HISTOLOGY OF THE MAMMARY GLAND. 
287 
tinguished from the interstitial tissue infiltrated and surrounded with 
round cells. I seldom found the excretory ducts in an early stage of 
catarrhal inflammation ; here the subepithelial cells (germ cells) were 
proliferated and stratified, so much so that the cylindrical epithelium 
were either between them or above them (the proliferation cells), and, # 
therefore, removed to a far greater distance from the membrana pro¬ 
pria than under normal conditions. 
In the isolated epithelial cells lying between the layers of round 
cells, as well as in the groups of epithelial cells above the round ele¬ 
ments, we found “ triibe schwelling ” (clouded swelling). The lumen of 
the lacteal ducts, free from catarrhal affection is often found obstructed 
with round elements, the origin of which is to be sought in the sur¬ 
rounding parts affected with catarrhal inflammation. 
The alveoloe also presented different states of the catarrhal pro¬ 
cesses. In the subepithelial layer (germ stratum) we found an exten¬ 
sive hyperplasia, whilst the membrana propria was normal and distinct¬ 
ly perceptible. 
The lumen of the alveoloe was obstructed partly by an accumula¬ 
tion of round cells amongst which were scattered clouded epithelial 
cells, and partly by fine granular epithelial cells, and by several strata of 
round cells forced from the membrana propria, in consequence of which 
they occupy the centre of the lumen. Seldom the reverse took place, 
the lumen of some alveoloe were filled with round cells, whilst the epith¬ 
elium remained quite normal, and not detached from the membrana 
propria as mentioned in the above cases. The question now presented 
itself, what caused the accumulation of round elements (pus-cells) in 
the lumen of the excretory ducts and alveoloe ? Virchow, Foster and 
Rindfleisch examined two forms of suppurative inflammation, viz., one 
only superficial (epithelial) in which the inflammation attacked princi¬ 
pally the epithelial layer, the other deeper (parenchymatous) which to¬ 
gether with the deeper tissue layers presented an inflammatory appear¬ 
ance, as the stratum mucosum et submucosum and so forth. Remark, 
Buhl and Eberth were of opinion that upon the epithelium pus-cells 
originated in an endogeneous manner. Cohnheim showed that blood 
was necessary for the formation of pus, since he proved that under cer¬ 
tain conditions colorless blood-corpuscles exuded from the capillaries, 
and in this manner furnished the material for the pus. 
From the above patho-anatomical changes in our cases, the pus- 
cells originated from the epithelial cells (germ cells) being in a state of 
proliferation, for we neither found changes in the membrana propria, 
