316 The Circulation through the Dog’s Spleen 
bar in die Milzvenenplexus einmiinden. Damit ist der Weg gegeben, 
welchen die zelligen Elemente des Blutes nehmen, wie auch die Erfah- 
rungen beziiglich der vendsen Hyperimie bestitigen. Es besteht somit 
auch in der Milz ein geschlossenes Gefiasssystem. Die Ergebnisse der 
Injectionen gelésster Farbstoffe beweisen jedoch dass die Wandungen 
dieses Gefisssystems in héherem Grade durchlassig sind als die Wan- 
dungen anderer Gefiissverzweigungen. Es ist zu schliessen, dass normaler 
Weisse wihrend des Lebens ein Theil des Blutplasmas denselben Weg 
durch die Spaltriume der Milzpulpa stromt, welchen bei der Injection 
die gelésten Farbstoffe nehmen.” 
My own work upon the spleen® has led me gradually to conclusions 
similar to Thoma’s. In my preliminary communication, which ap- 
peared before Thoma’s last paper, the conclusions are almost identical 
with his regarding the circulation through the pulp. “ The microscopic 
anatomy shows that the ampullae and venous plexus have very porous 
walls which permit fluids to pass through with ease and granules only 
with difficulty. In life the plasma constantly flows through the inter- 
cellular spaces of the pulp cords, while the blood corpuscles keep within 
fixed channels.” Later on I found it necessary to modify this view 
somewhat, making the walls of the capillaries of the pulp still more 
porous. “ By studying numerous successful injections of the last third 
of the ampulla I find that its communication with the vein is not wide 
but is cut up with bridges of tissue passing across its lumen before it 
communicates with the vein (1900, p. 34). It appears as if in the 
neighborhood of the lymph follicles the walls of the ampullae are most 
porous (p. 35). Experiments show that if the muscle is paralyzed the 
blood dises enter the pulp-spaces, thus causing an hemorrhagic infare- 
tion (p. 36). It seems as if the pulp-spaces are in all cases filled through 
these openings in the walls of the veins. Yet I am unwilling to accept 
this explanation until further arguments are made to support it, but 
am rather inclined to the idea that the pulp is filled with blood passing 
through the openings in the walls of the ampullae (p. 39).” 
I do not quote the instances in which I brought forward arguments 
in favor of a closed circulation, but only those in which the closed chan- 
nel was doubted. The reason for this will become apparent when I 
discuss some new specimens and experiments I have made recently. 
Two years ago Weidenreich * published an extensive and excellent criti- 
*Mall, Johns Hopkins Hospital Bulletin, 1898; Zeit. fiir Morphol. u. Anthropol., 
Stuttgart, 1900; and Spleen, Reference Handbook of Medical Sciences, New York, 
1903. 
3 Weidenreich, Arch. f. mik. Anat., LVIII, 1901. 
