EXPERIMENTS ON ARTERIAL AND VENOUS BLOOD. 303
and shining bundles; in which statement he agrees with Emmert.
The results of the experiments of Berthold and Denis, and of one
experiment which I performed with the blood of a goat, have been
detailed at page 157; taking the mean of these results, it appears that
arterial contains more fibrin than venous blood in the proportion of
29 to 24. The greater softness of the fibrin obtained from venous,
as compared with that from arterial blood, might induce the suppo¬
sition that the fibrin undergoes some farther development in the
respiratory process; but the difference in consistence may be ex¬
plained by the circumstance of the fibrin existing in smaller propor¬
tion in venous blood, in consequence of which its particles must be
further separated from each other. The smaller proportion of the
fibrin in venous blood arises wholly, perhaps, from a part of the
fibrin of arterial blood being appropriated to the nutrition of the
tissues during the passage of the blood through the capillaries; it
may arise in part, also, from the lymph which contains fibrin in
solution being poured into the vascular system near the heart.
It is, however, probable that respiration does contribute to the
development of fibrin, and for these reasons:—First, that the blood
of the foetus contains a very small proportion of fibrin, though it is
an error to say it contains none; and, secondly, that in the morbus
cœruleus, which is dependent on malformations of the heart, such
as persistence of the canal in the ductus arteriosus, or of the fora¬
men ovale, tendency to hemorrhage (from deficient coagulability of
the blood?) has been observed. The remarkable tendency to he¬
morrhage from small wounds, which is sometimes witnessed, is,
however, an affection distinct from the morbus cœruleus. The
assertion of Denis, (Rech. exp. sur le Sang Humain. Paris, 1830,)
that venous blood contains less cruor than arterial blood, appears to
me to be merely an hypothesis; for there is no means of estimating
the number of red particles in any kind of blood. (See page 157.)
The evidence of different observers respecting the quantity of
water in the two kinds of blood is quite contradictory.*
From various analyses it appears, then, that there is less carbon in
the cruor of arterial blood than in that of venous blood, which would
*
agree very well with the theory of the excretion of carbon in the
form of carbonic acid by the lungs. Again, arterial blood contains
more oxygen than venous blood; and this fact would seem to be in
favour of the absorption of oxygen by the blood in the lungs. No
value, however, can be set upon these facts till they have been found
by repeated analyses to be constant, for a slight difference in the
drying of the substances to be analysed may make a great difference
in the results. (See also Lecanu, Etudes Chimiques sur le sang
Humain. Paris, 1837.)
The halitus of the blood seems to be an important part of this
fluid. But it is not known whether it differs in arterial and venous
blood.
* For an account of the different statements, see Burdach’s Physiol. Bd. iv. 383.