(2) There is a great increase in contamination in the milk at each stage before it reaches the customer.
This provides for the reduction as far as possible of contamination during the milking process itself.
The unavoidable contamination with muddy particles of vat-waste is removed by allowing the vatliquor to rest for some hours in a separate tank and settling out the mud.
If the contamination exceed a certain limit, the scrapings remain quite dead.
(2) The Institute is of opinion that in the hands of more or less unskilled workers it is easier to ensure freedom from contamination by Haffkine's ` standard method ' of manufacturing plague vaccine than with the ` water agar process ' as employed by him.