492 
on this point is known to me. For the 
reasons stated a few minutes ago atrophy 
may also be omitted here. We pass by also 
the direct forms of cell death, to reach at 
once the consideration of the indirect forms. 
The accompanying table offers an anal- 
ysis of some of the principal varieties of 
structural change, which occur during indi- 
rect cell death. 
Indirect Death of Cells. 
A. Necrobiosis. 
1. Cytoplasmic changes. 
a. granulation. 
b. hyaline transformation. 
ce. imbibition. 
d. desiccation. 
e. clasmatosis. 
2. Nuclear changes. 
a. karyorhexis. 
b. karyolysis. 
B. Hypertrophic degeneration. 
1, Cytoplasmic.* 
a. granular. 
b. cornifying. 
ce. hyaline. 
2. Paraplasmic.* 
a. fatty. 
b. pigmentary. 
ec. mucoid. 
d. colloid, etc. 
3. Nuclear (? increase of chromatine). 
We begin, therefore, with necrobiosis. 
We may appropriately mention first those 
organs of which the existence is limited in 
time, such as the thymus and the fetal 
kidney (mesonephros or Wolffian body). 
These organs attain first their full differen- 
tiation ; their elements during the next 
phase die off, and finally are resorbed, 
most of the organ disappearing. In the 
same category of change belong the his- 
tories of the senile ovary and testis. An- 
other familiar illustration is offered by the 
notochord, which in the mammals totally 
disappears during the foetal period. The 
notochord cells undergo peculiar character- 
istic modifications, hence it is difficult to 
*T cannot venture to assert that these two divi- 
sions are valid, and not arbitrary. 
SCIENCE. 
[N. S. Von. XIII. No. 326. 
say whether or not there is degeneration in 
the strict sense. Cell-death on a large scale 
is a common phenomenon of the tissues. 
It occurs in cartilage both when the carti- 
lage is permanent and even more conspicu- 
ously when cartilage gives way to bone, the 
disintegration of the cartilage cells preced- 
ing the irruption of the bone forming tis- 
sues. It occurs among the bone cells after 
they are imbedded in their calcified matrix. 
It occurs in the ovary, where we desig- 
nate its result as atresia of the follicles. 
It occurs in the sebaceous glands as an ac- 
companiment of the process of their secre- 
tion. It occurs among the glands of the 
intestine as discovered by Stohr, and occurs 
normally, though not constantly, in the 
appendix, as recorded by Ribbert. It oc- 
curs in the epithelium of the human preg- 
nant uterus and in all the tissues of the 
human decidua reflexa. Other examples 
could be enumerated, but we may content 
ourselves with citing the constant destruc- 
tion of blood corpuscles, both red and white. 
Degeneration, in the stricter sense of an 
ante-mortem hypertrophic change of cell 
structure, is also of widespread occurrence 
in the healthy body. No case of so-called 
granular degeneration under strictly nor- 
mal conditions is known to me, though it 
seems quite credible that such cases should 
occur. On the other hand, the cornifying 
degeneration is very important and does 
occur in all three germ-layers, for we ob- 
serve it in the ectoderm of the skin, the 
entoderm of the esophagus and the meso- 
derm of the vagina. Hyaline degeneration 
of so striking a character as to have been 
termed pseudo-pathologicial takes place 
regularly in the ectoderm (outer epithe- 
lium) of the placental chorion. In the 
rabbit it occurs in the uterine glands, dur- 
ing pregnancy, causing most rapid histoly- 
sis, and it seems to me probable that some 
of the changes, which can be observed in 
the decidua of the pregnant human uterus 
