92 BACTERIOLOGY 



Bacillary Group, but other organisms are also used. A suit- 

 able temperature, 20 to 30 Centigrade, and cleanliness con- 

 forming more or less to a bacteriological standard, together 

 with a prelinrnary pasteurisation before adding the starters, 

 are essential to true scientific butter-making, but as yet even 

 a rudimentary knowledge of these important facts is not within 

 the range of an ordinary dairy-farmer's education ! The scien- 

 tific dairyman should also know of the existence of starters of 

 a hurtful type, which lead to the production of butter having 

 a rancid, bitter, oily, or otherwise objectionable taste. At 

 present he explains to the unsuspecting public that the 

 " turnipy taste " of his butter is inevitable, as the cows are 

 being fed upon turnips, instead of informing them that the 

 taste is really due to organisms, especially of the B. coli type, 

 which are inoculated into the milk and cream from cow-dung 

 and other even more objectionable sources. 



Cheese-making also owes its success or failure to the presence 

 of suitable organisms various Bacteria, Moulds and Yeasts. 

 The casein or coagulable protein of milk is usually first preci- 

 pitated by the action of rennet. The ripening of this casein 

 is then carried out, either by the haphazard, or by the scienti- 

 fic inoculation with the special group of organisms character- 

 istic of the type of cheese to be made. " Diseases " of cheese, 

 like those of butter, are caused by the presence of harmful 

 organisms which may make it bitter or rancid or even abso- 

 lutely putrid, or it may be broken up or rendered spongy by 

 gas-producing bacteria. 



Koumiss, made from mare's milk, Kefir, made from cow's 

 milk, and other forms of Fermented Milk are produced by the 

 action of certain bacteria which by their action render the 

 milk-curd more digestible and therefore sometimes useful as 

 a diet for invalids. 



The Retting of Flax and Hemp. In order to separate and 

 obtain the fibres of flax and hemp, from which linen and ropes, 

 string, etc., are respectively made, the stems of these plants are 

 rotted or retted in water or upon damp ground in order to 

 soften them and allow of the isolation of the fibres. This rot- 

 ting is really a modified process of putrefaction, and is brought 

 about by the action of certain specific bacteria. Cocoanut fibre 

 is similarly obtained. 



Tanning. The characteristic odour of a tannery is a some- 

 what unpleasant reminder that bacteria are closely concerned 

 with many of the processes carried on within its precincts. 

 After Drying and Salting, the hides are cleared of hair either 



