80 EXPKIMMKN r STAIION KECORD. 



The effect of autolysis on the precipitogenic characteristics of milk, TI. ni; 

 Waki.k (liUnUcin. Zlschr., 7 {l!)()S), .Vo. '/-(;. />//. '/0/-',0«).— Aeronliiit; to llif 

 oxiifi-iiiHMils r('|p(irtt'(l the iiiitolysis of milk im-rc-ises its i)ivcipito,ir«'iiic action. 



The influence of the oxygen of the air upon fermentation by typical lactic- 

 acid bacteria, (J. Koksti.kr (Centhl. Bakt. [etc.], 2. AM., 19 {1901)', Nos. 1-3, 

 pp. -'iO-Ji9; ',-(■>, pp. 128-1^8; 7-9, pp. 236-255; 13-15, pp. 39'i-.',19, fifju. 18; ah.s. 

 ill Hyg. Zenihl., 3 (1908), No. 18, p. 558).— From the results of the investiga- 

 tions reported the author concludes that oxy{:(>n had a dil1"erent effec-t upon 

 different lactic organisms. 



lid etc it It III f/iiiithrii was l)ut slightly sensitive to free oxygen, whereas Bacil- 

 liifi casri e was very sensitive. The effect on this organism varied according to 

 the quantity of oxygen supplied. With an abundant supply fermentation was 

 largely prevented; there was, however, a rich vegetative development of the 

 organisms, but they were not healthy. A scanty oxygen supply was practically 

 vfitliout effect. With intermediate aeration there was a maximum acid produc- 

 tion and normal cell development. The results indicate that oxygen in large 

 quantities had a toxic effect and in moderate quantities a stimulating effect. 

 This phenomenon can not be explained by Beijerinclv's microserophilus hypothe- 

 sis, because the same degree of acidity was produced under positive anaerobic 

 conditions as with the free access of air. With controlled aeration the degree of 

 acidity produced depended upon the temperature and the content cf the nutrient 

 medium in assimilable nitrogenous compounds. A continuous oxygen supply 

 was not necessary for fermentation, an occasii)nal exposure of the medium to 

 air with shaking being sufficient. 



Butter from sweet cream, A. T. Charron (Rpt. Ddiri/iiirii's Assoc. Prov. 

 Quebec, 25 {1906), pp. 238-2-^6). — Results of experiments in making butter 

 from sweet cream are discussed. It is claimed that the process is just as 

 advantageous as that with ripened cream, and that tlie butter made from sweet 

 cream is equally good when fresli and keei)s good longer tlian butter from cream 

 si)ontaneously fermented. 



Influence of metals on the action of rennet, G. A. Olson ( Wisconsin t^ta. 

 Rpt. 1901, pp. 13'i-159, figs. 7). — The author summarizes information regarding 

 a number of conditions which influence the action of rennet on milk and reports 

 the results of investigations on the effect of different metals. Milk was kept 

 in contact with copper, zinc, lead, nickel, aluminum, tin, iron, and platinum, and 

 different kinds of glass for different periods of time and afterwards the time 

 required for the coagulation of such milk with a standard solution of rennet 

 under uniform conditions was observed to learn what influence, if any, these 

 substances had on the action of the rennet and whether this was characteristic 

 for each substance. 



" The data given show beyond a doubt that metals in some way delay the 

 coagulation of milk with rennet. Different milks respond differently ; the most 

 striking retardations were observed with pure nickel. The retardations that 

 are most doubtful are those observed with platinum and tin. It is hardly con- 

 ceivable that salts of platinum or tin should be formed bj' the acid of the milk. 

 When tin is treated with lactic acid a slight visible corrosion takes place, while 

 on the other hand platinum remains uncorroded." 



The direct cause for retardation of rennet by metal was not ascertained. 

 Practical application of the information obtained in these studies is made in 

 avoiding the use of rusty cans or poorly tinned utensils in the creamery or 

 cheese factory. " The quality of the milk will to a large extent depend upon 

 the condition of utensils in which the milk is kept or hauled to the factory. 

 The degree of influence of iron on milk will depend largely upon the temper- 

 atui-e, the length of time kept, and the amount of surface." 



