTER. The fat testing of cream by the Babcock method.
Hill. Xo. 58, Bur. Anini. Ind., ('. S. Dept. Agr., Washington, D. C..
1902.

16. WILEY (EDITOR). Official and provisional methods of analysis,
Association of Official Agricultural Chemists. />'///. Xo. 1<>7 (revised),
r>nr. of Cheui., ( '. S. Dept. Agr., Washington, D. C., 1908.

17. WING. Milk and its products. New York: The Macmillan Co.,
1909.

CHAPTER XI.

ADULTERATION OF MILK.

Introduction. That milk is easily contaminated and subject
to deleterious changes, was well known in ancient times. This
is proved by a reference to the Talmudic Laws, where the fol-
lowing statement is found : ' ' Milk is one of the beverages that
makes the articles of food liable to receive impurities." (3)

It is true that chemical preservatives were not known at that
time and consequently were not used. Such materials, how-
ever, have been used for many years in milk intended for

human consumption and the practice prevails to some extent

\ .
at the present time.

It may be said that perhaps few questions concerning the
public health have provoked more discussion or been produc-
tive of more experiments and investigations than that of the
use of preservatives in foods intended for human consumption.
It is of more than passing interest, and certainly a matter of
congratulation, -to be able to say that the greater the advance of
science, the greater and more powerful is the ammunition
brought forward to fight, and successfully too, the advocates
of the use of deleterious materials in our food products. These
substances, as is well known, are added in many cases for the
purpose either of enhancing the value of poor products or
preventing or arresting the decay of an already unwholesome
food .

The literature abounds in records of investigations of the
influence of preservatives on the food value of milk. For a
very complete bibliography of this subject, the reader is re-
ferred to Kastle and Roberts (4).

Much has been written on both sides of this all-important
question. If proper care is exercised in the .handling of milk

188 ADULTERATION OF MILK.

intended for human consumption, there is no necessity for
the use of preservatives to insure its keeping fresh. This is
particularly to be emphasized in the care of milk to be fed to
infants and invalids.

While there is much evidence in favor of the use of some of
the preservatives for milk, such as boric acid or borax, formal-
dehyde, hydrogen peroxide, etc., yet most of this evidence is
the result of artificial digestion experiments. It is conceded
that such investigations are of great scientific value but too
much importance must not be attributed to them. There are
many conditions which obtain in the natural process of diges-
tion which cannot be duplicated under artificial conditions.
A notable instance of the necessity of conducting both the arti-
ficial and natural digestion experiments before drawing any
final conclusions is recorded by Wiley (6) in his report on the
influence of salicylic acid and salicylates on digestion and
health.

Wiley states in his conclusions :

' ' The data show very clearly that salicylic acid and salicylates appear
to exert an exciting influence upon the activities which take place in the
alimentary canal, stimulating the organs to greater effort, and this stim-
ulation leads at first to increased digestion and absorption of the foods
which are introduced into the stomach. In the light of the data which
are exhibited, salicylic acid may be said to increase the solubility and
absorption of the food in the alimentary canal, so that large parts of the
nutrients taken into the stomach actually enter the circulation.

"The data which show the effects just noted also indicate that the
general effect upon the system is depressing, in that the tissues are bro-
ken down more rapidly than they are built up, and thus the normal
metabolic processes are interfered with in a harmful way. The admin-
istration of the salicylic acid is attended by a gradual decrease in the
weight of the subjects, altho the quantity of food elements administered
during the preservative and after periods is slightly increased, which
fact, together with a greater degree of absorption of the food elements,
should have resulted in a slight increase in weight. This increase in
weight, however, does not occur, and the disturbing influences of the
salicylic acid upon metabolism, altho not very great, are specifically
demonstrated."

The natural inference from an artificial digestion experiment,
along the lines indicated, would be that salicylic acid is a

INTRODUCTION. 189

help rather than a hindrance to digestion of proteids, whereas
the inference from the natural digestion experiment is just the
reverse.

It is admitted, of cour.se, that it is almost impossible to con-
duct metabolism experiments with infants as subjects, and they
are the very class most concerned. Among the many experi-
ments carried on with very young animals are those of Annett
(l). The subject of his experiments were kittens three weeks
of age. The milk fed was treated with boric acid. The amounts
for the two experiments were respectively 40 and 80 grains of
boric acid per gallon of milk. At the end of the four weeks, all
kittens fed on. the adulterated milk were dead, while the con-
trol lot, which were fed pure milk, were alive and healthy.

This series of experiments was followed by a similar one,
the milk, however, being treated with formaldehyde in place of
boric acid. The results of the latter experiments were not so
conclusive as were those obtained from the boric acid test. At
the same time, the data obtained are of more than 'passing
interest. In the first experiment, the milk contained 7 parts
formaldehyde to 50,000 parts milk. In the second experiment,
the proportion of formaldehyde was just doubled, or 1 to 2.5,000.
In the third experiment, the proportion of formaldehyde was
again doubled, or 1 part to 12,500. It was noted that the gain
in weight in all three experiments by the control kittens receiv-
ing only pure milk was far ahead of the gain of those receiving
the adulterated article. This is particularly emphasized in the
third experiment. These results are at variance with many of
the findings recorded for artificial digestion experiments but as
they have stood the test of criticism and investigation they
must be accorded serious consideration.

It is perhaps gratifying to know that Annett 's views on this
subject are ably supported by the reports of Wiley (6) on the
influence of food preservatives and artificial colors on digestion
and health. The subjects of Wiley's experiments were all
healthy young men, and it was clearly shown that the preserv-
atives studied, viz., borax, salicylic acid, sulphites and benzoic
acid, and formaldehyde, were deleterious substances and pro-
duced digestive disturbances.

190 ADULTERATION OF MILK.

In view of the contradictory mass of evidence which is at
hand as shown by Kastle and Roberts (4), it would appear
that laws forbidding the use of preservatives in milk intended
for human consumption are certainly to be recommended as
safeguarding the public health. The strong, healthy stomach
may and can withstand strains to which the delicate digestive
organs of an infant or invalid would succumb.

Tests for preservatives. A complete examination of a sample
of milk for preservatives would include tests for boracic acid
and its compounds, formaldehyde, fluorids, benzoic acid and
its compounds, salicylic acid and salicylates, peroxide of hydro-
gen, etc. Such thorough analytical work can. be conducted
only in a well-equipped laboratory. It is assumed that the
man in charge of the work is an expert and has at his disposal
the necessary standard works describing the tests. For this
reason it is not considered necessary to reprint the methods for
making such determinations. The preservatives most com-
monly used are borax and formaldehyde. It is fortunate that
there are simple and reliable tests for these two.

Borax. A preliminary test may be made for boric acid and
borates by immersing a strip of turmeric paper in about 100 cc.
of milk to which about 7 cc. of concentrated hydrochloric acid
has been added. If boric acid or borax is present, the paper
on drying will acquire a peculiar red color which is changed by
ammonium hydrate to a dark blue-green but is restored by acid.
The above mentioned reagents can easily be obtained at a drug
store. A positive reaction would indicate the presence of
borax but a negative reaction might not in all cases mean that
the material does not contain borax but would require further
examination where better laboratory facilities could be ob-
tained.

Formaldehyde. This is without doubt the best preservative
of milk. So efficacious is this material that there are many
compounds to be found on the market under various names,
such as " callerine," " freezine," etc. These different prepar-
ations are weak solutions of formaldehyde, ranging from about
3% to 7% in strength.

\V. \TKKING OF MII.K. 191

There are two different methods which are easily carried
out, — those of Hehner and Leach.

Hchncr 's test for formaldehyde :

"To 10 cc. of milk in a wide test tube add about half the volume of
concentrated commercial sulphuric acid, pouring- the acid carefully down
the side of the tube so that it forms a layer at the bottom, without mix-
ing with the milk. A violet /.one at the junction of the two liquids indi-
cates formaldehyde. The coloration produced depends on the presence
of a very small amount of iron. For this reason the ordinary commercial
acid used in the Babcock test answers well for this test. However, if an
excess of formaldehyde is present in the milk, this test wTill not indicate
the presence of the preservative."

