204 STATE BOARD OF AGRICULTURE. 



of appearances in the precipitated casein. There would be all shades, 

 from the truly loppered milk to the finely granular particles of casein 

 often produced by the action of bacteria. While we are able to affirm that 

 these conditions exist and are able to see them and note the differences, 

 yet we are unable by the use of language, to describe these differences. 



A rennet action consists in the precipitation of casein and may occur 

 under acid or alkaline conditions of milk. In the formation of lactic acid 

 the casein is precipitated by the direct action of the acid upon the casein; 

 but when we have a neutral or alkaline solution, the action is different, 

 it is the result of a ferment produced by bacteria. This ferment is 

 capable of separation; it, when isolated, may be introduced into milk and 

 produce the precipitation of the casein. 



In a large number of species of bacteria obtained from Pasteurized 

 milk, it is markedly noticeable that most of them will precipitate the 

 casein of milk without the formation of anv acid. 



BITTER MILK. 



It is not an unusual occurrence upon tasting a bowl of milk to find that 

 it is bitter. This bitterness is due to bacteria which gain access to the 

 milk and then give rise to products of a bitter taste. Hueppe was of the 

 opinion that this bitterness was due to the formation of peptones by the 

 peptonizing bacteria and we are not at all certain that this action is not 

 in certain cases accompanied by bitterness, although in many cases it 

 seems the result of special products. 



Dairies and factories have been visited by these bitter milk bacteria 

 with great loss. Weigmann has also demonstrated their presence in 

 cheese. Wherever they are found in milk or its products the total 

 destruction of the material usually follows. 



ROPY OR SLIMY MILK. 



The subject of ropy milk has been discussed in Bulletin 140, in which 

 was described a bacillus that was found to produce ropy cream. It will 

 not be out of place, however, to mention in this connection a few of the 

 most important features of ropy milk and cream. The number of bac- 

 teria producing this condition of milk and cream is exceedingly large 

 and if more attention were given to the morphological and cultural 

 study of these bacteria, this number could probably be reduced con- 

 siderably, because it would probably be found that several of these now 

 distinct species would be proved identical. The one cited in Bulletin 

 140 has many characteristics common with several of the species 

 concerned in the production of ropy milk; yet owing to the scarcity of 

 detailed data, it was impossible to identify it at the time of writing 

 the bulletin. We will not stop, however, to consider the various bacteria 

 as species associated with this condition of milk and cream, but will 

 only state that they vary greatly in their methods. 



One species will produce ropy milk through the adherence of one 

 bacterium to ano+her by means of an adhesive cell wall, and this ropiness 

 will not only manifest itself in milk but also in other media in which 



