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ON THE

FERTILISATION OF ORCHIDS

BY

INSECTS,

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k

]Vo VAEIOUS CONTRIVANCES

THE

BY WHICH

ORCHIDS ARE FERTILISED BY INSECTS.

By CHAELES DAEWIN, M.A., F.E.S., &o.

SECOND EDITION, REVISED.

WITH ILLUSTRATIONS.

NEW YORK:
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1, 3, and 5 BOND STREET.
1886.

THE LIBRARY

BRIGHAM YOUNG UNIVERSITY

PROVO, UTAH

PREFACE

TO

THE SECOND EDITION.

The first edition of this work was published early in
the year 1862, and has been for some time out of print.
During the two or three years after its appearance
I received, through the kindness of various corre-
spondents in different parts of the world, a large
number of letters, especially from Fritz Miiller in South
Brazil, communicating to me many new and curious
facts, and calling my attention to some errors. Various
memoirs on the fertilisation of orchids have also since
been published, and I have myself examined several
new and striking forms. A. large amount of matter
has thus been accumulated; but the present volume
would be rendered much too long if the whole were
introduced. I have, therefore, selected only the more
interesting facts, and have given a brief abstract of
the several published papers. The work has thus been
remodelled ; and the additions and corrections are so
numerous that I have found it impossible to follow my
usual plan of giving a list of them. I have, however,

VI PREFACE TO THE SECOND EDITION.

appended, in chronological order, the titles of all the
papers and books on the fertilisation of the Orchideae
which have been published since the appearance of
the first edition of the present book. Finally, I will
remark that any reader who wishes merely to see how
wonderfully complex and perfect are the adaptations
for the fertilisation of these plants had better read
Chapter VII. on the Catasetidse. The account of
their structure and of the action of the several parts
will, I think, be intelligible, if he will first glance at
the explanation of the terms given at the close of
the Introduction.

List of Papers and Boohs hearing on the Fertilisation
of the Orchidese, which have been published since the
appearance of the First Edition of this Work in
1862, arranged in Chronological Order.

Bronn, H. G. — ' Charles Darwin, iiber die Einrichtungen zur Be-
fruchtimg britischer und auslanditcher Orchideen.' With
an Appendix by the Translator on Stanhopea devoniensis.
Stuttgart, 1862.

Gray, Asa. — On Platanthera (Habenaria) and Oymnadenia in
1 Enumeration of Plants of the Rocky Mountains.' — American
Journal of Science and Arts, Second Series, vol. xxxiv., No.
101, Sept. 1862, p. 33.

Gray, Asa. — On Platanthera hookeri, in a review of the first edi-
" tion of the present work. — American Journal of Science and
Arts, vol. xxxiv. July 1862, p. 143.

Anderson, J. — ' Fertilisation of Orchids.' — Journal of Horticulture
and Cottage Gardener, April 21, 1863, p. 287.

Gosse, P. H. — ' Microscopic Observation on some Seeds of Orchids.'
— Journal of Horticulture and Cottage Gardener, April 21,
1863, p. 287.

Gray, Asa. — On Platanthera (Habernaria) fiava and Gymnadmia
tridentata. — American Journal of Science and Arts, vol. xxxvi.
Sept. 1863, p. 292.

Journal of Horticulture and Cottage Gardener. — March 17,
1863, p. 206. * On Orchid Cultivation, Cross-breeding, and
Hybridising.'

Scudder, J. H. — On Pogonia ophioglossoides. Proceedings of the
Boston Society of Natural History, vol. ix. April, 1863.

Treviranus. — 'Ueber Dichogamie nach C. C. Sprengel und Ch.
Darwin. § 3. Orchideen.' — Botanische Zeitung, No. 2, 1863,
p. 9.

7111 LIST OF PAPERS AND BOOKS.

Treviranus. — ' Nachtragliche Bemerkungen titer die Befruchtung
einiger Orchideen.' — Botanische Zeitung, No. 32, 1863, p.
241.

Trimen, R. — 'On the Fertilisation of Disa grandiflora, Linn.' —
Journal of Linnean Society, Botany, vol. vii. 1863, p. 144.

West of Scotland Horticultural Magazine. — * Fertilisation of
Orchids,' Sept. 1863, p. 65.

Cbuger. — ' A few Notes on the Fecundation of Orchids, and their
Morphology.' — Journal of Linnean Society, Botany, vol. viii.
No. 31, 1864, p. 127.

Scott, J. — ' On the Individual Sterility and Cross-impregnation of
certain Species of Oncidium.' — Journal of Linnean Society,
vol. viii. No. 31, 1864, p. 162.

Moggridge, J. Traherne. — ' Observations on some Orchids of the
South of France.' — Journal of Linnean Society, Botany, vol.
viii. No. 32, 1865, p. 256.

Trimen, R. — ' On the Structure of Bonatea speciosa, Linn., with
reference to its Fertilisation.' — Journal of Linnean Society,
vol. ix. 1865, p. 156.

Rohrbach, P. — 'Ueber Epipogium gmelinV — Gekronte Preisschrift,
Gottingen, 1866.

Delpino. — ' Sugli Apparecchi della Fecondazione nelle Piante
antocarpee.' Florence, 1867.

Hildebrand, F.— ' Die Geschlechter-Vertheilung bei den Pflanzen,'
&c. Leipzig, 1867, p. 51, et seq.

Hildebrand, F. — ■ Frederigo Delpino's Beobachtungen tiber die
Bestaubungsvorrichtungen bei den Phanerogamen.' — Bota-
nische Zeitung, No. 34, 1867, p. 265.

Moggridge, J. Traherne, on Ophrys. — 'Flora of Mentone,' 1867 (?).
Plates 43, 44, 45.

Weale, J. P. Mansel. — ' Notes on the Structure and Fertilisation
of the Genus Bonatea, with a special description of a Species
found at Bedford, South Africa.' — Journal of Linnean Society,
Botany, vol. x. 1867, p. 470.