Leach' s test for formaldehyde :

"Commercial hydrochloric acid (specific gravity 1.2) containing 2 cc.
of 10 % ferric chloride per liter is used as a reagent. Add 10 cc. of the
acid reagent to an equal volume of milk in a porcelain casserole, and
heat slowly over the free flame nearly to boiling, holding the casserole
by the handle, and giving it a rotary motion while heating to break up
the curd. The presence of formaldehyde is indicated by a violet color-
ation, varying in depth with the amount present. In the absence of
formaldehyde, the solution slowly turns brown. By this test 1 part of
formaldehyde in 250,000 parts of milk is readily detected before the milk
sours. After souring, the limit of delicacy proves to be about 1 part in
50,000."

The porcelain casserole can be obtained at any chemical sup-
ply house and the solution as indicated can very easily be made
up by any druggist. In place of the gas flame, an alcohol
lamp may be used. A word of caution must be mentioned
with reference to this test, because it is so delicate. In at least
one instance the use of absorbent cotton in a strainer at a good
dairy resulted in the finding of formaldehyde in the milk.
Investigation showed that the cotton had been sterilized with
formaldehyde by the manufacturers. The use of formaldehyde
in the tubes of milking machines offers like possibilities for the
contamination of milk by this chemical.

Watering of milk. One of the more common sophistications
of milk is the addition of water. Such a practice is not only a
pecuniary fraud but it both lowers the nutritive value and
may prove at times to be a menace to health, as discussed in
Chapters III and V.

192 ADULTERATION OF MII«K.

The effect of the added water is to lower the specific gravity
and also the percentage of all the ingredients.

The determination of fat alone is not sufficient to indicate
in all cases whether or not water has been added to milk.
This could be illustrated by many instances, notably in the
case of Jersey milk containing 6% fat. Such milk could be
diluted with 50% water and at the same time yield 4f/f fat.
Judged by the fat content alone, the watered milk would be
considered of high quality, while the nutritive value would be
only two-thirds of the normal. Serious mistakes have been
made by modifying for infant feeding just such watered milk,
upon the assumption that it was a normal milk containing 4%
fat.

The determination of the specific gravity when the only
sophistication of the milk is that of added water, is of great
value. A low specific gravity, that is, below 1.028, with a low
fat content, is a very sure indication of added water. When
an inspector finds such conditions the sample should be exam-
ined by the immersion refractometer. Full directions for
using this instrument are to be found in Leach (5). A read-
ing below 39 indicates added water, between 39 and 40 the
sample is to be regarded as suspicious. If it is not possible to
have access to a refractometer a determination of milk sugar
will be very helpful. A low sugar content, that is, below
4%, in connection with a low gravity and fat, indicates added
water.

Skimming. The removal of the cream is to be considered
an adulteration in that the consumer is deceived and misled.
Evidence regarding whether or not a given sample of milk Jias
been skimmed is mainly gathered from results of the test for
fat. The only cases where this test is not reliable are to be
found in the rich milks of the Channel Island breeds, which
can be skimmed and still indicate a fat per cent, above many
of the legal standards.

Carbonate of soda. This and the bicarbonate are occasion-
ally used to lessen the acidity of old milk. The addition of
these compounds to milk is to be considered in that they are
added to conpeal inferiority. For detection, see Leach (5).

COLORING MATTER. 193

Thickening agents for cream. Gelatin is added to cream for
the purpose of increasing viscosity and giving the appearance
of greater richness than is really the case. For detection, see
Leach (5).

Sucrate of lime (viscogen) is sometimes used in order to
make pasteurized cream whip. It is a harmless adulteration
and permissible when the product is so labeled.

Heated milk. Storch has devised a test that will indicate
whether milk, cream or other dairy products have been heated
to 178° F. (80°C.). It is carried out as follows : A teaspoon-
ful of milk is poured into a test tube and one drop of a weak
solution of peroxide of hydrogen (2%) and two drops of a 2%
solution of paraphenyldiamin are added. The mixture is then
shaken. If a dark violet color appears at once, the milk has
not been heated, or at any rate, not above 175° F.

Coloring matter. The chief object of adding coloring matter
to milk is for the purpose of concealing either skimming or
watering. Two classes of compounds are used, vegetable and
coal-tar colors. Some of the latter are harmless, as naphthol
yellow S or Orange I, as declared in the U. S. Department of
Agriculture, Food Inspection Decision 76. Only a very small
amount of coloring matter is used and the effect is generally
harmless ; but such additions are in violation of the law in
that they tend to mislead and deceive the consumer. The
detection of added coloring matter in milk cannot very well be
undertaken away from a chemical laboratory. Full and com-
plete directions for the testing of milk for the presence of
added coloring matter will be found in Bulletin No. 107 (7).

If there is any suspicion that a milk has been adulterated
with coloring matter, it should be allowed to stand undis-
turbed for several hours in a glass vessel. If then the sample
exhibits different zones of color, it may safely be said that the
milk contains no added coloring matter. The different colors
should be the yellow of the cream, which overlies the stratum
of a mixture of milk and cream of a lighter color, under which
is the bluish layer of skimmed milk. If, on the other hand,
the color is more or less uniform throughout the sample, it
should be further examined for confirmation.

194 ADULTERATION OF MILK.

REFERENCES.

1. ANNETT. Boric acid and. formalin as milk preservatives. I^ancet,
Vol. II, 1899, p. 1282.

2. DOANK and PRICK. Influence of preservatives on food value of
milk. Bui. Xo. 86, Maryland Agr. Exp. Sta., College Park, Md., 1902.

3. Jewish Encyclopedia, Vol. VIII, 1904, p. 591.

4. KASTLE and ROBERTS. The chemistry of milk. Bui. Xo. //.
Hyg. Lab., U. S. Pub. Health and Mar. Hasp. Sen1., Washington,
D. C., 1908, p. 309.

5. IvEACH. Food inspection and analysis. New York : John Wiley
& Sons, 1906.

6. WilyEY. Influence of food preservatives and artificial colors on
digestion and health. liul. Aro. 84, Bur. Chon., l\ S. Dcpt. Agr.,
Washington, D. C., Part I, 1904; Part II, 1906.

7. WiivEY (EDITOR). Official and provisional methods of analysis,
Association of Official Agricultural Chemists. Bui. Xo. 107 (revised'},
Bur. Chem., U. S. Dept. Agr., Washington, D. C., 1908.

APPENDIX A.

DAIRY ORDIXANCK OF BKRKKLKY,

ORDINANCE No. 495 — A.

Providing for the Inspection of Milk, Dairies and Dairy Herds, and Regu-
lating the Sale- and Disposition of Milk in the Town of Berkeley, and
Providing a Penalty for the Violation of Said Ordinance.

Be it ordained by the Board of Trustees of the Town of Berkeley, as
follows :

Sec. 1. From and after October 10, 1907, no person shall offer or ex-
pose for sale, or sell or deliver for sale or consumption within the Town
of Berkeley any milk or cream, without first obtaining and having a
permit therefor from the Health Officer in accordance with the condi-
tions in this ordinance hereinafter provided.

Sec. 2. Any person desiring a permit to engage in the sale or disposi-
tion of milk, as provided in Section 1 hereof, shall first make application
therefor, to the Health Officer of the Town of Berkeley by filing with
the Health Officer an application in writing therefor, which said appli-
cation shall set forth with reasonable exactness the name and place of
residence of the applicant, the exact location or place from which the
applicant obtains or is to obtain his milk, and if the applicant is no4L a
producer of milk, then the name of the person or persons from whom he-
obtains or is to obtain his milk for sale or distribution, and if said appli-
cant is a producer of milk, the number of cows in his dairy 'herd, or if
he is not a producer' of milk, the number of cows in the dairy herd of
the person or persons from whom he obtains or is to obtain his milk ;
there shall also be filed with the Health Officer the veterinary surgeon's
certificate required by Section 6 of this ordinance concurrently with the
application heretofore mentioned ; and said application shall further set
forth the manner in which the applicant intends to dispose of his milk
when granted such permit, according to the provisions of this ordinance,
and shall be signed by the applicant, and when received by the Health
Officer shall be placed on file and the name of the applicant shall In-
registered in a took of registration kept for such purpose.

Sec. 3. Any such applicant, or any person from whom such appli-
cant obtains, or is to obtain his milk, shall permit the Health Officer of
the Town of Berkeley, his assistants and deputies, to inspect the dairy
and the dairy herds of such applicant, or the dairy and dairy herd of
the person, or persons, from whom the applicant obtains, or is to obtain

196 APPENDICES.

his milk, by physical examination and the tuberculin test of the cows
for the purpose of determining the presence or absence of tuberculosis,
together with all appliances and milk vessels used therein, and any
refusal upon the part of such applicant, or upon the part of the person
or persons from whom such applicant obtains or is to obtain his milk, to
permit the inspection above referred to shall be deemed a sufficient
ground upon which the Health Officer may refuse to issue the permit
applied for, and for such cause may revoke the same after its issuance.

