Franklin P. Mall pow 
in 5 seconds, and it is usually found that the spleen does not show the 
faintest sign of contracting when it is laid upon a glass plate. When it 
is simply removed from the body without the injection of formalin it 
contracts during a period of several minutes and gradually expels all of 
the blood from the pulp and veins. 
In order to make this experiment more definite I used the very hyper- 
aemic spleen, found during active digestion. The animal was placed 
under the influence of morphine and the hyperaemic spleen drawn gently 
through an opening made in the abdominal wall. Next ten cubic centi- 
meters of the strongest formalin were rapidly injected into several por- 
tions of the spleen with a hypodermic syringe and then the organ was 
severed from the body with one stroke of the scissors. After the spleen 
was observed for 5 minutes in order to see that it had been completely 
paralyzed it was hardened in formalin. The sections which were sub- 
sequently made showed that the whole pulp was filled with blood, just as 
is the case in the salmon’s spleen or the dog’s spleen when the muscle is 
paralyzed for a greater length of time. This differs from the rest of the 
experiments in one most important respect—the blood was caught in posi- 
tion in the pulp of the normal hyperaemic spleen. There can be but one 
interpretation of this experiment—the blood passes through the pulp- 
spaces in normal circulation, and due to the rapid fixation and paralysis 
of the muscle it is held there. 
The crucial experiment is made by fixing the spleen in the living 
animal by injecting formalin directly into the carotid artery. For this 
purpose the dogs were fed four hours before the experiments in order 
that their spleens should be very hyperaemic. The cannula was intro- 
duced into the carotid artery pointing towards the heart and 2000 ce. 
of a 10 per cent solution of commercial formalin was injected at a 
pressure of 200 mm. Hg. This treatment coagulated immediately all 
of the tissues fixing definitely the chyle in the lacteals throughout their 
extent as well as all of the blood in the spleen. All of the muscles 
were immediately and completely paralyzed. The spleen remained 
very hyperaemic and showed no indication whatever to contract. Frozen 
sections showed that there are a great mass of red discs in the pulp 
especially around the Malpighian follicles. The distribution of the 
blood corresponds in every respect with that of cinnabar granules when 
injected either into the artery or the vein. At many points the veins 
are well filled with blood and at others the pulp and veins are so evenly 
filled with blood that the line between them cannot be seen. In gen- 
eral the spleen is nearly as full of blood as is the case when the vein 
has been ligated for half an hour. The effect of the formalin upon the 
