nsurveyable. According to the new and
complete compilation of Reinert and v. Limbeck, the following figures
(calculated roundly for mm.^{3}) may be taken as physiological:

_Men._

Maximum Minimum Average
7,000,000 4,000,000 5,000,000

_Women._

Maximum Minimum Average
5,250,000 4,500,000 4,500,000

This difference between the sexes first makes its appearance at the time
of puberty of the female. Up to the commencement of menstruation the
number of corpuscles in the female is in fact slightly higher than in
the male (Stierlin). Apart from this, the time of life seems to cause a
difference in the number of red corpuscles only in so far that in the
newly-born, polycythaemia (up to 8-1/2 millions during the first days of
life) is observed (E. Schiff). After the first occasion on which food is
taken a decrease can be observed, and gradually (though by stages) the
normal figure is reached in from 10-14 days. On the other hand the
oligocythaemia here and there observed in old age, according to Schmaltz,
is not constant, and therefore cannot be regarded as a peculiarity of
senility, but must be caused by subsidiary processes of various kinds
which come into play at this stage of life.

The influence which the taking of food exercises on the number of the
red blood corpuscles is to be ascribed to the taking in of water, and is
so insignificant, that the variations, in part at least, fall within the
errors of the methods of enumeration.

Other physiological factors: =menstruation= (that is, the single
occurrence), =pregnancy=, =lactation=, do not alter the number of blood
corpuscles to any appreciable extent. The numbers do not differ in
arterial and venous blood.

All these physiological variations in the number of the blood
corpuscles, are dependent, according to Cohnstein and Zuntz, on
vasomotor influences. Stimuli, which narrow the peripheral vessels,
locally diminish the number of red blood corpuscles; excitation of the
vasodilators brings about the opposite effect. Hence it follows, that
the normal variations of the number contained in a unit of space are
merely the expressions of an altered distribution of the red elements
within the circulation, and are quite independent of the reproduction
and decay of the cells.

=Climatic conditions= apparently exercise a great influence over the
number of corpuscles. This fact is impor