Sec. 4. It shall thereupon be the duty of the Health Officer to issue
a permit or permits to sell or distribute milk within the corporate limits
of the Town of Berkeley to each applicant who has complied with the
requirements of this ordinance, which said permit shall be numbered
and signed by the Health Officer, and a record thereof shall be kept in
the book of registration provided for in Section 2 hereof, and said permit
shall be valid and effective for the period of one year from and after the
date of its issuance, unless sooner revoked by said Health Officer for
violation of any of the provisions of this ordinance.

Sec. 5. Bach person granted a permit under the provisions of this
ordinance shall cause his name and his place of business and the num-
ber of his permit to be legibly placed in a conspicuous place on the outer
side of all carriages, wagons or other vehicles used by him in the sale
or distribution of milk within the corporate limits of the Town of Berke-
ley, and all persons who sell milk from stores or shops shall keep their
permit constantly posted in a conspicuous place upon the wall of the
room within wrhich such sale of milk is prosecuted or carried on.

Sec. 6. No person shall bring into the Town of Berkeley for sale,
either by wragon, cart, train or any other kind of vehicle, or keep, have
or offer for sale, or sell in said towyn, any milk or cream contained in.
cans, bottles or packages unless such cans, bottles and packages contain-
ing such milk or cream for sale shall be marked writh a legible stamp,
tag or impression bearing the name of the owner of the cows from which
such milk was drawn, giving his place of business, including name of
city, street and number, and unless the owrner or owners of such cows
shall first file in the office of the Health Officer a certificate of a duly
licensed veterinary surgeon, stating that such cows have been subjected
to a physical examination and the tuberculin test for the purpose of
detecting the presence or absence of tuberculosis, and shall state the
results of his examination of them writh reference to the existence of
other infectious or contagious diseases. Such certificate shall give a
number which has been permanently attached to each cow and shall
state the date, the place of examination, the temperature of the cow or
cows at intervals of three hours for twyelve hours before the subcutane-
ous injection of the tuberculin, the temperature at the tenth hour after
the injection of the tuberculin, and every three hours after the aforesaid
tenth hour, for twelve hours, or until the reaction is completed. The

APPENDIX A. 197

said certificate shall further contain the conclusions of the veterinary
surgeon touching the presence or absence of tuberculosis in the animal
or animals examined, drawn from the data afforded by the physical
examination and the tuberculin test. Said certificate shall be accom-
panied by a description of the animal or animals tested, sufficiently
accurate to serve for purposes of identification.

Sec. 7. No milk which is watered, adulterated, reduced or changed in
any respect by the addition of water or other substance or by the
removal of cream, or milk which has been drawn from cows suffering
from tuberculosis or any other contagious disease, or milk which has
been drawn from cows which have not been inspected by a duly licensed
veterinary surgeon and tested by physical examination and the tubercu-
lin test for the purpose of detecting the presence or absence of tubercu-
losis, shall be brought into the Town of Berkeley, or held, kept, sold or
offered for sale at any place in said town, nor shall any person, persons
or corporation keep, have, sell or offer for sale any such milk in said
Town of Berkeley, except that milk from which any part of the cream
has been removed may be sold in the manner hereinafter provided.

The term "adulterated milk," as used in this ordinance, means:

First — Milk containing more than eighty-eight per centum of water
fluids.

Second — Milk containing less than twelve (12) per centum of milk
solids.

Third — Milk containing less than three (3) per centum of fats.

Fourth — Milk drawn from animals within fifteen (15) days before or
five (5) days after parturition.

Fifth — Milk drawn from animals fed on any .substance in a state of
fermentation or putrification or on any unwholesome food.

Sixth — Milk drawn from cows kept in a crowded or unhealthy condi-
tion, or from cows suffering with tuberculosis or any other contagious
disease.

Seventh— Milk from wrhich any part of the cream has been removed.

Eighth — Milk w7hich has been diluted with water or any other fluid,
or to which has been added, or into which has been introduced, any for-
eign substance whatever.

Sec. 8. The Health Officer is hereby authorized to provide metal ear
tags each marked with the words, " Berkeley Board of Health," and a
serial number, and also to provide printed blanks, and is authorized to
distribute them to any duly licensed veterinary surgeon who may apply
for them for use in compliance with the requirements of Section 6 of
this ordinance.

Sec. 9. Notwithstanding the provisions of Section 7 of this ordinance,
milk from which the cream has been removed, if such milk is otherwise
wholesome and unadulterated, may be sold as skimmed milk by dealers
having the permit provided for by this ordinance, but only from vessels

198 APPENDICES.

legibly marked, in addition to the stamp, tag, or impression provided
for in Section 6 of this ordinance, with the words "Skimmed Milk" in
plain black letters upon a light background, and each letter being at
least one inch high and one-half inch wide, the said words being placed
in a conspicuous place on the top or side of such vessel.

Sec. 10. Any adulterated milk which has been brought into the Town
of Berkeley, or is held and offered for sale in said town, excepting
skimmed milk when offered for sale as provided in this ordinance, may
be seized and destroyed by an inspector or other officer of the Board of
Health of said town authorized to inspect the same.

Sec. 11. No cream which is adulterated, or that shall contain less
than twenty (20) per centum of fat, shall be brought into the Town of
Berkeley, or held, kept, sold or offered for sale in said town, nor shall
any one keep, have, sell or offer for sale in said town any such cream.
The term "cream " means the fatty portions of pure milk which rise to
the surface when milk is left at rest, or which are separated by other
means. The term "cream which is adulterated," as used in this sec-
tion, means any cream to which any foreign substance has been added.

Sec. 12. The Health Officer and his assistants and deputies shall have
authority to stop and inspect, or cause to be inspected, any wagon, cart,
train or other vehicle used in delivering milk, or any store, depot, shop,
creamery or any place where milk is offered for sale or sold, and to take
samples of milk from wagons, carts, trains or any other place where
milk is sold or offered for sale, for the purpose of enforcing the provis-
ions of this ordinance.

Sec. 13. Milk must not be kept for sale or stored in any stable, or
milk-house that is connected with a stable, or in any room used for
sleeping or domestic purposes or opening into same, nor in unclean or
rusty cans.

Milk must not be transferred from cans to bottles or other vessels on
streets or at railroad depots. Milk must not be sold in bottles, except
under the following rules :

Bottles must be washed clean with hot wrater solution of soap or soda,
or some other alkali, and then with hot water before filling.

Bottles must not be filled except at the dairy or creamery, and in the
town only in rooms .so situated as to prevent contamination of the milk
by dust or other impurities from the streets or elsewhere.

Bottles must not be washed or filled with milk in any rooms used for
sleeping or domestic purposes, or opening into the same.

The vessels in which milk is kept for sale must be protected by means
of a suitable covered receptacle and so placed in the store as to prevent
dust from the street or other impurities falling into it.

All cattle condemned as tuberculous shall be removed from the prem-
ises within one week thereafter.

APPENDIX A. 199

When any person having a permit hereumler shall sell or deliver to
any customer any tickets or tags representing any milk or cream to
which the customer is entitled, the same shall be in the form of coupon
tickets, or be metal tags, so as to insure cleanliness.

Sec. 14. Nothing herein contained shall be construed to prevent or
prohibit the use, sale or manufacture of what is known as condensed
milk, or what is known as buttermilk, provided the same are made, com-
pounded and prepared from milk not lower than the standard provided
in this ordinance, and provided further that said condensed milk or
buttermilk are in sound, wholesome condition, and provided also that in
the case of condensed and dried milks, the properties of milk solids
shall be equivalent to twelve (12) per centum of milk solids in crude
milk, and that of such solids twenty-five (25) per centum shall be fat.

Sec. 15. Any person who shall violate any of the provisions or
requirements of this ordinance shall be deemed guilty of a misdemeanor
and upon conviction thereof, shall be punished by a fine of not less than
ten (10) dollars, nor more than two hundred and fifty (250) dollars, or by
imprisonment in the county jail of Alameda county for not more than
ninety (90) days; or by both such fine and imprisonment.

The judgment imposing the fine may provide for its collection by im-
prisonment in the county jail of Alameda county for the time and in the
manner provided by law.

