454 



STATE BOARD OF AGRICULTURE. 



July 11, 24 liours culture 



July 12, 24 hours after first neutralization . . 

 July 13, 24 hours after second neutralization 



Acidity . 



42° 

 4S° 

 38° 



Plate count. 



780,000,000 

 1,2,50,000,000 

 1,410,000,000 



Microscopic 

 count. 



2,250,000,000 

 2,380,000,000 

 1,980,000,000 



The weiglits jter loop agreed ninoh better in this ease, the averasre 

 (lata being 1.00, l.Oo and 1.81 nig. The counts, also, were more satis- 

 factory, but do not agree at all with the increasing plate counts. 



As a last test, a three-days'-old milk culture of Bacterium lactis acidi 

 was counted microscopically on five sets of cover-glasses to determine the 

 probable error of microsco]>ic counts of milk cultures. The milk was 

 neutralized before being weighed out. Duplicate determinations gave 

 the milk per loop 1.83 and 1.89 mg. The microscopic counts gave the 

 following data: 



1,960,000,000 



2,240,000,000 



2,360,000,000 



2,400,000,000 



2,520,000,000 



The greatest error is approximately 28%. 



The results are altogether u^nsatisfactory, and the data are not con- 

 sistent enough to warrant a substitution of this method for the plate 

 method. The reascm is probably to be sought in the general inaccurary 

 of the loop as measure, together Avith the impossibility of obtaining 

 comparable data from curde<l milk. Considering also that young cultures 

 cannot be counted at all by the microscopic method on account of too 

 small numbers, all counts were continued by the plate method. 



I\-. FERMENTING CAPACITY OF VARIOUS STRAINS OF BACTERIUM LACTIS ACIDI. 



The formula for the fermenting power, according to subtitle IT, is 



J>_ 



5 log a 



^~ t (b—a) log 2 



It shows that four data are needed for the comi)utation : aS' = the 

 total amount of iirodncts formed, t = the time of experiment, and the 

 initial and final number of bacteria a and h. Though these data are 

 easily determined, there are only very few ex])eriments to be found in 

 the current literature that give all of these four data. In fact, as far 

 as the lactic bacteria are concerned, the author succeeded in linding 

 only one series of experiments complete enough to allow the computa- 

 tion of the fermenting power. Marshall and Farrand* in their experi- 

 ments on the association of the lactic organisms give a large number 

 of data with ]»ure cultures of Tiacter'nini hicti.s (ici'li which are compiled 

 in Table III. 



♦Marshall and Farrand, Special Bui. 42, Mich. Agric. Collefje, 1908. 



