MARcH 29, 1901.] 
ought also to be-regarded as cases of hya- 
line degeneration. That fatty degeneration 
takes place normally has long been taught. 
There seems no reason for regarding the 
development of ordinary or mesenchymal 
fat-cells otherwise than as instances of nor- 
mal degeneration. In old age a more or 
less marked fatty degeneration may be wide 
spread and occur in many different kinds 
of cells. The same is true of the deposit 
of pigment, as we see it in the liver cells 
and motor nerve cells of adults. Finally, 
mucoid and colloid degeneration are so ob- 
viously normal, that we commonly think of 
their pathological occurrence as merely an 
exaggeration of a normal state. 
The various kinds of changes in dying 
cells, with which the pathologist is most 
familiar, recur in healthy tissues. In the 
preceding table seven forms of change are 
enumerated under the heading ‘ necrobio- 
sis.’ Every one of these seven occurs nor- 
mally. Granulation of the bodies of the 
cartilage cells and of the notochord cells 
may be observed to precede their resorp- 
tion. Hyaline transformation is conspic- 
uous in the decidua reflexa. Imbibition 
or cellular cedema occurs in the epidermis 
of the lips, in the cells of the uterine glands 
during pregnancy after they have detached 
themselves from the gland walls; and in the 
endothelium of placental blood vessels of the 
rabbit. Desiccation is the usual accompani- 
ment of cornification. Clasmatosis has 
given its name to the clasmatocytes of 
Ranvier, and we may well apply the same 
term to the cells of the secreting milk 
gland, and also, asan unpublished research 
indicates, to the cells of the secreting glands 
of the cervix uteri. Karyolysis is, accord- 
ing to present probabilities, the method by 
which nucleated red blood cells are con- 
verted into non-nucleated blood-corpuscles. 
Karyorhexis, or the fragmentation of the 
nucleus, occurs in the cells of the disap- 
pearing follicles of the ovary. 
SCIENCE. 
493 
Lastly as to the removal of cells. The 
sloughing off of cells is one of the most 
familiar phenomena, since it occurs inces- 
santly over the epidermis and with the 
hairs; its part in menstruation and its 
colossal réle in the afterbirth are known 
to all, and every practitioner is accustomed 
to look for shed cells in urinary sediment. 
Large numbers of cells are lost by the 
intestinal epithelium. Cells without access 
to the external world must be got rid of 
by resorption, which seems to take place 
either with or without the cooperation of 
leucocytes. In the latter case we must for 
lack of a better hypothesis attribute the 
resorption to chemical means. Of resorp- 
tion with the aid of leucocytes the ne- 
crosed human decidua reflexa offers a 
perfect illustration. Of resorption with- 
out leucocytes the masses of degener- 
ated epithelium in the placenta, peripla- 
centa and obplacenta of the rabbit afford 
by far the most impressive demonstration 
I have ever seen. At nine days after 
conception the epithelium is profoundly 
changed, being very much thickened, and 
where thickened transformed into a syncy- 
tium without cell boundaries, but with an 
enormously increased number of nuclei. 
In the obplacenta (or portion of the uterine 
wall opposite the placenta proper) portions 
of the epithelium from the fundus of the 
glands remain, but the upper stratum has 
not only undergone syncytial degeneration, 
but has become vacuolated and partly re- 
sorbed without being directly attacked by 
either leucocytes or epithelium or any other 
kind of cells. At eleven days the resorp- 
tion has progressed still farther, so that the 
degenerated part is almost gone, but mean- 
while the isolated patches of epithelium 
have spread until they have united and so 
reformed a continuous epithelium. At thir- 
teen days the epithelium has reconstituted 
new glands or follicles, very unlike, how- 
ever, those of the resting uterus. To ex- 