Hildebrand. — ' Notizen iiber die Geschlechtsverhaltnisse brasili-
anischer Pflanzen. Aus einem Briefe von Fritz Miiller.' —
Botanische Zeitung, No. 8, 1868, p. 113.

LIST OF PAPERS AND BOOKS. IX

Muller, Fritz.— ' Ueber Befruchtungserscheinungen bei Orchi-
deen.'— Botanische Zeitung, No. 39, 1868, p. 629.

Muller, Hermann. — ' Beobachtungen an westfalishen Orchideen.'
— Verbandlungen des nat. Vereins fiir Pr. Rheinl. u. Westf.
1868 and 1869.

Darwin, Charles. — ( Notes on tbe Fertilisation of Orchids.' —
Annals and Magazine of Natural History, Sept. 1869.

Delpino. — ' Ulteriori Osservazioni sulla Dicogamia nel Regno vege-
tale.' Parte prima. Milan, 1868-69, pp. 175-78.

Moggridge, J. Traherne. — ' Ueber Ophrys insectifera, L. (part).
— Verhandlungen der Kaiserl. Leop. Carol. Akad. (Nova
Acta), torn. xxxv. 1869.

Muller, Fritz. — ' Ueber einige Befruchtungserscheinungen.' —
Botanische Zeitung, No. 14, 1869, p. 224.

Muller, Fritz. — ■ Umwandlung von Staubgefassen in Stempel bei
Begonia. Uebergang von Zwitterbliithigkeit in Getrenntblu-
thigkeit bei Chamissoa. Triandrische Varietat eines monan-
drischen Epidendrum.' — Botanische Zeitung, No. 10, 1870,
p. 149.

Weale, J. P. Mansel. — ■ Note on a Species of Disperis found on
the Kageberg, South Africa.' — Journal of Linnean Society,
Botany, vol. xiii. 1871, p. 42.

Weale, J. P. Mansel. — ' Some Observations on the Fertilisation
of Disa macrantha.'' — Journal of Linnean Society, vol. xiii.
1871, p. 45.

Weale, J. P. Mansel. — ' Notes on some Species of Habenaria
found in South Africa.' — Journal of Linnean Society, vol. xiii.
1871, p. 47.

Cheeseman, T. F. — 'On the Fertilisation of the New Zealand
Species of Pterostylis.' — Transactions of the New Zealand Insti-
tute, vol. v. 1873, p. 352.

Muller, Hermann. — ' Die Befruchtung der Blumen durch Insekten,'
&c. Leipzig, 1873, pp. 74-86.

Cheeseman, T. F. — 'On the Fertilisation of Acianthus cyrtostilis.'
— Transactions of the New Zealand Institute, vol. vii. 1874
(issued 1875), p. 349.

X LIST OF PAPEES AND BOOKS.

Muller, Hermann. — ' Alpine Orchids adapted to Cross-fertilisation
by Butterflies/— Nature, Dec. 31, 1874.

Delpino. — * Ulteriori Osservazioni sulla Dicogamia nel Eegno
vegetale.' Parte seconda, fasc. ii. Milan, 1875, pp. 149, 150.

Lubbock, Sir J. — ' British Wild Flowers.' London, 1875, pp. 162-
175.

Fitzgerald, R. D. — 'Australian Orchids.' Tart I. 1875, Part II.
1876. Sydney, New South Wales.

CONTENTS.

Introduction Pages 1-5

CHAPTER I.

OPHRE.E.

Structure of the flower of Orchis mascula — Power of movement of
the pollinia — Perfect adaptation of the parts in Orchis pyra-
midalis — Other species of Orchis and of some closely allied
genera — On the insects which visit the several species, and on
the frequency of their visits — On the fertility and sterility of
various Orchids — On the secretion of nectar, and on insects
being purposely delayed in obtaining it 6-44

CHAPTER II.

opiire^: — continued.

Fly and Spider Ophrys — Bee Ophrys, apparently adapted for
perpetual self-fertilisation, but with paradoxical contrivances for
intercrossing — Herminium monorchis, attachment of the pol-
linia to the front legs of insects — Peristylus viridis, fertilisation
indirectly effected by nectar secreted from three parts of the
labellum — Gymnadenia conopsea, and other species — Habenaria
or Platanthera chlorantha and bifolia, their pollinia attached to
the eyes of Lepidoptera — Other species of Habenaria — Bonatea
— Disa — Summary on the powers of movement in the pollinia

45-79

xii CONTENTS.

CHAPTER III.

ARETHUSE-ffl.

Cephalanthera grandiflora ; rostellum aborted ; early penetration of
the pollen-tabes ; case of imperfect self-fertilisation ; cross-
fertilisation effected by insects which gnaw the labellum —
Cephalanthera ensi folia — Pogonia — Pterostylis and other
Australian orchids with the labellum sensitive to a touch —
Vanilla — Sobralia Pages 80-92

CHAPTER IV.

NEOTTE2E.

Epipactis palustris ; curious shape of the labellum and its import-
ance in the fructification of the flower — other species of Epi-
pactis— Epipogium — Goodyera repens — Spiranthes autumnalis ;
perfect adaptation by which the pollen of a younger flower is
carried to the stigma of an older flower on another plant —
Listera ovata; sensitiveness of the rostellum; explosion of
viscid matter; action of insects; perfect adaptation of the
several organs — Listera cordata — Neottia nidus-avis ; its
fertilisation effected in the same manner as in Listera — Thely-
mitra, self-fertile 93-127

CHAPTER V.

MALAXED AND EPIDENDRE^S.

Malaxis paludosa — Masdevallia, curious closed flowers — Bolbo-
phyllum, labellum kept in constant movement by every breath
of air — Dendrobium, contrivance for self-fertilisation — Cattleya,
simple manner of fertilisation — Epidendrum — Self-fertile Epi-
dendreae .. .. 128-148

CONTENTS. Xlll

CHAPTER VI.

