994 



Ropy Milk. 



[march, 



certain kinds of ropy milk being much prized in some coun- 

 tries as an article of diet, but its mechanical condition and 

 appearance are so abnormal that it must be quite an acquired 

 taste. The writer has given ropy whey (made from Bacillus 

 lebenis) to pigs, and found they apparently preferred it to 

 ordinary whey. 



History of Investigations. — In 1847 Girardin investigated ropy 

 milk from the chemical point of view, and tried to find the cause 

 in the defective composition of the fodder. Lister (2) was, however, 

 the first to infect milk artificially with the disease. 



Schmidt-Mulheim was the first to investigate ropy milk from a 

 bacteriological point of view; he published his results in 1883 (3). 

 He found it to be caused by a round organism (Micrococcus viscosus), 

 about 2MT00 °f an inch in diameter, which was capable of movement, 

 and occurred frequently in chains. Ropiness is caused by this 

 organism in from 18 to 24 hours. 



Since the discovery of this organism many others have been isolated 

 and named (see list in appendix A). They vary very much in size 

 and shape, some being large round forms, others smaller. Large 

 and small rod-shaped organisms may also be the cause of this milk 

 fault. 



Distribution and Source of Ropy Milk Organisms. 



These organisms are described in the following paragraphs from 

 the practical point of view, with special reference to their source 

 and distribution. 



Group I. 

 Bacillus lactis viscosus, Adametz. 

 Probably the most important organism from the dairy farmer's 

 point of view is one discovered by Adametz, which seems to be very 

 widely distributed, and has been very fully investigated by him in 

 Vienna, by Ward (4) in America, by Barthel (5) in Stockholm, and 

 was also investigated in 1911 by Mr. Wilfrid Sadler and the writer, who 

 found it to be the cause of a very persistent outbreak of the trouble 

 in Notts. 



Adametz first found it present in the Peter's Brook water near 

 Vienna, and also in the effluent from the Liesinger Brewery. In the 

 former case 100 to 200, and in the latter 1,000 of these organisms 

 were present per cubic centimetre.* 



Ward states that the minimum temperature for the growth of this 

 organism is 46 0 F. (8° C), and the maximum temperature is 104 0 F. 

 (40 0 C.). He has come across a case of ropiness caused by this 

 bacillus in milk kept at 45 0 to 50 0 F., i.e., at the temperature of 

 cooled milk. Freezing for 24 hours does not destroy the vitality 

 of the organism. 



Ropy Cream. — When milk is " set " for 30 to 40 hours after 

 inoculating with Bacillus lactis viscosus, the cream only goes ropy. 



* These determinations were made by inoculating sterile tubes of milk with 

 attenuations of the water. 