Sec. 16. All ordinances and parts of ordinances in conflict with the
provisions of this ordinance are hereby repealed.

Sec. 17. This ordinance shall take effect and be in force and effect
from and after its final passage.

Sec. 18. This ordinance is hereby ordered to be printed and pub-
lished (with the ayes and noes) for two days in the Berkeley Daily
Gazette. which newspaper is hereby designated for that purpose.

APPENDIX B.

CHICAGO TUBERCULIN TEST ORDINANCE AND RULES OF THE
DEPARTMENT OF HEALTH.

ORDINANCES REQUIRING TUBERCULIN TEST OF ALL Cows SUPPLYING
MILK AND MILK PRODUCTS.

Be it ordained by the City Council of the City of Chicago :

MILK.

SECTION 1. No milk, cream, buttermilk or ice cream shall be sold,
offered for sale, exposed for sale or kept with the intention of selling
within the City of Chicago after January 1, A. D. 1909, unless such milk
or cream or the milk or cream contained in buttermilk and ice cream,
be obtained from cows that have given a satisfactory negative tuberculin
test within one year ; the cows having been satisfactorily tested shall be
marked "tuberculin tested" and shall be numbered and a certificate
shall be filed with the division of milk inspection of the Department of
Health of the City of Chicago upon forms furnished by the Commissioner
of Health, giving the number, a brief description of the animal, the date
of the taking of said test and the name of the owner. Said certificate
shall be signed by the person making such test ; provided, however, that
from January 1, 1909, for a period of five years, to wit, until January 1,
1914, milk or cream or buttermilk and ice cream made from milk or
cream, obtained from cows not tuberculin tested or not free from tubercu-
losis, may be sold within the City of Chicago if the milk or cream from
said cows is pasteurized according to the rules and regulations of the
Department of Health of the City of Chicago.

SECTION 2. Any milk, cream, buttermilk or ice cream offered for .sale,
exposed for sale or kept with the intention of selling within the City of
Chicago wThich shall be found within the City in violation of Section 1,
shall be forthwith seized, condemned and destroyed by the milk and
food inspectors or other duly authorized agents or employes of the De-
partment of Health of the City of Chicago.

SECTION 3. This ordinance shall be in full force and effect from and
after January 1, 1909.

BUTTP:R.
Be it ordained by the City Council of the City of Chicago :

SECTION 1. No butter shall be sold or offered for sale or kept with
the intention of selling in the City of Chicago after January 1 , 1909, un-

APPENDIX B. 201

less such butter be made from milk or cream obtained from cows that
have given a satisfactory negative tuberculin test within one year ; pro-
vided, however, that from January 1, 1909, for a period of five years, to
wit, until January 1, 1914, butter made of milk obtained from cows not
tuberculin tested or not free from tuberculosis may be sold in the City
of Chicago if the milk or cream from which such butter was made was
pasteurized according to the rules and regulations of the Department of
Health of the City of Chicago.

SUCTION 2. It shall be unlawful to sell any butter in the City of
Chicago, unless there be stamped on the package in plainly legible let-
ters of not less than one-eighth-inch type : ' ' Made of milk (or cream)
from cows free from tuberculosis as shown by tuberculin test, ' ' or, "Made
from milk (or cream) pasteurized according to the rules and regulations
of the Department of Health of the City of Chicago."

SKCTION 3. Any butter offered for sale, exposed for sale or kept with
the intention of selling in the City of Chicago, which shall be found
within the city in violation of this ordinance, shall be forthwith sei/ed,
condemned and destroyed by the milk and food inspectors or other duly
authorized agents or employes of the Department of Health of the City
of Chicago.

SKCTION 4. This ordinance shall be in full force and effect from and
after January 1, 1909.

CHEESE.

Be it ordained by the City Council of the City of Chicago :

SKCTION 1. No domestic cheese shall be sold or offered for sale or
kept with the intention of selling in the City of Chicago after January 1,
1909, unless .such cheese be made from milk or cream obtained from
cows that have given a satisfactory negative tuberculin test within one
year ; provided, however, that from January 1, 1909, for a period of five
years, to wit, until January 1, 1914, domestic cheese made of milk obtained
from cows not tuberculin tested or not free from tuberculosis, may be
sold in the City of Chicago if the milk or cream from which such cheese
was made was pasteurized according to the rules and regulations- of the
Department of Health of the City of Chicago.

SKCTION 2. It shall be unlawful to sell any such cheese in the City
of Chicago unless there be stamped on the package in plainly legible
letters of not less than one-eighth-inch type : " Made of milk (or cream)
from cows free from tuberculosis as shown by tuberculin test, " or ' ' Made
from milk (or cream) pasteurized according to the rules and regulations
of the Department of Health of the City of Chicago."

SECTION 3. Any cheese offered for sale, exposed for sale or kept with
the intention of selling in the City of Chicago, which shall be found
within the citv in violation of this ordinance, shall be forthwith seized,

202 APPENDICES.

condemned and destroyed by the milk and food inspectors or other duly
authorized agents or employes of the Department of Health of the City
of Chicago.

SECTION 4. This ordinance shall be in full force and effect from and
after January 1, 1909.

RULES RKGUI.ATING THE TUBERCULIN TESTING OF Cows.

Rule 1. Who May Make the Test.] Tuberculin tests made on ani-
mals supplying the City of Chicago with milk or milk products may be
made by licensed graduate veterinarians, federal or state veterinarians,
federal, state or city dairy and milk inspectors and by persons regularly
employed by the Chicago Department of Health for that purpose.

Rule 2. The Test to be Employed.] The regular injection method
of tuberculin testing shall be employed. The temperature shall be
taken at least four times on the da}- preceding the inoculation, and at
least six times on the day following the inoculation, at not less than two
hour intervals. A rise of two degrees over the average temperature on
the day preceding the inoculation shall be considered a positive test.
If a rise of from one and a half to two degrees is obtained, the results
shall be considered doubtful, and the animal subjected to a later retest.
Animals that have been added to the herds within the last six weeks
shall be tested by the ordinary injection test supplemented by Cal-
mette's Ophthalmic Test, and a positive result with either one or the
other shall condemn the animal. The Department of Health shall have
the power to require the retesting of all animals submitted for milk sup-
ply by the Calmette Ophthalmic method or any other method to be
decided on in the future.

Rule 3. The Numbering and Tagging of Animals.] All tested ani-
mals shall bear an indestructible tag indicating the series, and also the
number assigned to the animal. Tags placed by federal, state and
municipal inspectors will designate by abbreviations or otherwise the
series represented. Veterinarians supplying the numbered tags must
have their initials or some other distinctive mark appear on the tag with
the number to indicate the series.

Rule 4. Statement to be Submitted.] A statement must be filed with
the Division of Milk Inspection for every tuberculin tested animal sup-
plying the City of Chicago with milk or milk products. This statement
must indicate the number and series given to the animal, which number
and series must correspond with the tag or mark worn by the animal.
This statement must also state the age and color of the animal, and any
other distinctive marks shown by the animal. In addition the statement
must show the temperature, record of the animal on the days preceding
and following the test, the date and the exact time of taking these

APPENDIX B. 203

.temperatures and the date and time of making the injection and amount
and kind of tuberculin used ; the name of the owner and the signature of
the person making- the test, together with the official capacity of said
person or persons making the test, and their address. The statement
submitted shall also indicate the date of the last tuberculin test made
upon the animal and the method of making this test, and the length of
time that the animal has been in the herd.

Rrucs REGULATING THE PASTEURIZING OF MILK AND MILK PRODUCTS.

The following rules shall regulate the pasteurizing of milk and milk
products offered for sale, exposed for sale or kept with the intention of
selling within the City of Chicago, after January 1st, A. D. 1908:

Rule 1. Milk" and Skimmed Milk.] Milk and skimmed milk shall
not contain more than 100,000 bacteria per cubic centimeter from May
1st to September 30th, and not over 50,000 bacteria per cubic centimeter
between October 1st and April 30th.

Rule 2. Cream and Ice Cream.] Cream and icecream shall not con-
tain more than 200,000 bacteria per cubic centimeter from May 1st to
September 30th, and not over 100,000 bacteria per cubic centimeter
between October 1st and April 30th.

Rule 3. Milk, Skimmed Milk, Buttermilk, Cream and Ice 'Cream.]
An original package of pasteurized milk, skimmed milk, buttermilk,
cream or ice cream, exposed to the temperature of the room for 48 hours
and stoppered with a sterile cotton plug, shall not show evidences of
putrefaction, after being so exposed.

