776 EXPERIMENT STATION EECOED. 



have been the chief means for accurate knowledge of sanitary condition and 

 the omissions in practice responsible for contaminated milk. 



Marked results were noted as the result of the elimination of dust from the 

 barn. It is stated that dust in the barn and the failure to sterilize utensils are 

 two of the chief reasons for high bacterial counts. These conclusions are rather 

 in contrast to those reached by the New York State Station (E. S. R., 34, 

 p. 183). 



Hygienic milk, J. Pbitzkee {Schweiz. Apotli. Ztg., 53 {1915), Xos. 42, pp. 

 583-586; 43, pp. 593-597; 44, pp. 609-612; 45, pp. 624-62S).—\ summary and 

 digest of data, including the findings of bacteriological examinations of milk 

 prepared under various conditions of cleanliness. It is maintained that raw 

 milk obtained and handled with proper precautions is the best substitute for 

 mother's milk. Pasteurization and sterilization reduce the number of bacteria, 

 but boiling alters the chemical composition of the milk. Sterilized milk is con- 

 sidered responsible for rachitis and scurvy in infants. 



Slimy and ropy milk, R. E. BrciiAXAN and B. W. Hammer {loxca f^ta. Re- 

 search Bui. 22 (1915), pp. 207-295, figs. 10). — A study of slimy and ropy milk 

 sent in for examination to the dairy bacteriological laboratories has shown the 

 following : 



" Cultures of organisms secured from slimy starters, apparently typical 

 Streptococcus lacticus forms, sometimes showed marked capacity to produce, 

 ropiness when inoculated into sterile milk. This slime-producing power is 

 evidently a variable characteristic, appearing and disappearing without ap- 

 parent cause. Associative action of organisms in some cases is responsible for 

 ropiness. Two organisms, neither of which alone can cause ropiness, may, 

 when grown together, caiise the medium to become slimy. Bacterium (lactis) 

 viscosum Is one common ca\ise of slimy milk. Certain peptonizing bacteria, 

 as B. pcptogencfi, produce a very slimy residuum after digestion of the casein. 

 B. hulgaricum. and certain related high acid organisms frequently produce 

 marked viscosity in milk. 



" Sllminess in milk is apparently due to different causes with different organ- 

 Isms: Gum and g\imlike capsular materials partially soluble, or at least swelling 

 In water, are frequently the same. In many cases there seems to be a direct 

 relationship between chain formation of streptococcus and the development of 

 ropiness, likewise between the numbers of bacteria and ropiness. Associ.-itive 

 action between two distinct organisms resulting in great increases in number 

 of each is not uncommon as a cause of ropiness. Methods of control and pre- 

 vention of slimy milk are discussed." 



Keys to the organisms tliat have been described as responsible for slimy 

 production in milk are presented. An attempt has been made to clear up 

 synonymy. Descriptions of 33 species of bacteria tliat have been found asso- 

 ciated with milk are given, and the literature reviewed. A bibliography is 

 appended. 



Effect of salt on butter flora, W. Gixtner and .1. D. Bakeb {MicJiigan Sta. 

 Rpt. 1915, p. 209). — It has been found that salt to a concentration of 12 per 

 cent does not in all cases retard growth, an<l that the growth of some organisms 

 is not prohibited by 20 per cent of salt. Streptococci are sensitive to salt, wliile 

 micrococci and staphylococci can tolerate a high percentage. IVIost of the yeasts 

 and torulre of butter are not easily affected by salt, yet they can not withstand 

 as much salt as some of the cocci. Salt (8 per cent) retards the physiological 

 processes of most organisms. Micro-organisms which liquefy casein and gelatin 

 are more easily affected by salt than nonliquefiers. Some organisms by con- 

 tinued cultivation on salt agar increase their maximum tolerance for salt. 