YANDE2B.

Structure of the column and pollinia — Importance of the elasticity
of the pedicel ; its power of movement — Elasticity and strength
of the caudicles — Calanthe with lateral stigmas, manner of
fertilisation — Angra?cum sesquipedale, wonderful length of nec-
tary— Species with the entrance into the stigmatic chamber
much contracted, so that the pollen-masses can hardly be
inserted — Coryanthes, extraordinary manner of fertilisation

Pages 149-177

CHAPTER VII.

vande^e continued. — catasetid^e.

Catasetida?, the most remarkable of all Orchids — The mechanism
by which the pollinia of Catasetum are ejected to a distance and
are transported by insects — Sensitiveness of the horns of the
rostellum — Extraordinary difference in the male, female, and
hermaphrodite forms of Catasetum tridentatum — Mormodes
ignea, curious structure of the flowers ; ejection of the pollinia
— Mormodes luxata — Cycnoches ventricosum, manner of fer-
tilisation 178-225

CHAPTER VIII.

CYPRIPEDE.ffl — HOMOLOGIES OF THE FLOWERS OF ORCHIDS.

Cypripedium, differs much from all other Orchids — Labellum in
the form of a slipper with two small orifices by which insects
can escape — Manner of fertilisation by small bees of the genus
Andrena — Homological nature of the several parts of the flowers
of the Orchidese — "Wonderful amount of modification which
they have undergone 226-246

XIV CONTENTS.

CHAPTER IX.

GRADATION OF ORGANS, &C. — CONCLUDING REMARKS.

Gradation of organs, of the rostellnm, of the pollen-masses —
Formation of the caudicle — Genealogical affinities — Secretion
of nectar — Mechanism of the movement of the pollinia — Uses
of the petals — Production of seed — Importance of trifling
details of structure — Cause of the great diversity of structure in
the flowers of Orchids — Cause of the perfection of the con-
trivances — Summary on insect-agency — Nature abhors per-
petual self-fertilisation Page 247-293

Index 294

LIST OF WOODCUTS.

PAOE

1. Orchis mascula 8

2. „ „ pollinia of 12

3. Orchis ptramidalis 18

4. Moth's head and proboscis, with attached pollinia 3t.

5. Ophrys muscifera 46

6. „ aranifera .. 50

7. „ arachnites 51

8. „ APIFERA 53

9. Peristylus viridis 62

10. Gymnadenia conopsea 65

11. Habenaria chlorantha 69

12. pollinia of habenaria chlorantha and bifolia .. 74

13. Cephalanthera grandiflora 81

14. Pterostylis longifolia 87

15. Epipactis palustris « 94

16. „ latifolia 101

17. Spiranthes autumnalis 107

18. LlSTERA OVATA 116

19. Malaxis paludosa 130

20. Masdevallia fenestrata 136

21. Dendrobium chrysanthum 139

22. Cattleya 144

23. Diagram illustrative of the structure of the

Yandex 150

24. Pollinia of Vande^e 154

25. Pollinium of Ornithocephalus 160

XVI LIST OF WOODCUTS.

PAGE

26. Calanthe masuca 161

27. coryanthes speciosa 174

28. | J 182
VCatasetum saccatum <

29.) 1183

30. Catasetum tridentatum 194

31. MONACHANTHUS AND MyANTHUS 199

32. mormodes ignea 209

33. Cycnoches ventricosum 222

34. „ „ section through bud .. .. 223

35. Cypripedium 227

36. Transverse section of flower of an Orchid .. 236

37. Rostellum of Catasetum 256

38. Disc of Gymnadenia conopsea 272

P. S. — I am much indebted to Mr. G. B. Sowerby for the pains
which he has taken in making the Diagrams as intelligible as
possible.

ON THE

FERTILISATION OF ORCHIDS

BY

INSECTS,

&c. &e.

INTRODUCTION.

The object of the following work is to show that the
contrivances by which Orchids are fertilised, are as
varied and almost as perfect as any of the most beauti-
ful adaptations in the animal kingdom ; and, secondly,
to show that these contrivances have for their main
object the fertilisation of the flowers with pollen
brought by insects from a distinct plant. In my
volume * On the Origin of Species ' I gave only general
reasons for the belief that it is an almost universal law
of nature that the higher organic beings require an
occasional cross with another individual ; or, which is
the same thing, that no hermaphrodite fertilises itself
for a perpetuity of generations. Having been blamed
for propounding this doctrine without giving ample
facts, for which I had not sufficient space in that work,
I wish here to show that I have not spoken without
having gone into details.

I have been led to publish this little treatise sepa-
rately, as it is too large to be incorporated with any
other subject. As Orchids are universally acknow-
ledged to rank amongst the most singular and most

Z INTRODUCTION.

modified forms in the vegetable kingdom, I have
thought that the facts to be given might lead some
observers to look more curiously into the habits of our
several native species. An examination of their many
beautiful contrivances will exalt the whole vegetable
kingdom in most persons' estimation. I fear, however,
that the necessary details are too minute and complex
for any one who has not a strong taste for Natural
History. This treatise affords me also an opportunity
of attempting to show that the study of organic beings
may be as interesting to an observer who is fully con-
vinced that the structure of each is due to secondary
laws, as to one who views every trifling detail of
structure as the result of the direct interposition of the
Creator.

