1. Percentages of fat, solids not fat and protein were determined in over 700 samples of mixed milk from 15 herds during 1925–26. In the case of fat content, nine herds produced one or more samples below 3 per cent., one herd recording 25 per cent, of samples below this limit. With regard to solids not fat, twelve herds produced milk containing less than 8·5 per cent, on one or more occasions, the highest percentage of deficient samples recorded being 40.
2. Frequency distributions of fat, solids not fat and protein percentages in the samples analysed, are given, together with standard deviations, and mean percentages with probable errors for these three constituents.
3. Correlation tables of fat with solids not fat, and protein with solids not fat have been prepared, and graphs illustrating the variations are given.