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vacuole {^gs. ijo-ijj) which becomes more or less modified
as development proceeds.

In the mature embryo-sac of Micramfelts the various organs
are quite prominently displayed. The egg-apparatus consists
of a conspicuous oosphere and two very bulky synergids, in
which there is rather less vacuolization than is evident in most
of the forms. The antipodals are more conspicuous here
than in any of the preceding species {Jig^ 155)* The cyto-
plasm which surrounds the endosperm nuclei presents a finely
vacuolated appearance, but at no time was any starch ob-
served in it. The polar nuclei were not observed to fuse, but
they were found in contact at the time just preceding the
fertilization. As the embryo begins to form, the endosperm
rapidly expands and the cytoplasm assumes a much more
dense and compact character in its upper portion, and numer-
ous nuclei are scattered through it (^fig* 156). As develop-
ment proceeds, however, its structure becomes more open and
it has begun to encroach upon the nucellar tissue {Jig* iST)*
Up to this time no walls have been formed between the nuclei,
but this condition does not last long. The endosperm early
becomes a solid cellular mass {fig. ijS), in form wedge-shaped
and often easily dissected out of the ovule. In this condition
the mass makes rapid inroads upon the nucellus, the cells of
which show the effect of some disintegrating agent wherever
in contact with the endosperm. This disintegration appears
in the swelling of the cell-walls and the breaking up of the



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protoplasm of the cells. The process of cell-formation is
initiated in the region near the embryo and the more distant
parts are the last to become transformed. The compact
character of the upper and peripheral portions of the endo-
sperm, is apparent only in the earlier stages ; that which is
found later being of a much more open nature {Jig* ^59)-
The expansion of the ovular tissue proceeds rapidly and
by the time the endosperm has reached the cellular state {fig.
ij8) the ovule has almost arrived at mature proportions.
The first divisions of the oospore are transverse (Jig. ij6)
and the suspensor consists usually of two cells, the third a
terminal cell constituting the proembryo. The cleavages
which follow in the proembryo are more or less irregular
(Jig. /J7 a). The subsequent divisions give rise to a pyriform
mass of cells crowded into the apex of the nucellus. The
external differentiation of the embryo proceeds as in the other
cases cited, and the origin of the cotyledons is evident before
any interval differentiation is apparent (Jig. ijp).

Coccinia

Owing to the difficulty experienced in growing this form
the material obtained was but fragmentary. Hence only a
glance can be taken at the condition observed in some of the
earlier stages.

In this form, which is included in this tribe chiefly on ac-
count of the characters of the androecium, the ovules appear
upon the placenta as in the case of some of the Cucurbiteae
(see text-figure (5, Exo jF). In Coccinia^ as in some of the
previous cases, the character of the tissue in the apex of the
young nucellus makes it diflScult to identify the archesporium.
Only when the development of the megaspore-mother-cell is
well advanced, does it appear probable that the origin of the
tapetum and the primary sporogenous cell takes place after
the usual manner {fig* 139)* In the cases observed the spor-
ogenous cell appeared situated below an axial row of sterile
cells. In this as in previous cases the growth of the ovular
organs, integuments, etc., keeps pace with the internal differ-



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entiation, and there is no variation from the typical form
worthy of mention.

Cyclanihera

In the very young ovules the cells are arranged in confocal
series and the archesporial cell is not easily distinguished
from the others in size or other features (Jig* i6o) . Subse-
quently the spore-mother-cell appears quite distinct and the
tapetal cells to the number of two or more, separate it from
the epidermis {^g. i6i). At this time the initial stage in
the formation of the inner integument is visible in the usual
form of a slightly elevated ring due in some places to a radial
elongation of epidermal cells and in others to periclinal
divisions of the hypodermal elements {^g. i6i). In the sub-
sequent growth of the ovule the sporogenous cell becomes
deeply placed in the nucellus. The repeated divisions of the
original tapetal cells and the parietal series are evident. The
long axial series of cells thus formed is shown in figure 162.

The spore-mother-cell undergoes the usual divisions and
the fertile cell resulting is here also the lowermost of the series
{fg. i6j). The remains of the non-functional megaspores
are evident for some time around the distal end of the embryo-
sac.

