( 34) 



and 18° C. in malt extract and transferring to boiled milk or whey 

 at a somewhat higher temperature. The acidity obtained remains low 

 and amounts to 3 to 5 c.c. of normal acid per 100 c.c. of milk. 



The elective culture of Lactococcus takes place by allowing milk 

 to sour in a stoppered bottle at 20° to 25° C. and transfer it 

 repeatedly to boiled milk at that temperature. The thereby obtained 

 stocks of Lactococcus lactis are mostly anaerobic but specifically not 

 to be distinguished from the more aerobic forms which may be 

 produced by the same experiment. The acid mostly remains at about 

 8 c.c. of normal acid per 100 c.c. of milk, but may become 10 to 

 12 c.c. 



The elective culture of Lactobacillus succeeds best by cultivating 

 buttermilk in absence of air at 37 c to 40° C. and inoculating it into 

 boiled milk, at 30° C. and higher, the acidity can rise from 18 to 

 25 c.c. of normal acid per 100 c.c. of milk. 



The active lactic acid ferments are very variable; as factors of 

 hereditary constant variation are recognised cultivation at too high 

 or too low oxygen pressure, and cultivation at a temperature above 

 the optimum of growth. 



Lactic acid ferments do not lack in the intestinal flora, but play 

 there an inferior part. 



A considerable difference between Eastern anil Western lactic acid 

 ferments does not exist. 



Yoghurt and other such like sour milk preparations deserve the 

 attention of hygienists. 



Chemistry. — "On the course of the plaitpoint line and of the 

 spinodal lines, also for the case, that the mutual, attraction of 

 the molecules of one of the components of a binary mixture 

 of normal substances is slight", by Mr. J. J. van Laar. (Com- 

 municated by Prof. H. A. Lorkntz). 



(Communicated in the meeting ol' April 2(1, 1907). 



1. In the latest volume of These Proceedings 1 ) Dr. Kkesom (also 

 in conjunction with Prof. Kamkrt.ixgii Onnes) stated some important 

 results, inter alia concerning his investigation on the special case that 

 one, e.g. a x , of the two quantities a x and a, is very small ; which is 



l ) Kameklingh Onnes and Keesom, These Proc, Dec. 20, 1906, p. 501— 508 [On 

 the gas phase sinking in the liquid phase etc. (Coram. 96h|]; Keesom, Ibid. p. 

 508—511 |On 1 1 ie conditions for the sinking etc. (Comm. 96c)]; Keesom, Ibid. 

 March 28, 1907, p. 660—664 (Comm. 96c continued); Kamerlingh Onnes and 

 Keesom, Ibid, of April 25, 1907, p. 786—798 [The case that one component is 

 a gas without cohesion etc. (Suppl. N°. 15)]. 