Rule 4. Skimmed Milk and Ice Cream.] Skimmed milk and ice
cream shall give a negative test when treated in the following manner :

To 5 cc. of the pasteurized product add two drops of a 2 per cent solu-
tion of paraphenylenediamin, and one drop of a 2 per cent solution of
hydrogen peroxide, and agitate.

Not more than a tinge of blue shall be obtained by this test within 30
seconds after mixing.

Rule 5. Butter.] Butter shall respond to the following test:

25 grams of pasteurized butter placed in a small beaker and heated by
being placed in water at 60 degrees centigrade, the clear butter fat then
poured off and the remaining liquid then diluted with an equal volume
of water. The mixture thus obtained is now treated with two drops of
a 2 per cent solution of paraphenylenediamin and one drop of a solution
of 2 per cent hydrogen peroxide.

When thus treated not more than a perceptible blue color shall be
obtained within 30 seconds after mixing.

Rule 6. Pasteurizing Temperatures.] All pasteurized milk, cream,
skimmed milk, milk products, and milk and cream used in the produc-

204 APPENDICES.

tion of milk products shall be pasteurized in accordance with the follow-
ing regulations :

(A) Continuous Pasteurization.] In all continuous pasteurization the
milk and cream shall be heated to a temperature which shall be deter-
mined and fixed by the Department of Health for each machine at a
point corresponding to the temperature required to kill 99 per cent of
the bacteria and all pathogenic bacteria contained in the raw product.
For this determination ordinary raw milk containing in the neighbor-
hood of 3,000,000 bacteria shall be used and the pasteurized product shall
be collected as it flows from the cooling apparatus.

All continuous pasteurizers shall be equipped with a feeding pipe
which is so constructed that the pasteurizer cannot be fed in excess of
its normal w-orking capacity ; that is, in excess of the working capacity
of the machine at which 99 per cent of the bacteria are killed when the
required amount of heat is applied.

All continuous pasteurizers operated outside of the city limits, for the
production of pasteurized milk and milk products to be sold in the City
of Chicago shall be equipped with an apparatus regulating automatically
the supply of steam and heat, so as to correspond with and produce the
required temperature of the outflow of the pasteurized product. These
automatic thermo regulators shall be accurate and must be approved by
the Commissioner of Health before being installed.

A recording apparatus shall be installed upon all continuous pasteur-
izers operated within the city limits so as to record during operation the
temperature of the pasteurized product as it flows from the heater. The
thermometer of this recording apparatus must be accurate and kept
emerged in the milk in such a way that it is not exposed to escaping
steam or other heat, except the heated milk.

The records made by this recording thermometer must be accurate and
made in a chamber which is kept under lock and key in the control of
the Department of Health.

The automatic thermo regulating and recording apparatus may be com-
bined into one instrument and it is recommended that all pasteurizers be
equipped with both appliances or the combination apparatus.

(B) Held Pasteurization.] Whenever milk is held during pasteuri-
zation in such a manner that the process of pasteurizing is not a contin-
uous one, namely, a continuous flow of milk through the heating or heat
retaining chamber, the process shall be designated as ' ' Held Pasteuriz-
ation." Such methods of pasteurization and pasteurization appliances or
systems installed and used shall be examined and approved by the Com-
missioner of Health, or his duly appointed representatives, when all of
the following requirements are fulfilled :

1. When the pasteurized product shows that over 99 per cent of the
bacteria and all pathogenic bacteria contained in the raw product have
been destroved.

APPENDIX B. 205

2. When the mechanism of the pasteurizer or pasteurizing system is
such that the three important elements, namely : the temperature, time
of exposure, and the quantity of milk exposed at one time can be readily
kept under control and observation by the Department of Health.

3. When the following conditions are complied with :

A uniform heating of 140 degrees F. maintained for 20 minutes ; 150
degrees F. maintained for 15 minutes ; 155 degrees F. maintained for 5
minutes; 160 degrees F. maintained for ll/2 minutes; 165 degrees F.
maintained for 1 minute.

The time shall be calculated from the period that the entire quantity
reaches the required temperature.

Rule 7. Cooling Temperatures.] The pasteurized product shall be
cooled at once to a temperature of 45 degrees F. or less. This cooling
shall be so conducted that the pasteurized product is not exposed to the
air or other contamination. This cooling apparatus shall be so con-
structed that it can be readily cleaned and sterilized.

APPENDIX C.

DULUTH MILK ORDIXAXCK.

Ax ORDINAXCK.TO PROVIDE FOR THE INSPECTION OF MII.K, DAIRIES

AND DAIRY HERDS AND TO -LICENSE AND REGI'LATE THE SALE

AND DISPOSITION OF MII.K IN THE CITY OF DCI.UTH.

The Common Council of the City of Duluth do ordain as follows :

Section 1. That from and after the passage and approval of this ordi-
nance no person shall engage in the sale or disposition of milk within
the City of Duluth without first having obtained a license so to do in the
manner hereinafter provided.

Section 2. Any person desiring a license to engage in the sale or dis-
position of milk, as provided in section 1 hereof, shall first make appli-
cation therefor to the Common Council by filing with the commissioner
of health of the City of Duluth for presentation by him to the Common
Council of said city, an application in writing therefor, which said appli-
cation shall set forth with reasonable exactness the name and place of
residence of the applicant, the exact location or place from which the
applicant obtains or is to obtain his milk, and if the applicant is not a
producer of milk, then the number of cows in his dairy herd, the name
of the person or persons .from whom he obtains or is to obtain his milk
for sale or distribution, and if said applicant is a producer of milk, or if
he is not a producer of milk, the number of COWTS in the dairy herd of
the person or persons from wThom he obtains or is to obtain his milk ;
and said application shall further set forth the manner in which the
applicant intends to dispose of his milk wThen licensed, according to the
provisions of this ordinance, and shall be signed by the applicant, and
when received by the commis'sioner of health shall be placed on file and
the name of the applicant shall be registered in a book of registration
kept for such purpose.

Section 3. The filing of the application provided for in the next pre-
ceding section shall authorize the applicant to engage in the sale or dis-
posal of milk and to continue in the prosecution of that business, if he
shall, at the time of the filing of the application, be engaged in the busi-
ness of selling or distributing milk, until the Common Council takes
action thereon and either issues a license to the applicant or refuses so
to do.

Section 4. Any such applicant, or any person from whom such appli-
cant obtains or is to obtain his milk, shall permit the officers of the

AIM'KNDIX C. 207

department of health of the City of Duluth to inspect the dairy and dairy
herds of such applicant, or the dain- and dain- herd of the person or
persons from whom the applicant obtains or is to obtain his milk, to-
gether with all appliances and milk vessels used therein, and any refusal
upon the part of such applicant or upon the part of the person or per-
sons from whom such applicant obtains or is to obtain his milk to permit
the inspection above referred to shall be deemed a sufficient ground
upon which the Common Council may refuse to issue the license applied
for.

Section 5. Upon the filing of the application with the commissioner
of health, as provided in section 2 thereof, said commissioner, or an
authori/.ed inspector or veterinary, acting" under his instructions, shall
proceed, without unnecessary delay, to inspect the dairy and dairy herd
of such applicant, or the dairy and dairy herd of the person or persons
from whom the applicant obtains or is to obtain his milk for sale or dis-
tribution within the corporate limits of the City of Duluth, and it shall
be the duty of said commissioner of health to make or cause to be made,
under his direction and supervision, an examination and inspection, not
only of each and even- animal producing milk for sale or consumption
within the corporate limits of said City of Duluth, belonging to or con-
trolled by the said applicant or the person from whom said applicant
obtains or is to obtain his milk, but also of each and every COWT, heifer,
bull, steer or calf over the age of six months in the dairy or dairy herd
of such person, for the purpose of detecting the presence or absence of
tuberculosis or any other contagious or infectious disease, and said com-
missioner of health, or his said authorized inspector, acting under his
direction and supervision in making such inspection and examination, is
hereby authorized to use what is commonly known as the tuberculin test
as a diagnostic agent for the detection of tuberculosis.