I must premise that Christian Konrad Sprengel, in
his curious and valuable work, ' Das entdeckte Geheim-
niss der Natur,' published in 1793, gave an excellent
outline of the action of the several parts in the genus
Orchis ; for he well knew the position of the stigma,
and he discovered that insects were necessary to remove
the pollen-masses.* But he overlooked many curious
contrivances, — a consequence, apparently, of his belief
that the stigma generally receives pollen from the
same flower. Sprengel, likewise, has partially described
the structure of Epipactis ; but in the case of Listera
he entirely misunderstood the remarkable phenomena
characteristic of that genus, which has been well de-
scribed by Dr. Hooker in the ' Philosophical Trans-

* Delpino has found (' Ult. Os- In this memoir Waefcher, who

servazioni sulla Dicogamia,' Part does not seem to have been ac-

ii. 1875, p. 150) a memoir by Waet- quainted with SprengePs work,

cher, published in 1801 in Roe- shows that insects are necessary

rner's ' Archiv fur die Botanik,' t. for the fertilisation of various

ii. p. 11, which apparently has re- orchids, and describes well the

mained unknown to everyone else. wonderful structure of Neottia.

INTRODUCTION. 3

actions' for 1854. Dr. Hooker has given a full and
accurate account, with drawings, of the structure of
the parts ; but from not having attended to the agency
of insects, he did not fully understand the object
gained. Kobert Brown,* in his celebrated paper in the
' Linnean Transactions,' expresses his belief that insects
are necessary for the fructification of most Orchids;
but adds, that the fact of all the capsules on a dense
spike not infrequently producing seed, seems hardly
reconcilable with this belief: we shall hereafter find
that this doubt is groundless. Many other authors
have given facts and expressed their belief, more or
less fully, on the necessity of insect-agency in the
fertilisation of Orchids.

In the course of the following work I shall have the
pleasure of expressing my deep obligation to several
gentlemen for their unremitting kindness in sending
me fresh specimens, without which aid this work would
have been impossible. The trouble which several of
my kind assistants have taken has been extraordinary :
I have never once expressed a wish for aid or for in-
formation which has not been granted me, as far as
possible, in the most liberal spirit.

EXPLANATION OF TERMS.

In case any one should look at this treatise who has
never attended to Botany, it may be convenient to
explain the meaning of the common terms used. In
most flowers the stamens, or male organs, surround in
a ring the one or more female organs, called the pistils.
In all common Orchids there is only one well-developed
stamen, which is confluent with the pistils, and they

* ' Linnean Transactions,' 1833, vol. xvi. p. 704.

4 INTRODUCTION.

form together the column. Ordinary stamens consist
of a filament, or supporting thread (rarely seen in
British Orchids), which carries the anther ; and within
the anther lies the pollen or male vivifying element.
The anther is divided into two cells, which are very
distinct in most Orchids, so much so as to appear in
some species like two separate anthers. The pollen in
all common plants consists of fine granular powder :
but in most Orchids the grains cohere in masses, which
are often supported by a very curious appendage, called
the caudicle. This part and all the other organs will
hereafter be more fully described and figured under the
head of the first species, Orchis mascula. The pollen-
masses, with their caudicles and other appendages, are
called the pollinia.

Orchids properly have three pistils or female organs,
united together, the upper and anterior surfaces of two
of which form the two stigmas. But the two are often
completely confluent, so as to appear as one. The
stigma is penetrated in the act of fertilisation by long
tubes, emitted by the pollen-grains, which carry the
contents of the grains down to the ovules or young
seeds in the ovarium.

The upper stigma is modified into an extraordinary
organ, called the rostellum, which in many Orchids
presents no resemblance to a true stigma. When
mature it either includes or is altogether formed of
viscid matter. In many species the pollen-masses are
firmly attached to a portion of the exterior membrane,
which, when insects visit the flowers, is removed,
together with the pollen-masses. This removable
portion consists in most British Orchids merely of a
small piece of membrane, with a layer or ball of viscid
matter underneath, and I shall call it the " viscid disc;"
but in many exotic species the portion removed is so

INTRODUCTION. O

large and so important, that one part must be called,
as before, the viscid disc, and the other part the pedicel
of the rostellum, to the end of which the pollen-masses
are attached. Authors have called that portion of the
rostellum which is removed, the " gland " or " retina-
culum," from its apparent function of retaining the
pollen-masses in their places. The pedicel, or pro-
longation of the rostellum, to which in many exotic
species the pollen-masses are attached, seems generally
to have been confounded, under the name of caudicle,
with the true caudicle of the pollen-masses, though
their nature and origin are totally different. The part
of the rostellum which is left after the removal of
the discs and viscid matter, is sometimes called the
" bursicula," or " fovea," or " pouch." But it will be
found convenient to avoid all these terms, and to call
the whole modified stigma the rostellum — sometimes
adding an adjective to define its shape ; that portion
of the rostellum which is removed with the pollen-
masses being called the viscid disc, together in some
cases with the pedicel.

Lastly, the three outer divisions of the flower are
called sepals, and form the calyx ; but, instead of being
green, as in most common flowers, they are generally
coloured, like the three inner divisions or petals of the
flower. In almost all the species, one of the petals,
which is properly the upper one, is larger than the
others and stands on the lower side of the flower, where
it offers a landing-place for insects, having been carried
round by the twisting of the ovarium. It is called
the lower lip or labellum, and often assumes most
singular shapes. It secretes nectar for the sake of
attracting insects, and is often produced into a spur-
like nectary.

6 OPHRE.E. Chap. I.

CHAPTEK I.

OPHRE^E.

Structure of the flower of Orchis mascula — Power of movement of the
pollinia — Perfect adaptation of the parts in Orchis pyramidalis —
Other species of Orchis and of some closely allied genera — On the
insects which visit the several species, and on the frequency of their
visits — On the fertility and sterility of various Orchids — Ou the
secretion of nectar and on insects being purposely delayed in
obtaining it.

Throughout the following volume I have followed, as
far as I conveniently could, the arrangement of the
Orchideae given by Lindley. The British species
belong to five of his tribes, the Ophreae, Neotteae,
Arethuseae, Malaxeae and Cypripedeae, but the two
latter tribes contain each only a single genus. Various
British and foreign species belonging to the several
tribes are described in the first eight chapters. The
eighth also contains a discussion on the homologies of
the flowers of the Orchideae. The ninth chapter is
devoted to miscellaneous and general considerations.

