DIVISION OF BOTANY 479 



SESSIONAL PAPER No. 16 



While most kinds of these organisms are not actually disease-causing, yet they 

 may very quickly spoil for human consumption milk and other food that would remain 

 wholesome otherwise. Where, however, the bacterial purity of milk becomes of great 

 moment, is at times when certain germ epidemics prevail, such as typhoid, cholera, 

 infantile diarrhoea, and also the ever-present scourge of mankind, tuberculosis. All 

 of these serious diseases have been communicated by means of infected milk, and for 

 these reasons the freedom of milk from disease-causing organisms especially, is one of 

 the most vital necessities of the milk supply of cities. 



The work was begun in July, 1912, and preliminary investigations were carried 

 out to discover the sources of bacteria in the milk. 



Thus the bacterial content of the stable air were examined, when the floor was 

 dry or sprinkled with water, also several kinds of bedding were tested; the cows were 

 also bacterially inspected before and after cleaning in order to keep trace of bacteria 

 falling from the animals into the pail during milking. 



The men engaged in milking were cautioned to observe particular cleanliness. 

 The hands of the milkers were examined occasionally for bacterial contamination; 

 also the milk pails, cans, bottles were carefully examined before and after special 

 cleaning operations. In this manner some very interesting data came to light, and 

 after eliminating the sources of contamination as much as possible, the bacterial 

 contents of the milk were then regularly examined. From time to time check examina- 

 tions were made in order to discover any infringements of the rules of sanitation. 



About a week was required to get the results to coincide, which they very accur- 

 ately did after that time. 



At first, hand milking was employed alone. From July 25th, a milking machine 

 was put into operation and comparative tests were conducted to find out by which 

 method the purest milk could be obtained. Throughout our tests, the hand milk was 

 cleaner than the machine milk. The reason for this was that the rubber tubing of 

 the milking machine soon got into a condition where no matter how carefully clean- 

 ing was practised, it could not be made quite sweet and pure, but when the old tubing, 

 etc., was changed for new, the bacterial purity immediately improved. 



It was also found that the milk cans sent in by dairies to receive milk at the farms 

 were far from being bacteriologically pure. 



A new cotton wadding filter was tried, the milk being tested with and without 

 its use. At first, the contents of the unfiltered milk was lower than that of the filtered 

 milk. After cleaning the filters properly, the unfiltered milk was less pure. Very 

 little gain resulted from the use of these filters as far as bacteria were concerned. 

 Dirt, etc., was, however, very satisfactorily removed. 



The effect of a milk cooler on the bacteria contents was also tested. The imme- 

 diate cooling of the milk was found of great service in preventing the increase of 

 bacteria that occurred in uncooled milk. 



Comparative tests of several types of milk pails were also made. Each type of 

 pail was in use for the same period, and the results were in favour of the hooded pails. 



It will be of interest at the present time, where several types of milking machines 

 are in use at various places, to give in detail some of our comparative tests of milk 

 obtained by machine versus hand milking. 