In the development of the embryo-sac from this point on
only one early stage was observed. This was the two-cell
stage resulting from the division of the megaspore. There
is no indication of any irregularity in the process of develop-
ment. In figure 164 a nearly mature embryo-sac is shown
and this differs in no conspicuous way from those previously
cited. The egg-apparatus presents the usual appearance
with striated and vacuolated synergids. The antipodals are
evanescent and apparently devoid of any important function.

The cytoplasm surrounding the polar nuclei presents a
rather peculiar appearance {fig. 164). The coarser elements
of this cytoplasm are distributed in a radiating order around
the polar nuclei, which here are seen to be in contact. Bodies
with the aspect of vacuoles, whose limiting membrane stains
deeply and appears to be relatively thick, are quite conspicu-



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OU8. That these maybe in some sense an accidental feature,
due to some process in the preparation of the material, is pos-
sible, though this was the only place where they were found,
and the same methods were used in the preparation of the
material of Cyclanthera that were used in other cases. No
starch was observed in this or later stages.

After fertilization the endosperm nuclei increase in size and
multiply rapidly {Jig. i6fj^ and the mass as a whole expands
in the hollow form.



PART III. DISCUSSION AND CONCLUSIONS

The facts set forth in regard to the organogeny may be
summarized briefly as follows : The pistillate flower begins
as a lateral outgrowth, the apex of which becomes depressed
and then concave. The sepals arise first around the margin
of the torus and the petals follow on an inner circle, the mem-
bers alternating with the outer series. Within the circle of
petal-rudiments the carpels arise and become extended upward
to form the style. The placenta arises as a longitudinal ridge
upon which the ovules are borne laterally, except in the case
of Sicyosy in which the ovule is pendent from the top of the
ovary.

Of those forms whose development has been studied and
described above, it appears that Fevillea is the most primi-
tive. It is easy to see how all the others may have been de-
rived from such a form. Although, as Mtkller^ suggests, the
ovary of the Cucurbitaceae may have consisted originally of
five carpels, the simplicity of floral construction in FeoiUea^
in both staminate and pistillate flowers, points to the possible
course of evolution of the ovary of this family. With-
out entering at present upon a discussion of the difiicult
problem of the morphology of the androecium, some facts
have been observed in the ontogeny of the ovary which may
be discussed in this connection.

In the three tribes, Fevilleae, Melothrieae and Cucurbiteae,
the prevailing type of ovary is the tricarpellary form, and



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various degrees of specialization may be observed culmi-
nating in the fruit of Cucurbita Pepo. In the members of
these tribes we may note varying degrees of development of



(^m^




Fig. I. Development of the gynoednm. A\oF, Meloihria ; A, apex of
•hoot ; Bf Cf D, E, stages in the development of the ovary ; F, transverse
section of ovary. G to X', Bryonopsis; G, apex of shoot ; H, /, K^ devel-
opment of ovary ; J, section of ovary a little later than K. LtoO, Mamor-
dica ; X, apex of shoot showing two yonng pistillate flowers, x\MtNt young
pistillate flowers ; (7, section of ovary. P, apex of shoot and yonng pistil-
late flowers of TVichosanihes.

the spongy tissue which fills the locules of the ovary and
invests the seeds completely in certain genera {Cucurbita ^
CiiruUus). While the early stages in the ontogeny of the
ovary are very similar so far as observed throughout this



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family, those changes which mark the appearance of specific
and generic characters are soon apparent. The same charac-
ter may appear later in the ontogeny of the organs in one




Fig. 2. Development of the gynoednm. A to £, THchosanihes ; A, B^
C, D, stages in the development of the ovarj ; E^ section of ovary. F
to /, Luffa; F^ apex of shoot; G^ H, I, development of floral organs. /»
K^ Lagenaria; /, apex with two lateral floral mdiments ; K^ section ot
yonng ovary. L^ M^ Cucumis; Z, apex with young flowers; Jf, longitn^
dinal section of young ovary. N to 5", CitruUus; N^ apex; O, P, /?, 5,
longitudinal sections of young flowers showing origin of organs.

genus than in another, as for example in the filling of the
locules of the ovary by placental tissue. This occurs at an
early stage in most of the Cucurbitaceae, even before the
formation of the spore-mother-cell. In Fevillea the ovules



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are free in the locules until some time after fertilizatioi
there is no expression of a tendency toward the develo]
of spongy tissue until much later. The ovary of Fevi
in its earlier stages imperfectly divided into three locuh




