IQ 
KOFOID: DEVELOPMENT OF LIMAX. 00 
gradually accomplished, occupying in one instance recorded about five 
minutes, no trace of the extruded liquid is visible, I have observed in 
the two-cell stage the expulsion of the liquid at both animal and vegeta- 
tive poles, but never at both poles of an egg at the same time. Warneck 
(50) and Fol ('80) both state that the contents of the cavity are ex- 
pelled at the vegetativo pole. This is certainly by no means constant, 
and I am inclined to believe that in a majority of cases, espeeially in tho 
later stages, tho elimination takes place at the animal pole of the egg. 
This ephemeral cleavage cavity is not confined in Limax to the two- 
cell stage, but is equally prominent in tho stages immediately following. 
The passage of the egg from the two- to the four-cell stage may be 
accompanied by an incomplete elimination of the contents, for I have 
often observed cases where a small cavity persists throughout tho 
progress of this cleavage. 
Figures 8-13 (Plate I.) show the history of the cleavage cavity in a 
different egg from the one observed during the two- to four-cell stage. 
At 3.15 p. m. there was no trace of any cleavage cavity, and the second 
cleavage furrow had almost reached the vegetative pole. Half an hour 
later the characteristic four-cell condition had been reached (ERS), 
and in ten minutes more a cleavage cavity of considerable volume was 
developed in the vertical axis of the egg. This continued to increase in 
size until 4.45 p. m. (Figs. 9-11), when a total expulsion of the contents 
oceurred, occupying not more than thirty seconds (Fig. 12). The nuclei 
at this period were at the amphiaster stage. Within fifteon minutos a 
now cavity had appeared in the now elongated vertical axis of the egg. 
This cavity was at first very narrow and extended almost from pole to 
pole. It increased slowly in volume, but was not wholly obliterated at 
the division into eight cells, which occurred at 5.38-5.45 v. m. (Fig. 19). 
It is not at all unusual to seo the total elimination of the contents of 
the cavity at the division into eight cells, but the occurrence is not 
constant. The configuration of tho cavity of the four-cell stage as 
viewed from the animal pole is shown in Plate II. Fig. 17. It is almost 
rhomboidal in outline ; the angles lie at the cleavage planes, and the 
sides are curved with the convexity next the cavity. It is probable that 
a partial expulsion, or perhaps a total one, has already occurred, for 
the cavity was not very larpe and the nuelei were in the early phase 
of metakinesis when the eee was killed. When the cavity is nt its 
maximum it assumes very nearly a spherical shape, i. e. the bounding 
cells are concave toward the cavity, and they present more nearly the 
character of a wall of uniform thickness (Fig. E, p. 81). No case has 
