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360 RECENT TIMES.
blood-current, he calculated the quantity of blood contained
in the body. By this somewhat imperfect method he arrived
at the result that the weight of the blood constitutes about
the twentieth part of the body-weight.* The discovery of
the blood-corpuscles, which were first detected by MAL­
PIGHI, threw great light upon the composition of the blood.
They were described by SWAMMERDAM as egg-shaped
structures, by MALPIGHI as coralloidal strings, and by
LEEUWENHOEK, who studied their form in different classes
of animals, as small, oval, flattened spheroids. HEWSON
thought that they contained each a small vesicle, and expressed
an opinion that they originated chiefly in the
spleen.
VlEUSSENS and CHIRAC were then already contemplating
a chemical examination of the blood. A. BADIA and
MENGHINI showed conclusively that the blood contains
iron. F. QUESNAY—who, as the founder of the physio- J
cratic system, rendered the highest services to political J
economy—taught that the blood contains the following |
constituent parts:—1. Water; 2. Albuminous matters
which coagulate by heat, and when putrid develop an
alkaline, acrid quality ; 3. Fats which solidify in the cold,
but at a higher temperature are fluid, and generate a rancid |
acridity; 4. Gelatinous matters; and 5. Bitter saponaceous |
substances.t HEWSON continued to investigate the
physical and chemical properties of the blood, and gave
very great attention to the subject of its coagulation, the
causes of which he was at pains to work out by means of
various experiments.^ An opportunity was often afforded |
during venesection of observing that blood takes on a
redder colour when it comes into contact with air ; and the
ancients even were aware of the fact that arterial blood is
* Philosophical Transactions, London 1687, Decemb., No. 191, p. 433 «f
seq.
t F. QUESNAY: Essai physique sur l'economie animale, Paris 1747, ii, .34*2
et seq., iii, 31 el seq.—HAESER op. cit. ii, 592.
X WILL. HEWSON : On the Blood, G>.rm. transl., Niirnberg, 1870.—E. 1
BRUCKE : Vorlesungen iiber Physiologie, Wien 1885, i, 81 et seq.