Pig. 3. Development of the gynoecium. A to E^ Cucurbita Ft
apical region of shoot ; B^ Q D^ floral rndiments in longitudinal i
E, transTene section of young ovary. FtoJt similar stages in the i
ment of Cocdnia, JC to O, Micratnpelis ; K^ apex of shoot ; LtoC
tudinal sections through young ovary.

communication of the interior of the ovary with the e:
is maintained by the imperfect fusion of the ingrowing
to a much greater degree than is to be found in an]
form as Melothria^ Cucumis^ Cucurbita^ Sicyos or C



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thera. This weak development of the septa in the ovary of
Fevillea is still more significant when we consider the condi-
tion found in some related genera {Alsomitra^ Zanonia) in
which the ovary, composed of three carpels, is unilocular
and open to the exterior at the apex. The development of
placental tissue which finally fills the locules in Fevillea
occurs quite late and never to that degree found in members
of the Melothrieae and Cucurbitcae.

Among the Sicyoideae, Cocdtnia represents the condition
closely approximating that found in the preceding cases so far
as the structure of the ovary is concerned (see text-figure j).
The carpels unite to form the partitions, and the placentae in
the same manner as in the Cucurbiteae. In the case of Mi-
cramfelis^ however, only two carpels are apparent, each of
which produces, in our species, but two ovules. The margins
of the carpels form two longitudinal elevations which meet at
the center and become flattened against one another as in the
preceding cases, but instead of a row of ovules upon each
flank there appears but one, making four in the entire ovary.
While no evidence of more than two carpels has been found
in any of the young ovaries of Micramfelis examined, nor
of more than one ovule on the placental fold in any case, yet
it seems probable that the ovary of this form is derived by
the reduction of three carpels to two. We find in fact that
this form as well as others is subject to some variation, and
ovaries are frequently found in the mature state evidently
composed of three carpels, inasmuch as they contain three
locules and six seeds. But the prevailing number of locules
is two. We are reminded of the peculiar apron-like char-
acter of the placenta of Micramfelis in the development of
that organ in Luffa and others of the Cucurbiteae, in which
there is a downward prolongation of the placenta toward the
base of the ovary for a considerable distance beyond its in-
sertion. If in the case of Luffa but a single ovule were to
arise on each flank of this downward prolongation, we should
have a condition quite similar to that noticeable in the early
stages of Micrampelis. Inasmuch as we find at no stage in



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the development of the ovary of Micramfelis evidence of
aborted carpels or ovules, it may be questioned whether in
this form we have an ovary derived by reduction from one




Fig. 4. Development of the gynoecinm. A to /?, Micrampelis; A, B,
C sections through different r^ons, a, b^ c, of the ovary, D, E to O^
Sicyos; E, apex of shoot; F, G, H, clusters of rudimentary pistillate flow-
ers at different ages ; / to A^, longitudinal sections through young ovaries at
different stages ; Lto O, transverse sections through / at the regions indi-
cated by small letters. P to J^, Cydanthera; P, apex of shoot; R to V^
longitudinal sections of ovaries at di£krent ages; W^ transverse section
through ovary of about the size indicated by U,

having three or a greater number of carpels and a greater
number of ovules, but from the fact that the prevailing num-
ber of carpels in most of the members of this family is three



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it seems more reasonable to regard the ovary consisting of two
carpels as derived by reduction than as representing a more
primitive type. In the development of Sicyos there is distinct
evidence of such reduction (see text-figure 4). The earlier
stages of the development of the gynoecium are marked by the
appearance of three equidistant elevations on the torus, which
by their position and behavior, must be regarded as incipient
carpels. We have here a reduction in the number of func-
tional carpels as shown by the formation of a single placenta,
a case therefore quite similar to what might appear should
one of the three placental lobes of a form like Bryonopsis or
Coccinia bear a single ovule and the other placental lobes
become reduced or obliterated. While the ovules of Bryo-
no f sis and Coccinia are horizontal, it is quite probable that if
they were reduced to one as in the case of Sicyos its position
would be changed to the vertical.

