326 The Circulation through the Dog’s Spleen 
He concludes from these experiments that the blood first passed 
into the pulp backward through the veins, and then when the lhgature 
was removed the blood passed into the veins again, by what mechanism 
he does not state. 
I have repeated these experiments a number of times and find that 
in the course of half an hour after ligature of the veins the spleen is 
distended to its maximum and the pulp is always gorged with blood, as 
described by Sokoloff and by Wicklem. If now the spleen is removed 
from the body by cutting its attachments to open all the large vessels, 
it empties itself at once, and sections show that the pulp is as free 
from red corpuscles as is the normal spleen. There must, therefore, 
be some mechanism by which the blood which enters the pulp either from 
the artery or the vein may be rapidly expelled from the pulp. In case 
the ligature from the vein is simply removed in the living animal the 
spleen does not become entirely anaemic, but when it is removed from 
the body it contracts to its maximum and expresses every drop of blood 
from its pulp. An extremely instructive experiment is made by keeping 
the vein ligated until the spleen is blue, but not distended to its maxi- 
mum. ‘This takes from 10 to 15 minutes. Then the spleen is to be 
removed from the body, leaving the hgature intact. The contractions 
begin at once and pump the blood around under the capsule, thereby giv- 
ing some large hemorrhagic spots in which the pulp is gorged with blood. 
At other points. however, the spleen is anaemic and practically normal. 
A portion of the spleen-pulp has been emptied of its blood, and due to 
the severe contraction it was passed to some other portion of the spleen 
to make it even more hemorrhagic than before. A double process has 
taken place, which can be observed with ease; the contraction has forced 
blood from the pulp into the vein in one portion of the spleen and from 
the vein into the pulp in another portion. At any rate one thing is defi- 
nite—when the blood is free in the pulp contraction of the muscle has 
the power to squeeze it out at once and to force it over into the vein. 
Miescher-Riisch,” in one of the best among the many excellent papers 
upon the spleen, states that in the dog the blood is pressed out of the 
pulp by the muscular contraction, while in the salmon, which has no 
muscle fibers in the spleen, the blood stays in the pulp-spaces. In the 
salmon, at any rate, the blood corpuscles must be flowing constantly 
through the pulp-spaces, forced onward by the arterial pressure. 
It is practically impossible to determine with certainty whether the 
blood circulates through the pulp-spaces of higher animals as it does in 
°° Miescher-Ruisch, Archiy f. Anatomie, 1881. 