The Ophreae include most of our common British
species, and we will begin with the genus Orchis. The
reader may find the following details rather difficult
to understand ; but I can assure him, if he will have
patience to make out the first case, the succeeding ones
will be easily intelligible. The accompanying diagrams
(fig. 1, p. 8) show the relative position of the more
important organs in the flower of the Early Orchis
(0. mascula). The sepals and the petals have been re-
moved, excepting the labellum with its nectary. The

Chap. I. ORCHIS MASCULA. 7

nectary is shown only in the side view (n, fig. A) ;
for its enlarged orifice is almost hidden in shade in the
front view (B). The stigma (s) is bilobed, and con-
sists of two almost confluent stigmas ; it lies under the
pouch-formed rostellum (r). The anther (a, in B and
A) consists of two rather widely separated cells, which
are longitudinally open in front : each cell includes a
pollen-mass or pollinium.

A pollinium removed out of one of the two anther-
cells is represented by fig. C ; it consists of a number
of wedge-formed packets of pollen-grains (see fig. F,
in which the packets are forcibly separated), united
together by excessively elastic, thin threads. These
threads become confluent at the lower end of each
pollen-mass, and compose the straight elastic caudicle
(c, C). The end of the caudicle is firmly attached to
the viscid disc (cZ, C), which consists (as may be seen
in the section of the pouch-formed rostellum, fig. E)
of a minute oval piece of membrane, with a ball of
viscid matter on its under side. Each pollinium has
its separate disc ; and the two balls of viscid matter
lie enclosed together (fig. D) within the rostellum.

The rostellum is a nearly spherical, somewhat
pointed projection (r, figs. A and B) overhanging the
two almost confluent stigmas, and must be fully de-
scribed, as every detail of its structure is full of signi-
ficance. A section through one of the discs and balls
of viscid matter is given (fig. E ) ; and a front view of
both viscid dies within the rostellum (fig. D) is like-
wise given. This latter figure (D) probably best
serves to explain the structure of the rostellum ; but
it must be understood that the front lip is here con-
siderably depressed. The lowest part of the anther is
united to the back of the rostellum, as may be seen
in fig. B. At an early period of growth the rostellum

OPHRE.E.

Chap. I.

Fig. 1.

Okchis mascula

Chap. I. ORCHIS MASCULA. 9

Description of Fig. 1.

a. anther, consisting of two cells.
r. rostellum.
8. stigma.
I. labellum.

n. nectary.
p. pollen-mass.

c. caudicle of pollinium.

d. viscid disc of pollinium.

A. Side view of flowei', with all the petals and sepals cut off except the

labellum, of which the near half is cut away, as well as the upper
portion of the near side of the nectary.

B. Front view of flower, with all sepals and petals removed, except the

labellum.

C. One pollinium, showing the packets of pollen-grains, the caudicle, and

viscid disc.

D. Front view of the caudicles of both pollinia with the discs lying within

the rostellum, its lip being depressed.

E. Section through one side of the rostellum, with the included disc and

caudicle of one pollinium, lip not depressed.

F. Packets of pollen-grains, tied together by elastic threads, here extended.

(Copied from Bauer.)

) U OPHRE^E. Chap. 1.

consists of a mass of polygonal cells, full of brownish
matter, which cells soon resolve themselves into two
balls of extremely viscid semi-fluid matter, void of
structure. These viscid masses are slightly elongated,
almost flat on the top, and convex below. They lie
quite free within the rostellum (being surrounded by
fluid), except at the back, where each viscid ball
adheres to a small portion or disc of the exterior
membrane of the rostellum. The ends of the two
caudicles are strongly attached externally to these
two little discs of membrane.

The membrane forming the whole exterior surface
of the rostellum is at first continuous ; but as soon as
the flower opens the slightest touch causes it to rupture
transversely in a sinuous line, in front of the anther-
cells and of the little crest or fold of membrane (see
fig. D) between them. This act of rupturing makes
no difference in the shape of the rostellum, but con-
verts the front part into a lip, which can be depressed
easily. This lip is represented considerably depressed
in fig. D, and its edge is seen, fig. B, in the front view.
When the lip is thoroughly depressed, the two balls
of viscid matter are exposed. Owing to the elasticity
of the hinder part, the lip or pouch, after being
pressed down, springs up again and encloses the two
viscid balls.

I will not affirm that the rupturing of the exterior
membrane of the rostellum never takes place sponta-
neously ; and no doubt the membrane is prepared for
rupture by having become very weak along defined
lines ; but several times I saw the act ensue from an
excessively slight touch — so slight that I conclude
that the action is not simply mechanical, but, for the
want of a better term, may be called vital. We shall
hereafter meet with other cases, in which the slightest

Chap. L ORCHIS MASCULA. 11

touch or the vapour of chloroform causes the exterior
membrane of the rostellum to rupture along certain
defined lines.

At the same time that the rostellum becomes trans-
versely ruptured in front, it probably (for it was
impossible to ascertain this fact from the position of
the parts) ruptures behind in two oval lines, thus
separating and freeing from the rest of the exterior
surface of the rostellum the two little discs of mem-
brane, to which the two caudicles are attached exter-
nally, and to which the two balls of viscid matter
adhere internally. The line of rupture is thus very
complex, but strictly defined.

As the two anther-cells are open longitudinally
in front from top to bottom, even before the flower
expands, it follows that as soon as the rostellum is
properly ruptured from the effects of a slight touch,
its lip can be depressed easily, and, the two little discs
of membrane being already separate, the two pollinia
now lie absolutely free, but are still embedded in their
proper places. So that the packets of pollen and the
caudicles still lie within the anther-cells ; the discs
still form part of the rostellum, but are separate ; and
the balls of viscid matter still lie concealed within
the rostellum.