Cyclanthera in a comparison with Sicyos would represent a
condition intermediate between that of Sicyos and a radially
symmetrical form such as Bryonopsis or Fevillea. If in the
ovary of Cyclanthera exflodens the two rows of ovules should
be replaced by a single ovule in vertical position, the condi-
tion would be entirely similar to that of Sicyos. In the indpi-
ency of the gynoecium three lobes may be recognized, though
not so distinctly as in Sicyos j and these soon become obliterated
in the stigma. It seems quite evident that the ovary of
Cyclanthera exflodens has also been derived from a tricarpel-
lary form. By the abortion of two of the three placental
ridges in a form like Bryonofsis a condition would result in
all essential respects similar to that existing in the ovary of
Cyclanthera explodens.

The growth of the placenta and the origin of the ovules
are matters of interest and are worthy of attention. Evi-
dently the simplest form of placentation is that in which
numerous seeds arise on parietal placentae in a unilocular
ovary {Alsoniitra). From this condition it is easy to trace the
gradual ingrowth of the edges of the carpels and the develop-
ment of the various features of placentation, already described



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to some extent. Text-figures 5 and 6 are- designed to rep-
resent some of these features.

The condition met with in Fevillea shows a step ii
of the parietal placentation in that the carpels have
toward the center of the cavity and have there bei








Fig. 5. PlacenUtiott. A, B, Fevillea, C, Melothria. D,
E, Mamordica, F, Trichosanthes, G to /, Luffa, K, Z,, Lagi
CilruUus, /, Cucumis,

tened by mutual contact. As may be seen, the ovu]
on rather long funicles, are in the earlier stage horia
in this respect the condition evident here is in no
different from that found in Melothria^ Bryonofsis
dica^ or Trichosanthes. In these latter forms the c
more numerous on each flank of the placenta.



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noted that in Luffa and other members of the Cucurbiteae,
and in Coccinia and Melothria^ the early condition of the
placentae is uniform, but a differentiation soon appears which
distinguishes one from another. Certain outgrowths from the




Fig. 6. Placentation. A to Z?, Cucurbita Pepo, showing origin of ovules
and their comparatiye development on the same placenta, D, E, F, Coc-
cinia, Gy H, Micrampelis. /, /, Sicyos. K^ Cydanihera*

placental flanks mark the point at which the ovules arise.
This is shown clearly in the case of Luffa^ and also in
Lagenaria and Cucurbita. In Luffa and Cucumis two ovules
arise on each flank, but in Lagenaria^ Citrullus^ and Cucur-
bita the number varies from two to several.



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As to the nature of the inferior ovary in the Cucurbitaceae,
Naudin** (1855) expressed the view that it was always wholly
or in part invaginated in the tissue of the peduncle, and that
the calyx is generally free from adherence to it. In support
of this position he cites cases where the calyx-lobes return to
foliar conditions with distinct laminae and petioles.

This view of the nature of the inferior ovary was not new
with Naudin. Schleiden^* (^846) after investigations on Rosa,
Leucojum^ Godeita^ JE^i^actis and some other plants, con-
cluded that the ovaries were formed entirely of the floral
axis ; furthermore that the carpels were only the upper part
of the ovary and that their tips run up to form the style and
stigma. According to his view the conception of the inferior
ovary as a fusion of the carpels with calyx and corolla was an
assumption unnecessary if not untenable. He points out that
in the development of the flower in Canna exigua and other
plants the invagination at the apex of the axis, which is the
beginning of the formation of the ovary, takes place before
there is any trace of the appearance of the perianth, and
further that in many cases the calyx and corolla are entirely
separate and stand free from the ovary. And so the ovary,
pistil and stigma represent modifications of no particular
organs but are sometimes of axial, sometimes of foliar
character.

Goebel,* however, in 1886, studied the development of
Pyrus Malus and shows that the carpellary leaves are laid
down in the young flower, but that the subsequent intercalary
growth of the zone on which they are inserted produces an
ovary ** lined inside by the insertions of the carpels." This
zone in a perigynous flower is but slightly widened. The
ovary of Pyrus Schleiden did not regard as truly inferior but
as representing a fusion of carpels and floral axis. Goebel,
however, regards it as the product of the growth of the bases
of the carpels and the zone upon which they are inserted.
All investigations upon the development of inferior ovaries,
he concludes, must reckon with the question as to how much
of the area of the base of the flower is occupied by the incipi-