Section 6. After such examination and inspection of the dairies and
dairy herds as in the next preceding section provided, an authorized
agent of the department of health of the City of Duluth shall tag each
and every animal so examined, which tag shall be of such character as
to afford a permanent record of such examination, nor shall such tag be
altered, mutilated or removed by any one other thai! an authorized agent
of the health department of the City of Duluth, and the result of the
same as regards the presence or absence from an infectious or contagious
disease, and immediately thereafter and without undue or unnecessary
delay the commissioner of health shall present the application in section
2 hereof provided for to the Common Council of the City of Duluth, and
shall accompany it with a report which shall contain the result of the
examination and inspection of the dairy and dairy herd of the applicant,
or of the dairy and dairy herd of the person or persons from whom the
applicant obtains or is to obtain his milk for sale or distribution within
the corporate limits of the City of Duluth ; and the commissioner of

208 APPENDICES.

health shall also state in such report what disposition, if any, has been
made by the applicant or the person or persons from whom the applicant
obtains or is to obtain his milk of the animals which were found to be
affected with tuberculosis or any other contagious or infectious disease,
if any there were, and wrhether or not an}- animals so diseased are used
by the applicant or the person or persons from whom the applicant ob-
tains or is to obtain his milk for the production of milk for sale or dis-
tribution for consumption within the corporate limits of the City of
Duluth.

Section 7. The Common Council shall thereupon, after proper investi-
gation, whether from a consideration of .such report or from other sources,
adjudge and determine what applicants may be entitled to obtain a
license for the sale or distribution of milk within the corporate limits of
the City of Duluth, and shall thereupon by resolution grant the license
applied for to such of the applicants as ma}- be, in the opinion of the
Common Council, entitled thereto under the provisions of this ordinance.

Section 8. It shall thereupon be the duty of the commissioner of
health, upon due notice from the city clerk of the passage of the resolu-
tion or resolutions in the next preceding section provided for, to issue a
license or licenses to sell or distribute milk within the corporate limits
of the City of Duluth to each applicant named in such resolution or reso-
lutions as is entitled thereto, which said license shall be numbered and
signed by the commissioner of health, and a record thereof shall be kept
in the book of registration provided for in section 2 hereof, and said
license shall be valid and effective for the period of one year from and
after the date of its issuance, and no longer.

Section 9. Each licensee shall cause his name and his place of busi-
ness and the number of his license to be legibly placed in a conspicuous
place on the outer side of all carriages, wagons, sleighs or other vehicles
used by him in the sale or distribution of milk within the corporate
limits of the City of Duluth, and all licensees who sell milk from stores
or shops shall keep their licenses constantly posted in a conspicuous
place upon the wall of the room within which such sale of milk is prose-
cuted or carried on.

Section 10. No person shall offer or expose for sale, or sell or dis-
tribute or deliver for sale or consumption any unclean, impure, unhealthy,
unwholesome or adulterated milk, and no person shall keep animals for
the production of milk for sale or distribution within the corporate limits
of the City of Duluth in an over-crowded condition, or in barns or stables
or other buildings which are not properly ventilated, or which are in an
unfit and unclean condition from any cause, nor shall any person draw
or suffer to be drawn milk from animals which are themselves in an
unfit or unclean condition, or from animals which are affected with
tuberculosis, or any other form of disease, or from animals which are fed
either wholly or in part upon fermented distillery waste or decomposed

APPKNDIX C. 209

brewery grains or the waste- of vinegar factories, in a fermented condi-
tion, or upon any other form of food which is calculated to produce milk
which is unhealthy or unwholesome, or from animals which are supplied
with water which is impure and unwholesome, nor shall any person
keep or suffer to he kept any milk or milk product intended for sale or
distribution in unfit or unclean vessels, nor in any unfit or unclean room
or building, or in any room or building used as a sleeping apartment
or for am other purpose incompatible with the proper preservation of
.the cleanliness, wholesomeness or healthy condition of the milk or milk
vessels kept therein, and all milk thus kept or produced is hereby de-
clared to be unclean, impure, unhealthy and unwholesome milk, within
the meaning of this section, and any milk which is shown by analysis to
contain a preservative or any other substance or substances of any char-
acter whatever not natural or normal constituents of milk, or to have
been deprived either wholly or in part of any constituent naturally or
normally contained in milk, or which is shown to contain more than
eighty-seven (87) per cent of water fluids, or less than thirteen (13) per
cent of milk solids, of which less than three and a half (^/4) per cent
shall be fat, is hereby declared to be adulterated milk within the mean-
ing of this section, and any such unclean, impure, unhealthy, unwhole-
some or adulterated milk may be sei/.ed and confiscated by the commis-
sioner of health or his duly appointed, qualified and authorized inspectors.

Section 11. No person shall, within the corporate limits of the City of
Duluth, have in his possession wTith intent to sell, offer or expose for
sale, or sell or deliver for sale or consumption, in any store or place of
business, or from any wagon, sleigh, cart or other vehicle used in the
distribution or sale of milk, any milk from which the cream has been
removed, or milk commonly known as "skimmed milk," without first
marking the can or package containing said milk and from which said
milk is delivered to the purchaser or customer with the words "skimmed
milk" in large, plain letters, each letter being at least one inch high
and a half inch wide, and to be placed in such position as to be easily
seen when such milk is sold and delivered.

Section 12. In order to carry out the provisions and purposes of this
ordinance, the commissioner of health, and all other officials, inspectors
and employes of the department of health in the City of Duluth, shall
have the right at any and all times to enter upon or in the premises of
any person licensed under the provision of this ordinance, to examine
and inspect the dairy and dairy herd of such licensee, and to appropriate
a reasonable amount of any milk or milk product in the possession or
under the control of such licensee for the purpose of use as samples and
for inspection or test, and they shall also have the right to enter upon
or into the premises of any person or persons from whom such licensee
obtains his milk for sale, to inspect and examine the dairy and dairy
herd of such person or persons ; and each licensee, under the terms

210 APPENDICES.

hereof, shall give at least three days notice in writing to the commissioner
of health of an intention on his part to obtain his milk from other per-
sons than those named in his original application, and any failure upon
his part so to do, or any refusal upon the part of said licensee or upon
the part of the person or persons from whom said licensee obtains his
milk, to allow such entry or inspection as may be required under the
terms of this ordinance shall be followed by an immediate revocation of
the license of such person or persons by the commissioner of health.

Section 13. It shall be the duty of the commissioner of health to cause
the dairy and dairy herd of all licensees hereunder, and the dairies and
dairy herds of the person or persons from whom such licensees obtain
their milk, to be inspected from time to time, and if the conditions
which are required as a prerequisite to obtaining a license under the
provisions of this ordinance are not constantly maintained, then it shall
be the duty of the commissioner of health to report the same to the
Common Council and make such recommendations in regard thereto as
he may deem proper.

Section 14. The commissioner of health may appoint, at such com-
pensation as may be fixed upon and determined by the Common Council,
such additional inspectors or employes as may be necessary for the pur-
pose of carrying out the provisions of this ordinance, and the salaries of
such additional inspectors and other expenses incidental to the enforce-
ment of this ordinance shall be payable out of the general fund, and it
is hereby made the duty of the commissioner of health to enforce the
provisions hereof.

Section 15. Any person violating any of the provisions of this ordi-
dance shall, upon conviction thereof, be punished by a fine of not less
than Ten (10) Dollars nor more than Thirty (30) Dollars, or by imprison-
ment for not less than ten (10) nor more than ninety (90) days, and
by the revocation of any license which may have been granted to such
persons under the terms of this ordinance, such revocation to be immedi-
ately made by the commissioner of health of the City of Duluth.

Section 16. All ordinances or parts of ordinances inconsistent here-
with are hereby repealed.

Section 17. This ordinance shall take effect and be in force from and
after its passage and publication.

Passed Dec. 5, 1904. M. B. CUU.UM,

Approved Dec. 7, 1904. Mayor.

Attest :

H. W. CHEADI.E, Citv Clerk.

APPENDIX D.

BLANK FOR REPORTING EXISTENCE OF INFECTIOUS

DISEASES.

DEPARTMENT OF HEAI/TH, THE CITY OF NEW YORK.

Report of Dairymen to be Filled Out and Delivered at Creamery Every
Saturday Morning.

Date....
To the Manager :

..Creamery.
.Town.
...State.
Sir:

In accordance with the requirements of the Board of Health of the
Department of Health of the City of New York in relation to infectious
disease* among milk handlers, I make the following1 statement upon my
honor.

Owner of Farm...
Operator of Dairy....
Location

No. of Persons in Family No. of Persons in Households of

Farm Hands.. No. of "Summer Boarders"

There are no cases of infectious diseases among any of the above men-
tioned persons, except as hereinafter stated.

