1912.] 



Ropy Milk. 



995 



The skim milk is never slimy. Lactic acid bacteria are formed in it 

 which prevent the development of this ropy milk organism. 



Ropy cream can be used for butter-making, and only when very 

 ropy has the butter a rather soft and smeary appearance. Butter 

 made from cream even if only slightly ropy decomposes very quickly. 

 In an experiment carried out by Adametz the milk of certain cows 

 was inoculated with this organism, and the cream afterwards made 

 into butter; this butter went rancid in 8 to 10 days, while butter 

 used as control was quite good after three weeks. "When the butter 

 from ropy milk was cut through it showed little holes and looked 

 like soft cheese." 



It is thus seen that B. lactis viscosus^ unlike the acid-producing 

 ropy milk organisms of Group IL, does not tend to increase keeping 

 qualities, but, on the contrary, probably favours decomposition. 



Ward found the B. lactis viscosus in a wooden tank of ice water 

 in which the "40 quart cans" of milk stood every night. The particles 

 of damp sawdust on the floor, which were introduced along with the 

 ice, also brought about a slight viscosity when added to sterile milk. 

 Ward states that dust infected the milk in the creamery. 



One dealer discontinued the cooling of the milk, thus giving the 

 ordinary lactic organisms a cn'ance to crowd out the other less common 

 organisms. 



C. H. Eckles, of Iowa, who isolated B. lactis viscosus from 

 twelve samples of ropy milk and from the air of a stable and a 

 creamery, states: — "The occurrence of ropy milk shows that one con- 

 dition of good handling has been observed — that of cooling." 



Chr. Barthel investigated two cases uf ropy milk in Stockholm, 

 and he attributed the cause to B. lactis viscosus. In one case the 

 organism was thought to have been in some hay which was used 

 for littering, but this was not proved. 



Micrococcus Freudenreichii, Guillebeau. 

 Freudenreich states that the chief cause of ropy milk in Switzerland 

 is a large, round coccus, with a diameter of j^ioo °f an inch. It is 

 non-motile, and, unlike B. lactis viscosus, liquefies gelatine. In 

 sterilised milk it thrives best at 68° F. This organism grows with 

 such speed and vigour that even unsterilised milk when inoculated 

 with it exhibits a noticeable change in five hours. 



Bacterium Hessii, Guillebeau. 



Guillebeau isolated an organism from the milk of a cow from a 

 mountain pasture in Switzerland. Although it makes cream slightly 

 stringy it is not probable that it is of practical importance as the 

 sliminess disappears as soon as a little acid is produced. 



Straw Coccus. 



A coccus which makes milk ropy was discovered by Hohl in samples 

 taken from the interior of bundles of pressed straw which had been sent 

 from the French provinces to Switzerland. 



It is interesting as an instance of a possible source of the trouble, 

 but has not at present been proved to be the cause of an outbreak 

 of ropy milk. 



