

273 
is taken in the selection and measurement of the tubes, and in the 
thorough mixing of the diluted milk. Rarely have differences of ten 
per cent. occurred in duplicate determinations, and the general re- 
sults have not, as a rule, been more than three or four per cent. 
apart. ‘The number of globules represents the number counted in 
each field, the length of which in each case is 50 divisions of the 
micrometer scale. 
No. 1 : No. 2 No. 3 
Diameter of tube in div. of 
micrometer scale 48 72 60 
No. of No. of No. of 
globules. globules. globules, 
28 55 Si 
Of 69 48 
21 70 48 
34 56 46 
of Te 49 
31 07 56 
Average 31 65 46 
10000 7 

Applying the formula ——,,— to these averages and we have for 
reduction to standard diameter of 100 divisions by substituting the 
values above for . 
Tube No. 1 (Pome d=48 349.000 = 134 
Tube No. 2 n= 65 d= TR apugwe os 125 
Tube No. 3 n= 46 d=60 “ceeee ra 128 
Average for the three tubes 129 
This gives the number of globules in a tube whose diameter in di- 
vision of the micrometer scale is 100 and whose length is 50. Each 
division of the micrometer in the instrument used equals .0024 milli- 
meters. It follows that the capacity of this tube is .005425 cubic 
millimeters, and as the milk in this case was diluted to 50 times its 
volume this represents .0001085 cubic millimeters of milk. The 
number of globules in .0001 cubic millimeter of milk can, therefore, 
be found by dividing the number obtained above by 1.085, or by 
multiplying by .92. This gives 119. 
The relative size of the globules is found by dividing the per cent. 
of fat by the number of globules in .0001 cubic millimeter of milk, 
and, to avoid fractions, multiplying the result by 10000. The per 
cent. of fat in the milk taken for this example was 4.14. This gives 
for the relative size Tae wires oat rey eee 
The determinations thus far made have shown a marked difference 
in cows, both in the number and size of globules which their milk 
contains, and this difference can by no means be attributed to the 
breed alone; as, with the exception of the native cows, Ceres and 
Juno, all animals whose milk has been examined have been Jerseys. 
This is evident from the table below, in which appear the averages 
obtained from the milk of each animal tested. 
18 
