2U STATE BOARD OF AGRICULTURE 



ROPINESS IN CREAM OR MILK. 



];y c e Marshall. 



Bulletin No. 140. — Veterinary Department. 



When milk or cream may be drawn out in threads or strings, or when 

 either presents a slimy appearance of a stringy formation, the term, ropy, 

 stringy, or elimy has been given to this condition, designating thereby, a 

 diseased state which prevails to some extent among dairies, factories, and 

 wherever milk is handled. It is, by no means, a new disease; on the con- 

 trary, milk analysts have struggled with it for decades, but without posi- 

 tive results. It was not until the biological explanation of many chemical 

 changes was instituted by Pasteur, in his experimental work upon milk, 

 wine, and beer fermentations, and suggested by others previous to him, 

 but not worked out, that such perplexing questions as milk ropiness as well 

 •as other milk fermentations could be regarded in a reasonable light. Pas- 

 teur was able to say that a certain yeast plant could produce ropiness of 

 milk, yet he failed to comply with the later requisitions of bacteriology in 

 establishing beyond a doubt the exact relation existing between that yeast 

 plant and the milk. Lister was the first to separate a distinct species 

 which would produce ropiness in milk. Since Lister's time many species 

 have been isolated and identified as connected with this peculiar fermen- 

 tation. Each kind has its particular action. While all may be classed as 

 giving rise to ropy milk or cream, do two of them will produce this con- 

 dition in juet the same way, nor will the milk give exactly the same 

 appearance. Sometimes it is due to the bacteria adhering together in a 

 ropy mass, caused by the secretion of a gum-like substance by the indi- 

 vidual bacteria. In this case a string of micro-organisms may be pulled 

 out with the milk or cream, thus rendering their functions only in an 

 indirect way. Such bacteria are not so likely to decompose the milk by 

 the destruction of any element composiug it. They, of course, feed upon 

 some of the constituents of the milk, but a change is not likely to occur in 

 the component parts. On the other hand, there are those bacteria acting 

 directly upon the milk sugar in the production of slime or ropiness, con- 

 suming a part of that substance. Then there are those whose action is 

 more complicated, involving the other constituents of the milk. 



Very frequently in normal milk, that is, milk kept under the usual con- 

 ditions, bacteria are found which, unaccompanied by other bacteria, will 

 manufacture ropy milk. The other bacteria ordinarily gain the ascendency 

 and perform their functions before the bacteria producing ropiness can 

 manifest themselves. Should the latter gain the ascendency, ropiness 

 would occur and the cases of ropy milk would be multiplied greatly, 



