EXPERIMENT STATION BULLETINS. 



52» 



Red Polled (Pansy Belle) 



Grade 31 



Holstein (CoUecc Hoviwtje) 



Swiss (Collepe Kcckv) 



Holstein (College Belle) 



Grade 11 



Grade 17 



Grade 32 



Holstein (OUege Houwtje Mae). 



5/22 



9° 

 18° 



5° 

 13° 

 14° 

 17° 

 18° 



5/23 



]6°' 



11° 



]5"> 



6<» 



18° 



19° 

 14° 



From these tables it is safe to draw the conclusion that milk from different 

 animals varies widely, as also does milk from the same animal. 



Some notion may be gained from the mixing of milk which, too, is subject 

 to marked variation, but within more limited ranges. Richmond gives a table 

 on page 127 (loc. cit.) in which he states a mean monthly average of milk 

 for the past sixteen years. This does not illustrate accurately the composition 

 of mixed milk, but rather the greatest possible uniformity. 



Month. 



January. . . 

 February. , 



Mareh 



April 



May 



June 



July 



August 



September 

 October. . . 

 November. 

 December. 



Solids 

 not fat. 



8.86 

 8.85 

 8.83 

 8.82 

 8.84 

 8.80 

 8.73 

 8.71 

 8. 80' 

 8.92 

 8.89 

 8.88 



Mixed milk as Nve get it from the dairy usually is confined to a range of 14°-20° 

 acid with phenol-phthalein as indicator, and may most commonly be found about 

 18° acid. This is the general understanding among dairymen, hygienists, and 

 physiologists, and is not contrary to accepted belief. However, it has not been 

 sufficiently considered from the standpoint of the bacteriologists in its relation 

 to his work. 



It is now our purpose to add further confirmation and interesting bacteri- 

 olo,gical data to what has already been given. An instance of a mixed culture 

 of germs A + B will contribute to the same line of thought. 



Milk lot (dairy milk.) 



One. 



Original acidity 



Number of germs introduced per c. cm 



Germ A 



GermB 



Time of testing acidity 



Acidity 



Time of curding 



Temperatme maintained C 



19° 



766 

 1,520 

 96hrs. 



33° 

 130 hrs. 



20° 



Two. 



18° 



766 

 1,520 

 96 hrs. 



23° 

 336 hrs. 



20° 



Three. 



12° 



766 

 1,520 

 96 hrs. 



57° 

 96 hrs. 



20° 



Four. 



17° 



706 

 1,520 

 96 hrs. 



57° 

 144 hrs. 



20° 



Five. 



13° 



766 

 1.520 



90 hrs. 



02° 

 96 hrs. 



20° 



Irregular results are not very noticeable in this table, but there appears to 

 be a discrepancy between the acidity and the time of curding. This discrepancy 

 will probably be found one of the features of milk variation either due to the 

 composition of the milk or products arising from germ activity or perhaps 

 katalytic processes. 



Several tables which will now follow vary somewhat in the milk employed 

 and the germ planted. 



67 



