214 



SCIENTIFIC AGRICULTURE 



March, 1922. 



jDroduced under more ordinary conditions, 

 18 of 69 samples contained over 200,000 

 bacteria per cc, and 49 of the 69 samples 

 showed the presence of organisms of the 

 colon-aero genes group in 1 cc. 



As a result of his researches into the 

 bacterial quality of the milk of the City 

 of Manchester, Delepine (12) concluded 

 that ' ' good milk should not clot after being 

 incubated at 30 deg. C. for over 20 hours." 

 He has devised a very ingenious adapta- 

 tion of the "Fermentation Test" as a 

 means whereby a moderately rapid test for 

 the bacterial quality of milk may be con- 

 ducted. 



Milk "Clotting" Investigation. 



In view of the importance of the ques- 

 tion of milk spoilage, and in order that we 

 might secure data witli respect to the milk 

 produced in the Province of British Co- 

 lumbia, we commenced an investigation 

 some two years ago into the possible 'per- 

 iod of usability ' of milk ; and these resear- 

 ches are being pursued at the present time. 

 In consideration of the necessity for milk 

 in the diet, and particularly in the diet of 

 the child, and having in mind the finan- 

 cial aspect of tlie case, it would seem to be 

 a matter of considerable import that such 

 measures shall be adopted and put into 

 operation as will ensure that all milk shall 

 enjoy its 'maximum period of usability.' 

 For every hour that this 'period of usabil- 

 ity' is lessened or limited, the farmer and 

 the community suffer an economic loss. 

 In our work we have used to some extent 

 the classic laboratory metliods for the de- 

 termination of the bacterial content of 

 milk; but our principal activity has been 

 the conducting of 'clotting' experiments 

 by the adopting of the "Fermentation 

 Test". The observations which it is pos- 

 sible to record on tlie basis of these tests 

 involving 'mass action,' constitute a dis- 

 tinct commendation of tlie method. And, 

 we feel justified in hoping that eventually 

 it will be possible not only to secure spe- 

 cific data on the 'period of usability' of 

 milk, but that arising therefrom, we may 

 accumulate evidence with respect to the 

 associative action of bacteria as predicated 

 by Marshall, (13) and also be in a position 

 to discuss the specificity of mass fermenta- 

 tions. (Barthel), (14) (Gorini), (15.) Our 

 procedure is as follows: — Samples of the 

 milk to be tested are taken in sterile test 



tubes, incubated, and the mass reactions 

 recorded. As will be seen from the data 

 given herein, the incubators used are reg- 

 ulated to a temperature of 371/2 deg. C. It 

 is highly desirable that the work upon 

 which we are engaged shall be carried on 

 both at 371/^ deg C. and at a standard 'room 

 temperature.' Incubators suitable for the 

 latter temperature are expensive, and it is 

 only recently that we have felt justified 

 in securing such. 



For the present we can discuss the re- 

 searches pursued at four centres, A. B. C. 

 and D. In each centre, incubators 

 (3714 deg. C.) have been installed during 

 the period covered by the respective inves- 

 tigations. In some centres we have taken 

 samples of mixed milk, and also of the 

 milk of individual cows. The data pre- 

 sented immediately below, is concerned 

 solely with samples of mixed milk. 



A. At this centre we took 28 samples, 

 and all were incubated at 37 1^ deg. C. As 

 is to be expected, the time taken by the 

 respective samples to form the clot, varied. 

 The average of the recorded periods was 

 15.6 hours. 



B. At this centre we took 70 samples. 

 The temperature of the incubator varied 

 from 36 deg. C. to 38 deg. C. The shortest 

 period of time taken to form the clot was 

 15 hours, and the longest period occupied 

 in clotting ^A^^as 27 hours. The average of 

 the recorded periods for the 70 samples 

 was 21.4 hours. 



C. At this centre we took 143 samples, 

 and all were incubated at 371^ deg. C. 

 Three samples failed to clot in 24 hours. 

 With respect to the remaining 140 samples, 

 the shortest period in which the clotting 

 took place was 9 hours, and the longest per- 

 iod- required for the reactions was 22 



D. (a) At this centre we took 64 sam- 

 ples. The temperature of the incubator 

 varied from 35.5 deg. C. to 41 deg. C. The 

 shortest period in which the clotting took 

 place was 24 hours, and the longest period 

 required for the reactions was 48 hours. 

 The average of the recorded periods for 

 the 64 samples Avas 30.7 hours. 



The number of samples upon which we are 

 able to report is not sufficiently large to 

 warrant our advancing any definite or 

 final conclusions; bonce the results of the 



