Franklin P. Mall 329 
pressure in it being practically zero. That the injection into the pulp 
is not a backward injection is proved by hgating one of the arteries to 
the spleen while making the experiment. The veins of the pulp of the 
region supplied by the closed artery were injected through the venous 
anastomoses within the lobule, but in this region the pulp-spaces were 
all empty. It is natural to conclude from this experiment that the 
blood passed from the ampullae into the pulp-spaces, then through the 
pores in the walls of the veins to form columns of blood discs which are 
pushed from the smaller to the larger veins of the spleen. ; 
The muscle of the fresh isolated spleen is easily paralyzed by inject- 
ing the artery with normal salt solution or even with ordinary aqueous 
solutions of gelatin. When fresh spleen is paralyzed in this way it 
is found by injecting gelatin and cinnabar granules, or by injecting 
whipped blood, specimens are obtained which are exactly identical with 
the experiments described above. I thought for a long time that the 
large number of cinnabar granules found in the lobular veins indicates 
that the granules pass in great part from the artery directly into the 
vein and in lesser part from the artery over into the pulp-spaces. But 
when the experiments are graded it is found that the granules do not 
enter the veins until the pulp-spaces are first filled. The same is true 
when artificial circulation is carried on with whipped blood. All the 
injections, especially those with asphalt and turpentine, confirm this 
view. In them numerous terminal arteries are found, around which 
the pulp spaces are injected, forming pictures much like bunches of 
grapes. From these the injection passes into the veins. Incomplete 
injections after the veins are plugged with granules are especially valu- 
able for the study of the relation of the arteries to the pulp-spaces. It 
imay be added that in all of these tests the greatest “ extravasation” of 
blood, of granules or of coloring matter is always immediately around 
the Malpighian follicles, showing that the communication between the 
ampullae and pulp-spaces are there the freest. 
The muscle of the spleen can be paralyzed in the living animal by in- 
jecting nitrites into it. In all of my experiments I injected nitrite 
of soda from one-half per cent to one per cent in strength. The latter 
solution paralyzes the muscle very quickly. In one experiment the 
upper, or larger end of the spleen, was washed out with a half per cent 
solution through the vein with the artery closed for a period of five 
minutes. At the end of this time the upper part of the spleen was 
totally paralyzed and flabby. The artery was then opened for 25 min- 
utes, and to show that the circulation through the paralyzed portion was 
well established the blood was collected from the open vein, which was 
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