NAME OF PATIENT. DISEASE. ATTENDING PHYSICIAN.

Respectfully,

The following infectious diseases are to be reported :

Measles Varicella (Chicken Pox) Erysipelas

Rubella (German Measles) Diphtheria Whoopinyr Coiitfh

vScarlet Fever Typhoid Fever Epidemic Cerebro-Spinal Meningitis

Small Pox Tuberculosis (Consumption)

(This report to be kept on file in creamery at least six months. )

APPENDIX E.

POSTER FOR DAIRY BARNS.
TWENTY DAIRY SUGGESTIONS WITH SPKCIAI, RKKKKKNCIV TO SANITATION.

fnited States Department of Agriculture, Bureau of Ajiimal Industry,

Dairy Division.

THK Cows.

1. Have the herd examined at least twice a year by a skilled veteri-

narian. Promptly remove animals suspected of being in bad health.
Never add an animal to the herd until certain it is free from dis-
ease, particularly tuberculosis.

2. Never allow a cow to be excited by fast driving, abuse, loud talking.

or unnecessary disturbance ; do not expose her to cold or storms
more than necessary.

3. Clean the entire body of the cow daily ; hair in the region of the

udder should be kept short by clipping.

4. Do not allow any strong-flavored food, like garlic, cabbage, or turnips,

to be eaten, except immediately after milking. Changes in feed
should be made gradually.

5. Provide fresh pure water in abundance, easy of access and not too cold.

THK STABILES.

6. Dairy cattle should be kept in a stable, preferably without cellar or

storage loft, and where no other animals are housed.

7. The stable should be light (4 square feet of glass per cow) and dry.

with at least 500 cubic feet of air space per animal. It should have-
air inlets and outlets, so arranged as to give good ventilation with-
out drafts of air on cows.

8. The floor should be tight and constructed preferably of cement ;

walls and ceilings should be tight, clean, free from cobwrebs, and
whitewashed twice a year. Have as few dust-catching ledges,
projections, and corners as possible.

9. Allow no dusty, musty, or dirty litter, or strong-smelling material

in the stable. Haul manure to field daily, or store under cover at
least 40 feet from stable. Use land plaster daily in gutter and on
floor.

APPENDIX E. 213

MII.K IIorsK.

10. Have- a light, clean, well-ventilated, and screened milk room, located

so as to be free from dust and odors.

11. Milk utensils should be made of metal, and all joints smoothly sold-

ered. Never allow utensils to become -rusty or rough inside. Use
them only for handling, storing, or delivering milk.

12. To clean dairy utensils, use only pure water. First rinse the uten-

sils in warm water. Then wash inside and out in hot water in
which a cleansing material has been dissolved, and rinse again.
Sterilize with boiling water or steam. Then keep inverted in pun-
air and sun, if possible, until wanted for use.

MILKING AXD HANDIJNG MILK.

13. Use no dry, dusty food just previous to milking.

14. The milker should wash his hands immediately before milking, and

milk with dry hands. He should wear a clean outer garment,
kept in a clean place when not in use. Tobacco should not be
used while milking.

15. Wipe the udder and surrounding parts with a clean damp cloth im-

mediately before milking.

16. In milking be quiet, quick, clean, and thorough. Commence milk-

ing at the same hour every morning and evening, and milk the
cows in the same order.

17. If any part of the milk is bloody, stringy, or unnatural in appear-

ance, or if by accident dirt gets into the milk pail, the whole should
be rejected.

18. Do not fill cans in the stable. Remove the milk of each cow at once

from the stable to milk room. Strain immediately through cotton
flannel or cotton. Cool to 50° F. as soon as strained. Store at
50° F. or lower.

19. Never mix warm milk with that which has been cooled, and do not

allow milk to freeze.

20. A person suffering from any disease, or who has been recently ex-

posed to a contagions disease, must remain away from the cows
and the milk.

INDEX.

Acid-fast organisms ....154

Acidity of milk ....182

Tests for ....166

Actinomycosis .... 86

Adulteration of milk ..187

Aeration of milk 15, 17, 25

Amer. Asso. Med. Milk Com-
missions 157, 158

Amer. Pub. Health Asso.. .141, 152
Ammonia refrigeration ....25

Analysis of milk .174

Anthrax... ....86

Apparatus, inspection of 105

Artificial digestion experiments 188
Aseptic milking 4, 8, 37

Ash of milk .... .176

B

Babcock test 179

Bacillus coli com munis 27, 55, 152

Bacillus diphtheria 52, 115

Bacillus lactimorbi ... 88

Bacillus lactis viscosus 31, 32, 33

Bacillus prodigiosus 2, 3

Bacillus proteus 55

Bacillus pseudo tuberculosis 154

Bacillus subtilis 29

Bacillus typhosus, carriers of, 45, 49
Effect heat upon .... ...115

Examination of milk and

water for...... 46, 152

Germicidal action upon . 36

In milk .45

Bacteria, effect of temperature

on 24,34

Growth of .24

In foremilk 5

In milk 1, 4, 23, 110, 165

In udder . .1

Killing of 115

Microscopic determination

of... 151

On udder 3, 4, 6

Spore-bearing ..116

Bactericide ... .115, 117

Bacteriological examination

of milk .-.141, 165

Numerical determinations

110, 141

Interpretation of results 150

Bacterium acidi lactici ...27, 28, 133

Bacterium diphtheric?, in milk... 52

Effect heat upon ... .115

Examination milk for 152

Bacterium lactis acidi. 26

Bacterium lactis aerogenes ... 27, 36
Bacteriu in tu bercu los is

(see tubercle bacilli)

Barns, improvement of.... 11

Sanitation of ...11

Barn-yards ... 5

Beet pulp .12

Benzoic acid ....166

Berkeley, Cal., tuberculin test

ordinance... 76, 195

Typhoid epidemic in 49

Bicarbonate of soda 192

Blended milk, Federal standard 183

Bloody milk .138

Borax" ....188, 190

Test for ...166

Boric acid ..188, 190

Boston, bacteria in milk of 24

Milk inspection in ....111

Bottle cap ... ....167

Sterilization of .16

Varieties of .168

Bottled milk . .16

Bottles 16, 17

Bottling machines .16

Bovine tuberculosis 59, 60, 164

Education concerning 85

In swine ..60

Measures against ... 67

Milk-borne 59

Physical examination for 68

. Prevalence of...... ....61

Views of Koch on 64

Brewers' grains 12

Budde's method of preserving

milk .; 26

Bur. Anim. Ind., score card of

95, 107

Buttermilk, Federal standard. .183

INDEX.

215

Carbohydrates ....176

Carbon dioxide refrigeration 25

Carbonate of soda 192

Care, of cow's coat 5

Milking- machines 9

Stables.. . .11

Udder 6

Utensils 13, 33

Casein in milk ....174

Cells, tests for (see leucocytes)

Certified milk 74, 156

Amount produced. ... .168

Certification label 167

Chemical examinations . 166

Cost 168

Fraudulent . ..168

Package ....167

Sanitary requirements of

dairymen.... 158

Standards for 169

Charbon (see anthrax)

Chemical examination of milk 166

Chemicals as preservatives .26

Chicago, pasteurization in 121

Tuberculin test ordinance

76, 200

City milk plants, score card 108

Coat of cow. . . 5

Collection of samples ...184

Coloring matter ...193

Colostrum : 87

Commercial pasteurization ....118
Commissions, milk 156

Experts of ...164

Field of 157

Source of authority 167

Composition of milk ... ... 174

Effect of feeding on 176

Condensed milk, Federal stand-
ard 183

Contamination of milk, 1, 2, 6, 45, 62
Significance .... ..23

Continuous-flow machines 120

Contracts, milk 76

Control of milk supply 93

Cooked taste of milk 115

Cooling milk 15, 25, 37, 121

Cowpox ... 87

Cream, alteration by heat 116

Thickening of ... 193

Cream, Federal standard.... 184

Cream, evaporated, Federal

standard .. ..184

Dairy Division, work of 102, 169
Dairymen and commissions 158

Dehorning 86

Delivery of milk ..16

Diarrhea, death rate 55

Epidemic 56

Digestion experiments 188

Diphtheria, milk-borne 51

Bacilli (see Bacterium}

In Oroville, Cal 53

Swab examinations 167

Diseases of man transmitted

by milk 41

Disinfection of stables 85

Dispensaries, milk .. .170

Distillers' grains ....12

District of Columbia, typhoid

in 42, 47, 123

Doane- Buckley test 129

Duluth, Minn., tuberculin test

ordinance 76, 206

E.

