396 
J. SCHMIDT. 
In these cases the afterbirth is almost always very readily de¬ 
tached. So it has been at least with most of the cases which 
have fallen under my charge. 
This is strong evidence that no powerful contraction of the 
womb had become established, since otherwise the feebly at¬ 
tached placenta would have been expelled by the normal action 
of the uterus. Stockfleth* says also in harmony with this, that 
in cows attacked bv milk-fever the contraction of the uterus is 
wanting. 
Hereby the basis of both hypotheses is destroyed. The rapid 
' contraction of the uterus can neither cause, nor influence the 
cause of, the disease; on the contrary, this enfeebled contractility 
is itself a result of the disease. 
According to Franck’s hypothesis immediately after parturi¬ 
tion there should occur conditions which favor extreme blood 
pressure in the aorta. Is this really true ? 
If labor begins and the uterus as well as the muscular parieties of 
the abdomen contract, the blood must to some degree be carried from 
these to other portions of the body. The blood pressure must always 
then be greatest in the aorta, since the cardiac contractions expend 
their energy directly upon the blood stream within the aorta; the blood 
pressure in other parts of the body must decrease in proportion to the 
distance from the heart. During the birth pangs, as well as during 
other moments of impediment to the free passage of blood through vari¬ 
ous parts of the body, there must plainly be an increased arterial blood 
pressure ; after the cessation of the labor pains, however, the increased 
pressure must immediately cease. 
If, then, the birth act is completed, there occur permanent changes in 
the circulatory conditions, the great vacuum left in the uterus by the 
birth of the foetus becomes at once somewhat smaller, in part through 
the atmospheric pressure from without, partly through a mechanical 
contraction of the uterus brought about by the elasticity of the uterine 
tissues ; as far as permitted by the placenta and remaining placental 
fluids and blood, the space becomes filled with atmospheric air. The 
capillary network of the foetal placenta is in this way early subjected to 
a certain pressure, which also contributes to the prevention of a profuse 
haemorrhage from the thin walled capillary vessels here and there rup¬ 
tured during the birth throes. Shortly after birth the after pains also 
* Tidssh'iftfor Veterinafer, I. R. Bd. i 8 , S. 382 . 
