DAIRY FARMING DAIKYTNG, 911 



milk of one cow, which was obhiined by the method outlined and by the ordinary 

 method on alternate days. I^aniples were kept at 70° antl at 50° F. 



The extra precautions mentioned reduced the l)acterial content of the fresh inilk 

 in two series of t'xpeiinients from averages (jf o,<S,S<S and o,ll() bacteria per cubic cen- 

 timeter to 2()7 and 242, l)ut apparently increased the percentage of lactic-acid bac- 

 teria. In no instani'e was the typical Bocteriain hidis acidi found. 



In the samples kept at 70° the bacteria multiplied more rapidly in ordinary milk 

 than in the aseptic: milk. The aseptic milk showed in practicall}' every instance a 

 smaller nundjer of l)acteria at the end of 12, 24, and ;>() hours tlian milk drawn in the 

 ordinary way. The development of acid was correspondingly nuicli slower in the 

 aseptic samples. Ordinary milk curdled, on an average, in 79 hours and aseptic Jiiilk 

 in llo hours. 



In the sami)les kept at 50° the differences were even greater than in the samples 

 kept at 70°. The average increase of bacteria at this temperature in .'!() hours was 

 10-fold in the aseptic milk and oO-fold in the ordinary milk. The time of curdling 

 was, respectively, 226 and 400 hours. It is considered that the most striking results 

 of the expei'iments were the effect of a temperature of 50° in checking bacterial 

 growth and in improving the keeping quality of the milk. The lower temperature 

 checked the development of lactic-acid bacteria and favored the devt'lopment of 

 miscellaneous species. 



Qualitative analysis of bacteria in market milk, H. W. Conn and W. M. Esten 

 ( Coiiiu'cticut Storm Sta. lipf. 190-J, pp. 63-91) . — In continuation of investigations pre- 

 viousl)' reported (E. B. R., 13, pp. 688, 987), bacteriological examinations were made 

 of the market milk of Middletown, Conn. The milk was obtained from about 20 

 milkmen, and was supj)Osed to be from 2 to 12 hours old. The methods of examina- 

 tion emi)loyed were the same as those previously descrilted. The l)acteria ordinarily 

 found in normal milk are divided into 12 groups, each of which is descrilied. Data 

 for selectetl experiments are reported in this article, and a nundoer of conclusions are 

 draw n. 



Tlie num))er of bacteria varied from 8,000 to 2,900,000 per cubic centimeter. In a 

 general way the percentage of lactic-acid bacteria increased with the total nund)er. 

 An increase in the total number of bacteria was associated with a decrease in the 

 nund)er of varieties. On the other hand, a small nund^er of bacteria was associated, 

 as a rule, with a large number (jf varieties. The liijuefying bacteria in general varied 

 inversely as the total nund)er of bacteria, and also inversely as the percentage of 

 lactic-acid Ijai-teria. The liiiuefying bacteria also varied with the season, the mmdjer 

 being greater during May and June than during the several months i)receding. The 

 mnuber of varieties of bacteria varied greatly in the different samples, in some cases 

 being only 4 or 5, while in others no less than 17 species were recognized. 



Comparative tests were made of several modifications of the methoils of study pre- 

 \iously described and used in the above investigations. It has been found preferable 

 to sterilize tlie litmus solution separately and add it to the gelatin at the time of using, 

 thussecuringagreater uniformity in the color of themedium. Three culture media — 

 whey gelatin, ])ei)tone gelatin, and milk custard — were tried alone and in different 

 mixtures. Part of the data for these tests are included in the rejwrt. The most sat- 

 isfactory medium for all purj)Oses, including both (|uantitative and (lualitative analy- 

 sis, has been found to be a mixture of the connnon beef ])eptone gelatin and the whey 

 gelatin, litnuis being added in a manner to secure uniformity ul color in the differ- 

 ent plates. 



Bacteria in freshly drawn milk, H. W. Conn {ConnecficiU Storr.s Stn. lipt. I'JOS, 

 pp. 92-'js). — This is a comparison of the results obtained l)y Harrison and Cununing 

 ( K. S. R., 14, p. 907) with those obtained in Connecticut. In the work at Middle- 

 town anil 8torrs, Conn., the number of bacteria found in the fore milk has l)een 

 much lower, the average of 70 experiments being 6,900 bacteria per cubic centimeter, 