Education of dairymen. 85

Of public ...112

Epidemic diarrhea .... 56

Epidemic diseases and pasteur-
ization • 123

Epidemic diseases transmitted

by milk 41, 109

Evaporated milk, Federal

standard. 183

Examinations, bacteriological .165
Chemical 166

Experts of milk commissions .164

Fat, in certified milk '174

And specific gravity 180

Babcock test for 179

Determination of 179

Federal standards 169, 183

Feeding, effect on composition

of milk ....176

Feeds 12, 17

Fermentation, lactic acid 26

Filth ... 5, 33

Flavor of milk .... 17

Foot and mouth disease 88

Foremilk, bacteria in.. ....5

Formaldehyde . 166, 189

Leach's test for 191

France, dispensaries in 170

Fraudulent certified milk 168
Tuberculin test ... 80

216

INDEX .

Gastrointestinal infections 55

Germicidal activity 24, 34

Goat's milk, Federal standard 183
Croat's milk and Malta fever 87

H

Handling milk 15

Heat, effect on cream 116

Effect on milk 36, 115

Heated milk, tests for 166, 193

Heating (see pasteurization)
Hehner's test for formaldehyde 191
High-temperature pasteuriz-
ation 118

Hvdrogen peroxide 193

Ily^odcnna bovis 86

I

Identification of animals 75, 80

Indemnification for slaughtered

cows 82

Infant feeding arid pasteurized

milk.. 122

Infant mortality ... 55, 171

Infection, tuberculous .65

Infectious diseases, blank for

reporting 211

Inspected milk 74, 93, 112, 166

Inspection, of city milk plants

.'... 106, 111

Cows.... 105

Dairies 93, 123

Dairy apparatus ... 105

Water supplies ....106

Inspectors, qualifications of 93

Intern. Cong, on Tuberculosis ..66

Japan, tuberculosis in.
K

...66

ivoch, views on tuberculosis 64

Lactic acid fermentation 26

Leach's test for formaldehyde 191

Leucocytes in milk 36, 134

Standards for 127, 131, 137

Leucocyte tests 126

Doane-Buckley 129

Savage's ... 131

Slack's 128

Stewart's ...127

Stokes'.... 126

Trommsdorff's 131

Live stock industry . 59

Low-temperature pasteuriz-
ation 117

M

Malta fever 87

Mammitis in cows 69, 86, 126, 136

Mangers ... 11

Manure, disposal of 11

Tubercle bacilli in . 63

Market milk, bacteria in .. 24

Tubercle bacilli in 63

Medical inspection, certified

milk 167

Micrococci in milk 3, 134

Micrococcus I act is varians 3

Micrococcus melitensis .87

Micrococcus pyogen/es aurcus 4

Microscopic estimate of bacteria 151
Microscopic tests of milk ....126
Milk, adulteration of.... 187

Milk-borne diphtheria 51

Milk-borne epidemics . . .41, 109

Milk-borne scarlet fever 54

Milk commissions 156

Experts of.. 164

Milk, composition of 23, 174

Milk, contamination of 1,2, 6, 45,62

Milk dispensaries 170

Milk, Federal standard .... ..183

•Milk flavors 17

Milk, handling of 15

Milk pail, shape of .. .7

Milk room 12, 16

Milk sediments .... 17

Milk-sickness ....88

Milk, watering of ...191

Milker 8

Milking machines 8

Mineral matter 176

Municipal sanitary control of

milk" 70, 93

Of pasteurization 123

Of tuberculin test 75

Mvcotic stomatitis 88

N

New York, blank for infectious

diseases 121

Pasteurization in 121

N. Y. S. Coll. of Agri., score

card ..97

Numerical determinations (see

bacteriological examination)

INDEX.

217

O

Ordinances, tuberculin test 72, S5
Berkeley, Cal. 76, 195

Chicago, 111. ...76, 200

Duluth, Minn. 76, 206

Washington, I). C. ...73

Palo Alto, typhoid epidemic in 46

Parturition disturbances 87

Pasteurization of milk 71, 74, 114

Commercial .118

Continuous-flow .. .120

Efficiency of... 119

High-temperature 118

In Chicago . 121

In New York ....121

In Washington 73

Low-temperature . ...117
Machines for . ..117
Pasteurized milk, Federal stand-
ard 183

For infant feeding ... 122

Phagocytosis 36

Physical examination for tuber-
culosis .... ....68

Preservatives.. .26, 187

Tests for... 166, 190

Protein ..174

Pus cells in milk 135

Putrefaction . 29

Qualitative determinations
R

154

Refrigeration (see cooling)

Richmond, Va., score card 103

Rochester, N. Y., milk dispen- '

saries ..170

Rooms, special milking 12

Ropy milk 30

St. I^ouis, certified milk in 167
Salicylic acid 166, 188

Samples, collection of ....184

Sampling milk 177

Sanitary control of barns ...11

Of "milk 93, 158

Savage's test ... 131

Scalding of utensils 13

Scarlet fever, milk-borne 54

Score card . 94, 97, lo?

Scores of certified dairies 169

Scores of dairies in Richmond,

Va. 103

In Washington, I). C. 104

Sediments in milk 17

Skim milk, Federal standard 183

Skim milk, condensed, Federal

standard .183

Skimmed milk, indication of ISO
Skimming, tests for 192

Slack's test 128

Slaughter of tubercular cows 84
Solids. of milk 175

vSolids not fat ISO

Sour milk as food 28

Souring of milk 26, 29

Specific gravity . 177,180

Spore-bearing bacteria 116

S tables, dairy ..10

Sanitation of ... 72

Stanchions 11

Standards, Federal. ..169, 183

Standards, state .184

Staphylococctts pyogencs aureus
( see micrococcus pyo-
gciics nit re us]

State standards ...184

Sterilization of milk 114

Of utensils .13

Sterilized milk, Federal stand-
ard 183
Stewart's test... 127
Stokes' test 126
Strainers ... 15
Strainer pails 7
Straining, effect of 8, 17
Streptococcus in gastro-intes-

tinal infections 55

In mammitis 4, 126

In milk 4, 133

Determination of .154

Streptococcus I adieus 26, 27, 133
Streptococcus pyogrncs 4

Strippings .... 2

Sugar-beet pulp 12

Suppuration 86

Swine, tuberculosis in • 60

Taints in milk 15, 17

Temperature, effect on bacterial

' growth 24, 34

Interpretation of 79

Temperature standard of milk 109
Temperature in tuberculin test

... 77, 79

218

INDEX.

Tests, -Babcock's 179

Doane-Buckley '.129

Hehner's.... 191

Leach's ... 191

Microscopic 125

Municipal ., 75

Savage's 131

Slack's..... 128

Stewart's .... 127

Stokes' .126

Trommsdorff's 131

Tuberculin (see tuberculin

test)
Thickening agents .... ....193

Time in pasteurization ..117

Toxic milk ,30

Toxins 55

Transportation of milk 25

Trommsdorff' s test.... 131

Tubercle bacillus, bovine in man 64

Effect of heat upon .115

In manure 63

In milk 62, 63, 153

Types of 63

Tubercular animals 84

Tuberculin .71, 77, 79

Tuberculin test. .71, 72, 75, 165

Application of 77

Limitations of 79

Ordinances (see ordinances)

Tuberculosis, and milk supply 67

Bovine ... 59

Channels of infection 65

Disinfection for 85

In Japan 66

In swine 60

International Congress on
Measures against
Milk-borne...:

Of udder

Prevalence

Stable sanitation
Tests for

Typhoid fever

And pasteurization

Bacillus

Epidemics
Milk -borne....

66

67

59, 64

69
61

72
71
42

...123
45, 152
.46, 49
42, 123

U

Udder, bacteria in 1,7

Cleansing of 6

Contamination from exterior 6

Diseases of 86, 126

Tuberculosis of 62, 69

U. S. Dept. Agri., poster 212

Utensils, cleansing of 13

Construction of 15

Inspection of . 105

Veterinary inspection 164

Vital qualities of milk 116

W

Washington, control of tuber-
culosis 73
Milk supply 24, 73
Pasteurization .123
Score card ....104
Water supply of dairies 106
Watered milk, indication of 191

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