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ent carpels. In the youDger stages, which show the first
laying down of the carpels, particularly in the Umbelliferae
and the Compositae, the carpels cover the whole of the inside
of the depression, and sometimes the gynoecium takes up the
whole of the vegetative point. In his words then it may be
summed up: " die Placentation im tiberstandigen und unter-
standigen Fruchtknoten eine ganz obereinstimmende, eine
Thatsache, die auf eine tlbereinstimmende Betheiligung der
Fruchtblatter in beiden Fallen hinweist.**

B. Schaefer^ (^890) traced the development of the ovary
in numerous plants, among which were the Campanulaceae.
The particular representative taken from that family was
Phyteuma nigrum^ in which he finds that the carpellary
** Anlagen" are laid down while the terminal concavity is yet
quite shallow and appear as two opposite elevations on a
slightly elevated ring extending to the base of the cavity.
Transverse divisions of the first two or three periblem layers
of cells at the sides of the base of the concavity elevate the
overlying tissues and so deepen the depression. He says
that the tissue which forms the covering of the ovarian cavity
appears as an outgrowth of the parietal placental folds. In
conclusion he says that the placentation in inferior ovaries,
which he investigated in the Compositae, Onagraceae and
Campanulaceae, is wholly in accord with that found in superior
ovaries. He carefully points out the course of develop-
ment in the different forms and maintains that the carpels
form a lining of the ovarian cavity, their backs being fused
with axial tissue. After quoting from GoebePs work, above
cited, he says : " So befand sich die Entwickelungsgeschichte
in schroffem Gegensatz zur Morphologie, welche auf Grund
theils von vergleichenden untersuchungen, theils von Miss-
bildungen zu der Annahme gekommen war, dass die Frucht-
blatter sich auch an der Bildung des Unterstandigen Frucht-
knotens betheiligen, indem sie, mit ihren Rilckentheilen an die
Axe gebunden, die Innenseite der Hohlung auskleiden."

The facts observed in connection with the development of
the ovary in the Cucurbitaceae, apparently support the conten-



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tion of Schleiden that the placentation is mainly of an axial
character and that the carpels contribute principally the upper
portion of the ovary and the style. Here also we are in accord
with the conclusions of Lestiboudois,*^ who studied the process
of development in Cucumis and Bryonia. He states that the
carpels appear as projections which elongate and finally close
the cavity before the formation of the ovules.

Furthermore, that the carpellary *<mamelons" are the
same in appearance as those which represent the sepals, pet-
als and stamens (staminodia). This appears most distinctly
in the case of Feoillea (^/. 58 y jig. d), but in all the other
cases it is to some extent apparent and in some more than in
others. After the first appearance of the carpels as minute
lobes on the peripheral surface of the torus, there is in every
case an accelerated growth of the periblem layers situated
just below the insertion of the carpels, that is, toward the
center of the torus. The growth of the ovary takes place
then mainly below the insertions of the carpels, the cells
around the bottom of the cavity retaining for some time a
distinctly mcristematic character. The bottom of the original
concavity which is indicated by the termination of the stylar
canal is in some cases {Luffa) far removed from the lower
end of the placenta in its later stages, the growth having oc-
curred mainly in the lower portion of the ovary. There is
no evidence of the fusion of the backs of carpels, either with
axial tissue or with portions of the perianth, and such an as-
sumption here seems unnecessary.

Text-figures 1-4. inclusive show the course of ontogenetic
development in the gynoecium as already described at length
in the treatment of the organogeny. The zone of growth
just below the insertion of the carpels is, in every case,
clearly apparent. In certain cases, as in Fevillea, the pla-
centa is evidently foliar in origin (text-figure 5, -^4), and
possibly in Sicyos (text-figure (5, /), but in all the others
examined it arises not from carpellary tissue but by a thicken-
ing, in certain definite regions, of the ovary wall.

The influence of the carpels is sometimes manifest in an



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earlier development of the oyules in their region than on
parts of the placenta more remote, as might be expected
where the function of seed-bearing has been transferred
gradually from sporophylls to axial tissue, though this con-
dition may be due to better nutrition. Too much emphasis
can hardly be laid upon the peculiar character of the pla-
centa in this family. We have noted the different forms
which the placenta assumes and the varied structure of the
ovary, and all the facts observed point to the placenta as a
center of variation. It is here that we find evidence of the



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