168 The American Naturalist. [February,. 
luteum that results from the rupture of the follicle is generally thought 
to be a growth of connective tissue, for the most part. J. Sobotta,’ 
however, finds that in the mouse this structure is formed by the en- 
largement of the epithelial cells of the follicle, aided by growth of con- 
nective tissue. His results are obtained from the very large numberof 
sections used in his previous study of the fertilization and cleavage of 
the mouse’s egg (See AMERICAN Naturauist Aug. ’95) and from the 
thousands of specimens at his disposal he is able to write a complete 
history of the corpus luteum. 
It is interesting to note that in three cases in which the egg was 
abnormally retained in follicles that had ruptured as usual when ripe 
the usual corpora lutea were formed, though of course the egg had not 
been fertilized. This and other reasons lead the author to affirm that, 
in the mouse, no distinction can be drawn between corpora lutea vera 
and corpora lutea spuria, that is to say the yellow body is just the same 
whether the egg is fertilized or not. 
The chief results of this paper may be summarized as follows: 
In the ripe Graafian follicle of the mouse the connective tissue sheath 
is composed of a fibrous outer part and of an inner coat of large, rounded 
cells; the many-layered epithelium internal to the latter shows mitotic 
divisions ; at the centre is the usual liquid bathing the discus proliget- 
ous that envelopes the egg. Both the connective tissue and the epithe- 
- lial layers are much thinned away on the side next the body-cavity 
where the rupture is to take place. 
When the follicle bursts it happens only exceptionally that blood 
escapes into its central cavity. The ruptured follicle is at first just 
like the ripe one except for the loss of the egg, discus proligerous, and 
the chief part of the liquid. The cleft in its side is very quickly healed. 
over by the union of its epithelial edges. 
About an hour after the rupture of the follicle the cells of the inner 
connective tissue sheath begin to divide by mitosis and liquid 1$ 
secreted into the central cavity. Migratory corpuscles appear in the 
inner connective tissue sheath. 
In from five to seven hours the growth of this sheath gives rise to 
fine radiating partition that penetrate the epithelial layers. The inner 
sheath is used up in the growth of these partitions as they extend 10 
through the epithelium to the central space; leucocytes are found all 
through the epithelial layers. 
After forty to fifty hours the liquid accumulated in the central space 
has been reabsorbed and its place taken by a small, gelatinous connec- 
? Archiv. f. Mik. Anat. 47, April, 1896, pp. 261-306. 
