The uncertainty of the meaning of the cellular content in milk is apparently either a measure of the lack of differentiation of the cells occurring normally or abnormally in cow's milk, or it would seem to us, due to defective technic in the differentiation of those cells. The latter is shown by those laboratory workers who, while they believe in the smear method of examining milk, yet by failure to employ a differential stain, miss the point at issue. The latter has been demonstrated to us by the use of gentian-violet alone. In a previous article,1 we have shown that differentiation by any blood-stain such as the one we were using at the time, a 1 per cent. eosin methyl-alcohol followed by a 1 per cent. methylene blue methyl-alcohol, or its counterpart, the Jenner stain, or again the latter modifications of that stain, the Wright, and the one we