Now let us see in the case of Orchis musculo, (fig. 1)
how this complex mechanism acts. Suppose an insect
to alight on the labellum, which forms a good landing-
place, and to push its head into the chamber (see side
view, A, or front view, B), at the back of which lies the
stigma (s), in order to reach with its proboscis the end
of the nectary ; or, which does equally well to show
the action, push very gently a sharply-pointed common
pencil into the nectary. Owing to the pouch-formed
rostellum projecting into the gangway of the nectary,

12 OPHRE.E. Chap. I.

it is scarcely possible that any object can be pushed
into it without the rostellurn being touched. The ex-
terior membrane of the rostellurn then ruptures in the
proper lines, and the lip or pouch is easily depressed.
When this is effected, one or both of the viscid balls
will almost infallibly touch the intruding body. So
viscid are these balls that whatever they touch they
firmly stick to. Moreover the viscid matter has
the peculiar chemical quality of setting, like a
cement, hard and dry in a few minutes' time. As the
anther-cells are open in front, when the insect with-
draws its head, or when the pencil is withdrawn, one
pollinium, or both, will be withdrawn, firmly cemented
to the object, projecting up like horns, as shown (fig. 2)

Fig. 2.

A. Pollen-mass of 0. mascula, when I B. Pollen-mass of 0. mascula, after
first attached. the act of depression.

by the upper figure, A. The firmness of the attach-
ment of the cement is very necessary, for if the
pollinia were to fall sideways or backwards they could
never fertilise the flower. From the position in
which the two pollinia lie in their cells, they diverge a
little when attached to any object. Now suppose that
the insect flies to another flower, or let us insert the
pencil (A, fig. 2), with the attached pollinium, into

Chap. I. ORCHIS MASCULA. 13

the same or into another nectary : by looking at the
diagram (fig. 1, A) it will be evident that the firmly
attached pollinium will be simply pushed against or
into its old position, namely, into the anther-cell.
How then can the flower be fertilised? This is
effected by a beautiful contrivance : though the viscid
surface remains immovably affixed, the apparently
insignificant and minute disc of membrane to which the
caudicle adheres is endowed with a remarkable power
of contraction (as will hereafter be more minutely
described), which causes the pollinium to sweep
through an angle of about ninety degrees, always in
one direction, viz., towards the apex of the proboscis or
pencil, in the course of thirty seconds on an average.
The position of the pollinium after the movement is
shown at B in fig. 2. After this movement, completed
in an interval of time which would allow an insect to
fly to another plant,* it will be seen, by turning to the
diagram (fig. 1, A), that, if the pencil be inserted into
the nectary, the thick end of the pollinium now
exactly strikes the stigmatic surface.

Here again comes into play another pretty adapta-
tion, long ago noticed by Robert Brown.f The
stigma is very viscid, but not so viscid as when
touched by a pollinium to pull the whole off an insect's
head or off a pencil, yet sufficiently viscid to break
the elastic threads (fig. 1, F) by which the packets
of pollen-grains are tied together, and leave some of
them on the stigma. Hence a pollinium attached to
an insect or to a pencil can be applied to many
stigmas, and will fertilise all. I have often seen the

* Dr. H. Miiller (' Die Befruch- flowers of Orchis mascula, and

tung der Blumen durch Insekten,' finds that this statement is correct.

1873, p. 84) has timed humble- t ' Transactions of the Linnean

bees at work on the spikes of Society,' vol. xvi. p. 731.

14 OPHRE.E. Chap. I.

pollinia of Orchis pyramidalis adhering to the pro-
boscis of a moth, with the stump-like caudicles alone
left, all the packets of pollen having been left glued
to the stigmas of the successively visited flowers.

One or two other little points must be noticed.
The balls of viscid matter within the pouch-formed
rostellum are surrounded with fluid; and this is
very important, for, as already mentioned, the viscid
matter sets hard when exposed to the air for a very
short time. I have pulled the balls out of their
pouches, and found that they had entirely lost the
power of adhesion after a few minutes. Again, the
little discs of membrane, the movement of which, as
causing the movement of the pollinia, is so abso-
lutely indispensable for the fertilisation of the flower,
lie at the upper and back surface of the rostellum,
and are closely enfolded and thus kept damp within
the bases of the anther-cells ; and this is very neces-
sary, as an exposure of about thirty seconds causes
the movement of depression to take place ; but as
long as the disc is kept damp, the pollinia remain
ready for action whenever removed by an insect.

Lastly, as I have shown, the pouch, after being
depressed, springs up to its former position ; and this
is likewise of great service ; for if this action did not
take place, and an insect after depressing the lip
failed to remove the two viscid balls, or if it removed
one alone, then in the first case both, and in the
second case one would be left exposed to the air;
consequently one or both would quickly lose all
adhesiveness, and the pollinium would be rendered ab-
solutely useless. That with many kinds of Orchids
insects often remove only one of the two pollinia at
a time is certain; it is even probable that they
generally remove only one, for the lower and older

Chap. I. ORCHIS. 15

flowers almost always have both pollinia removed,
whilst the younger flowers close beneath the buds,
which will have been seldomer visited, have frequently
only one pollinium removed. In a spike of Orchis
maculata, I found as many as ten flowers, chiefly the
upper ones, w hich had only one pollinium removed ;
the other pollinium being still in its proper place with
the lip of the rostellum well closed up ; so that all the
mechanism was perfect for its subsequent removal by
some other insect.

When the first edition of this book was published,
I had not seen any insects visiting the flowers of
the present species ; but a friend watched some plants,
and saw them visited by several humble-bees, appa-
rently Bombus muscorum ; and Dr. H. Miiller * has seen
four other species of Bombus at work. He caught
ninety-seven specimens, and of these thirty-two had
pollinia attached to their heads.

The description now given of the action of the
organs in Orchis mascula applies to 0. morio, fusca,
maculata, and latifolia. These species present slight
and apparently co-ordinated differences in the length
of their caudicles, in the direction of the nectary,
in the shape and position of the stigma, but they
are not worth detailing. In all, the pollinia when
removed from the anther-cells undergo the curious
movement of depression, which is so necessary to
place them in a right position on an insect's head
for striking the stigmatic surface of another flower.
Six species of humble-bees, the hive-bee and two
other kinds have been seen by H. Miiller and myself
visiting the flowers of Orchis morio. On some of the

Die Befruchtung, &c, p. 84.

