864 DR. E. KLEIN,” 
The spleen has been further regarded by some ‘physiolo- 
gists as an organ in which coloured blood-corpuscles are 
developed, and by others in which they are destroyed. Both 
theories are based on the fact that in the tissue of the pulp 
certain cellular elements—the pulp cells—are often found 
to contain coloured blood-corpuscles. The latter of these 
two theories is, in addition, supported by the fact that some 
of the pulp cells, besides enclosing coloured blood-corpuscles, 
contain also particles of hemoglobin and blood-pigment, 
thus indicating that coloured blood-corpuscles having been 
taken up by certain pulp cells (probably in consequence of 
these latter being ameeboid cells) are destroyed by them, so 
that finally only amorphous blood-pigment is left. The latter 
doctrine has been, moreover, greatly advanced by the 
discovery that the blood channels of the pulp are not repre- 
sented by a system of closed vessels, 7. e. vessels with a 
special wall, but that the terminal branches of all arteries— 
those that enter the pulp of the spleen as such, as well as 
those in relation with the Malpighian corpuscles—break up 
into a labyrinth of spaces penetrated by a delicate nucleated 
reticulum containing also lymphoid cells—the proper pulp 
cells ; on the other hand, the roots of the veins take their 
origin from those spaces. From this arrangement it is 
easy to understand that blood-corpuscles, while passing 
sluggishly through the labyrinth of the pulp, may be taken 
up by the pulp cells, and may become gradually destroyed. 
Likewise it can be readily explained why the efferent veins 
contain abundant colourless blood corpuscles; these, namely, 
being produced by the pulp cells, are simply carried away 
by the blood current, after having become separated from 
the pulp cells situated within the blood paths. 
Wilhelm Miller, Frey, and others, are the chief repre- 
sentatives of this doctrine of the distribution of the blood 
vessels, against Billroth, Schweigger-Seidel, Kolliker, 
Kyber, and others, who maintain that the blood-vessels of 
the pulp, like those of other organs, form a closed system of 
vessels with a definite wall and lumen, and that the reti- 
culum and the pulp cells—~. e. the parenchyma of the pulp— 
are always around, 7. e. outside, the vessels. 
The difference between the assertions of these two sets of 
authors is clearly a fundamental one, and doubtless that of 
W. Miller and Frey is much more favorable to the doctrine 
of the spleen pulp being concerned in the destruction of 
coloured and the production of colourless blood-corpuscles. 
‘. Billroth (Muller’s ‘ Archiv,’ 1857) was the first to describe 
the matrix of the pulp of the spleen as being composed of a 
