422 



by means of the separator or by sottiiij;, 1>v far the larger number of 

 the bacteria contained in tlie whole milk i)ass into the cream, the 

 remainder appearing in the skim milk, or a very small amount in the dirt 

 of the separator. The anthrax spores and bacilli, bacteria of t\-i>hoid 

 fever, and cholera spirilli follow the same course as the common milk 

 bacteria, that is are largely separated with the cream, but the tuber- 

 culosis bacilli are said to form an exception to the rule, being mostly 

 separated by the centrifuge, but sinking to the bottom of the vessel on 

 standing. More or less of the latter, however, remain in the separator 

 milk and the cream. The tests were made with a centrifuge run at the 

 rate of ti'oin L'.(>00 to 4.00() levolutions i»er minute. 



Bacteriological studies of butter, F. Lafar {Arch./. Hygiene, 13, 

 2)p. S'J). — The author made numerous determinations of the number 

 of bacteria in samjjles of fresli butter direct from a creamery, and found 

 that in the, majority of the samples the number of live germs per gram 

 of butter ranged from ten to twenty millions. About twenty times as 

 many germs w<Me Ibnml in samples taken from the surface as in those 

 taken from the inner jMirtions of the material. Of the organisms 

 noticed, two, liaetrrium butyri coUoidcum and Bacillus hutyri Huorcscens, 

 occurred in every sample of natural butter examined; sprouting fungi, 

 which were not further studied, and Jiacilhm acidi lactiei (Hu«*i)pe) 

 occurred ofti'u; and JUictcrium (cnxjeneif Uictis (Escherich) was noticed 

 in one case. Xo molds were notic«'d in any case. A lengthy d«s< rip- 

 tion is given of the two typical forms of bacteria isolated. 



SampU^s of fresh natural butter were kept in the cold <lui ing winter, 

 and determinations made from time to time of the number of organisms 

 capable of germinating, with a view to observing the effect of contin- 

 ued cold on the vitality of these organisms. A sample kept for 14 

 days at a temperature ranging from 1° ab(»ve to 15^ below zero C, 

 showed a destruction of only about one third of the organisms. The 

 sample kept on ice for .'57 «lays showed a marked decrease in the number 

 of germs during the lirst week, but after that ke]>t without further 

 loss. Samples kept at room temi)erature (lli- to lo^ C.) increased rap- 

 idly in the number of organisms for the first few days, but after that, 

 with theincreasing rancidity of the butter, the organisms rapidly <limin- 

 ished in nuinbi-r. It was notice<l that lUwiUus butyri fhiortscens. which 

 occurred in large mimbers in the fresh samjiles, decreased in number 

 with the increasing rancidity. It was noticed with samples kept in the 

 ])rceding oven at a teiniierature of li~t^ ('. that after 4 days the num 

 ber of germs had decreased more than half. This decrease Ment on 

 regularly until at the end of .34 days the butter contained only 5 per 

 centof th«> original number of germs. Protracte<l cold was there ff>re less 

 successful in reducing the number of germs than the temperature of the 

 breeding oven. Tests of the effect of adding salt to l)utter kept at a low 

 temperature indicated that while the addition of salt considerably 



