JOURNAL OF MICROSCOPICAL SCIENCE. 
EXPLANATION OF PLATES I, II, & III, 
Illustrating Mr. H. Marshall M^ard^s Paper on the Em- 
bryo Sac ind Development of Gymnadenia conopsea.^^ 
N. B. — Except vhen otherwise stated, the figures are generally from sections 
in absolute alcohol and glycerine, examined under Zeiss’s F, oc. 2 and 3. 
PLATE I. 
Fig. 1. — Optiial longitudinal section of young ovule, showing embryo- 
sac mother-cell, ind axial row of similar cells. This specimen and the next 
were examined ii the fresh state with traces of ammonic hydrate. 
Fig. 2. — Simiar section of slightly older ovule, of which the integument 
is more advance!, and the curvature more decided; the granular contents 
of embryo-sac nother-cell resist alkalis more than do the others. 
Fig. 3 — Actial section through older ovule seen from before. The 
second integument is well established, and following on the first. The 
embryo-sac moher-cell has had one “cap-cell” cut off, and a second 
division is takiig place to form the other. 
Figs. 4, 5, aid 6. — Longitudinal section through the embryo-sac. It is 
surmounted b^ two “ cap cells,” wliich, together with the surrounding 
layer of nuclei s-cells, are gradually compressed by the enlarging sac. 
(Fig. 6 is somevhat oblique, but still shows cells of the axial row.) 
Fig. 7. — Sirilar section. Two large nuclei in the embryo.sac have 
resulted from dvision. Note traces of cap-cells, and of cells of the nucleus 
of the ovule anund. 
Figs. 8, 9, .nd 10. — Similar preparations ; showing divisions of the two 
nuclei of Fig. 7- Treated (alcohol specimens) with strong acetic acid and 
fuchsine. 
Fig. ll.-Similar section, showing division of upper nucleus. Two 
nucleoli in ech half. The section is slightly oblique. 
Fig. 12.— Similar section. The two nuclei at each end, and fixed in the act 
of dividing i planes crossing at right angles ; a large vacuole occupies the 
centre of th sac. Remains of the cap-cells as a refractive mass under the 
micropyle. 
Fig. l3,“Longitudinal .section through the ovule. There are four naked 
masse.s ofirotoplasm at each end of the sac. Note traces of cap- and 
nuclous-ces around. (Alcohol specimen treated with acetic acid and 
fuchsine.) 
Fig. li— The masses of protoplasm have arranged themselves in the 
upper pari of the sac as an “ egg-apparatus,” consisting of two bolster- 
shaped “fnergidm” supporting an “oosphere” (germinal or embryonic 
vesicle), ad a free nucleus, near which is a second. 
