The nourishment of the young animal during the
transition from intrauterine to independent life is a
function which, in itself, justifies the interest of
research workers in the mammary gland. However, the
selection of cattle for the production of milk in
quantities far in excess of the requirements of the
calf gives the mammary apparatus enormous èconomic
importance and, at the same time, stimulates investigation of the diverse problems surrounding milk secretion.
These problems have been studied by specialists
in the fields of pure physiology, of endocrinology,
of biochemistry and of genetics, and only by correlation of the work in all these fields will a true
picture of mammary function be obtained.
The effects of hormones on mammary function have
so far been studied only by post mortem examination
of the gland or by changes in volume and character of
the secretion. The experiments described in this
paper were carried out to determine if the more
direct index of action of endocrinological factors,
namely a measurement of change in metabolic characteristics, could be applied to the mammary gland. The
application of the technique of tissue metabolism opens
a highly interesting field of research and the experiments reported here are an evidence of the possibilities awaiting study.