34

muscular development and to the lower condition of vitality that must follow
from the presence of a composition of the blood exhibiting the lower physiological
limits of such necessary constituents as hæmoglobin and floating proteids of the
plasma combined with a lower scale of arterial pressure.

      All these factors react not only on the muscular tissues but affect every
tissue of the body, and particularly the delicate mechanism of the central nervous
system.

      Mosso's work has taught us that fatigue has much more to do with changes
in the central nervous system than with mere fatigue of muscle-substance due
either to accumulation of waste-products or consumption of the reserve of
energy-producing material. It would, therefore, appear that in a condition in
which the metabolic chemical changes of the central nervous system are kept
continually on a low level—as in the Bengali—fatigue will be more easily and
readily produced. Such, indeed, is in accordance with our everyday experience
and such we believe to be an important factor in the causation of the lack of
energy and vigour which is characteristic of the race.

IV.—THE EVIDENCE OBTAINED FROM THE NITROGEN BALANCE IN
BENGALIS.

       In order to be in a position to measure the proteid intake of the different
persons investigated, a large number of the different kinds of food-stuffs had first
to be analysed.

       In carrying out this part of the work samples of each different food material
were obtained from the reserve store of articles actually used as food. The
percentage of each proximate principle was then determined; the following table
gives the average results of the estimations. Analyses published by other
authorities are added for comparison :—

Table X.