16 OFHIiE^. Chap. I.

hive-bees from ten to sixteen pollen-masses adhered ;
to the head of Eueera longicornis eleven, to the head of
Osmia rufa several, and several to the bare surface close
above the mandibles of Bombus muscorum. H. Muller
has seen twelve different kinds of bees visiting the
flowers of 0. latifolia, which are also visited by
Diptera. My son George observed for some time
plants of 0. maculata, and saw many specimens of a
fly (Empis livida) inserting their proboscides into the
nectary ; and subsequently the same fact was ob-
served by me. He brought home six specimens of this
Empis, with pollinia attached to their spherical eyes,
on a level with the bases of the antennae. The pollinia
had undergone the movement of depression, and stood
a little above and parallel to the proboscis : hence
they were in a position excellently adapted to strike
the stigma. Six pollinia were thus attached to one
specimen, and three to another. My son also saw
another and smaller species {Empis pennipes) inserting
its proboscis into the nectary; but this species did
not act so well or so regularly as the other in
fertilising the flowers. One specimen of this latter
Empis had five pollinia, and a second had three
pollinia, attached to the dorsal surface of its convex
thorax. H. Muller has seen two other genera of
Diptera at work on this orchis, with pollinia attached
to the front part of their bodies ; and on one occasion
he saw a humble-bee visiting the flowers.*

We now come to Orchis (sub-genus, Anacamptis)
pyramidalis, one of the most highly organised species

* M. M. Girard caught a front of its mouth : ' ADnale3 de

longicorn beetle, Stranyalia atra, la Soc. Entomolog. de France,'

with a tuft of the polleu-masses torn ix. 1869, p. xxxi.
of this orchis attached to the

Chap. I. ORCHIS PYRAMIDALIS. 17

which I have examined, and which is ranked by several
botanists as a distinct genus. The relative position of
the parts (fig. 3) is here considerably different from
what it is in 0. mascula and its allies. There are two
quite distinct rounded stigmatic surfaces (s, s, A)
placed on each side of the pouch-formed rostellum.
This latter organ, instead of standing some height
above the nectary, is brought down (see side view B)
so as to overhang and partially to close its orifice.
The ante-chamber to the nectary, formed by the
union of the edges of the labellum to the column,
which is large in 0. mascula and its allies, is here
small. The pouch-formed rostellum is hollowed out
on the under side in the middle : it is filled with
fluid. The viscid disc is single and of the shape of a
saddle (figs. C and E) ; it carries on its nearly flat
top or seat the two caudicles of the pollinia, the ends
of which firmly adhere to its upper surface. Before
the membrane of the rostellum ruptures, the saddle-
formed disc can be clearly seen to ha continuous with
the rest of the surface. The disc u partially hidden
and kept damp (which is of great Importance) by the
over-folding bases of the two anther-ceJls. It consists
of several layers of minute cells, and is therefore rather
thick ; it is lined beneath with a layer of highly ad-
hesive matter, which is formed within the rostellum.
It corresponds strictly to the two minute, oval, sepa-
rate discs to which the two caudicles of 0. mascula
and its allies are attached.

When the flower opens and the rostellum has
become symmetrically ruptured, either from a touch
or spontaneously (I know not which), the slightest
pressure depresses the lip, that is, the lower and bi-
lobed portion of the exterior membrane of the ros-
tellum, which projects into the mouth of the nectary.

18

OPHRE^.

Chap. I.

Fig. 3.

Orchis pyramidalis.

Chap. I. ORCHIS PYEAMIDALIS. 19

Description of Fig. 3.

a. anther.
s,$. stigma.
r. rostellum.

I. labellum.

V. guiding plate on the labellum.

n. nectary.

A. Front view, with all the sepals and petals removed, except the

labellum.

B. Side view, with all the sepals and petals removed, with the labellum

longitudinally bisected, and with the near side of the upper part
of the nectary cut away.

C. The two pollinia attached to the saddle-shaped viscid disc.

D. The disc after the first act of contraction, with no object seized.

E. The disc seen from above, and flattened by force, with one pollinium

removed ; showing a depression in its surface, by which the second
movement of the pollinium is effected.

F. The pollinia removed by the insertion of a needle into the nectary, after

the saddle has clasped the needle by the first act of contraction.

G. The same pollinia after the second movement and their consequent

depression.

20 OPHRE^E. Chap. I.

When the lip is depressed, the under and viscid surface
of the disc, still remaining in its proper place, is un-
covered, and is almost certain to adhere to the touch-
ing object. Even a human hair, when pushed into
the nectary, is stiff enough to depress the lip or
pouch ; and the viscid surface of the saddle adheres
to it. If, however, the lip be pushed only slightly,
it springs back and recovers the under side of the
saddle.

The perfect adaptation of the parts is well shown by
cutting off the end of the nectary and inserting a
bristle at that end ; consequently in a reversed direc-
tion to that in which moths insert their proboscides ;
and it will be found that the rostellum may easily be
torn or penetrated, but that the saddle is rarely or
never caught. When the saddle together with the
pollinia is removed on a bristle, the under ' lip in-
stantly curls closely inwards, and leaves the orifice of
the nectary more open than it was before; but whether
this is of much service to the moths which frequent
the flowers, and consequently to the plant, I will not
pretend to decide.

Lastly, the labellum is furnished with two pro-
minent ridges (T, figs. A, B), sloping down to the
middle and expanding outwards like the mouth of a
decoy ; these ridges serve to guide any flexible
body, like a fine bristle or hair, into the minute and
rounded orifice of the nectary, which, small as it
already is, is partly choked up by the rostellum.
This contrivance of the guiding ridges may be com-
pared to the little instrument sometimes used for
guiding a thread into the fine eye of a needle.

