DAILY VARIATIONS. 



307 



TABLE LX VI .COMPOSITION OF MORNING AND EVENING MILK. 



(1897-1916.) 



It is seen that there is an average difference between morning 

 and evening milk of 0-35 per cent., but this is decreasing, as in 

 the first ten years of the period the difference was 0-4, and in the 

 last three years it has been about 0-2. The author showed that 

 before 1900 the distribution of fat percentages could be calculated 

 by the usual probability formula, assuming that the whole of the 

 results could be split up into two series equal in numbers having 

 mean percentages of fat of 3-59 and 4-00 (a difference of 0-41), 

 but in 1914 the distribution agreed fairly well with two series equal 

 in numbers having mean percentages of 3-57 and 3'84 (a difference 

 of 0-27), and, better still, with the assumption that the results 

 were split up in two series having mean percentages of 3-45 and 

 3-84 (a difference of 0-39), but that the higher percentage series 

 contained twice as many determinations as the other. 



For some reason, to which no cause has yet been assigned, it 

 appears that there is a gradually increasing tendency to produce 

 milk which approximates in composition at both milkings. 



Variations on Partial Milking. The first portions drawn 

 from the udder are known as " fore milk," the last portions as 

 " strippings " ; it is not unusual to find more than 10 per cent, 

 of fat in strippings. The quality of the milk drawn first from 

 the udder is very different from the last portions. Boussingault 

 has recorded the following analyses of milk drawn from a cow 

 in portions : 