Now let us see how these parts act. Let a moth
insert its proboscis (and we shall presently see how
frequently the flowers are visited by Lepidoptera)

Chap. I. OKCHIS PYRAMIDALIS. 21

between the guiding ridges of the labellum, or insert
a fine bristle, and it is conducted safely to the minute
orifice of the nectary, and can hardly fail to depress
the lip of the rostellum ; this being effected, the
bristle comes into contact with the now naked and
sticky under surface of the suspended saddle-formed
disc. When the bristle is removed, the saddle with
the attached pollinia is removed. Almost instantly,
as soon as the saddle is exposed to the air, a rapid
movement takes place, and the two flaps curl inwards
and embrace the bristle. When the pollinia are
pulled out by their caudicles, by a pair of pincers,
so that the saddle has nothing to clasp, I observed
that the flaps curled inwards so as to touch each
other in nine seconds (see fig. D), and in nine more
seconds the saddle was converted by the flaps curl-
ing still more inwards into an apparently solid ball.
The proboscides of the many moths which I have
examined, with the pollinia of this Orchis attached
to them, were so thin that the tips of the flaps just
met on the under side. Hence a naturalist, who
sent me a moth with several saddles attached to its
proboscis, and who did not know of this movement,
very naturally came to the extraordinary conclusion
that the moth had cleverly bored through the exact
centres of the so-called sticky glands of some
Orchid.

Of course this rapid clasping movement helps to fix
the saddle upright on the proboscis, which is very
important ; but the viscid matter setting hard rapidly
would probably suffice for this end, and the real object
gained by the clasping or curling movement is the
divergence of the pollinia. The pollinia, being at-
tached to the flat top or seat of the saddle, project at
first straight up and nearly parallel to each other ;

22 OPHRE.E. Chap. I.

but as the flat top curls round the cylindrical and
thin proboscis, or round a bristle, the pollinia neces-
sarily diverge. As soon as the saddle has clasped the
bristle and the pollinia have diverged, a second move-
ment commences, which action, like the last, is ex-
clusively due to the contraction of the saddle-shaped
disc of membrane, as will be more fully described in
the ninth chapter. This second movement is the
same as that in 0. mascula and its allies, and causes
the divergent pollinia, which at first projected at right
angles to the needle or bristle (see fig. F), to sweep
through an angle of nearly ninety degrees towards the
tip of the needle (see fig. G), so as to become de-
pressed and finally to lie in the same plane with the
needle. In three specimens, this second movement
was effected in from thirty to thirty -four seconds after
the removal of the pollinia from the anther-cells, and
therefore in about fifteen seconds after the saddle had
clasped the bristle.

The use of this double movement becomes evident
if a bristle with pollinia attached to it, which have
diverged and become depressed, be pushed between
the guiding ridges of the labellum into the nectary
of the same or another flower (compare figs. A and
G) ; for the two ends of the pollen-masses will be
found now to have acquired such a position that the
end of the one strikes against the stigma on the one
side, and the end of the other at the same moment
strikes against the stigma on the opposite side. The
secretion on the stigmas is so viscid that when the
pollinia are withdrawn, the elastic threads by which
the packets of pollen are bound together are ruptured ;
and some dark-green grains may be seen, even by the
naked eye, remaining on the two white stigmatic sur-
faces. I have shown this little experiment to several

Chap. I. ORCHIS PYEAMIDALIS. 23

persons, and all have expressed the liveliest admiration
at the perfection of the contrivance by which this
Orchid is fertilised.

As in no other plant, or indeed in hardly any
animal, can adaptations of one part to another, and
of the whole to other organisms widely remote in the
scale of nature, be named more perfect than those
presented by this Orchis, it may be worth while
briefly to sum them up. As the flowers are visited
both by day and night-flying Lepidoptera, it is not-
fanciful to believe that the bright-purple tint (whether
or not specially developed for this purpose) attracts
the day-fliers, and the strong foxy odour the night-
fliers. The upper sepal and two upper petals form a
hood protecting the anther and stigmatic surfaces
from the weather. The labellum is developed into a
long nectary in order to attract Lepidoptera, and we
shall presently give reasons for suspecting that the
nectar is purposely so lodged that it can be sucked
only slowly (very differently from what occurs in most
other plants), in order to give time for the viscid
matter on the under side of the saddle to set hard
and dry. He who will insert a fine and flexible
bristle into the expanded mouth of the flower between
the sloping ridges on the labellum, will not doubt
that they serve as guides and effectually prevent the
bristle or proboscis from being inserted obliquely into
the nectary. This latter circumstance is of manifest
importance, for, if the proboscis were inserted ob-
liquely, the saddle-formed disc would become attached
obliquely, and after the compounded movement of the
pollinia they would not strike the two lateral stigmatic
surfaces.

Then we have the rostellum partially closing the
mouth of the nectary, like a trap placed in a run for

24 OPHREJE. Chap. L

game ; and the trap so complex and perfect, with its
symmetrical lines of rupture forming the saddle-
shaped disc above, and the lip of the pouch below ;
and, lastly, this lip so easily depressed that the pro-
boscis of a moth can hardly fail to uncover the viscid
disc and adhere to it. But if this fails to occur, the
elastic lip rises and covers again the viscid surface,
so as to keep it damp. The viscid matter within the
rostellum is attached to the saddle-shaped disc alone,
and is surrounded by fluid, so that it does not set hard
till the disc is withdrawn. The upper surface of the
saddle, with the attached caudicles, is also kept
damp by the bases of the anther-cells, until it is
withdrawn, and then the curious clasping movement
instantly commences, causing the pollinia to diverge,
followed by the movement of depression, which move-
ments together are exactly fitted to cause the end3
of the two pollen-masses to strike the two stigmatic
surfaces. These stigmatic surfaces are not so sticky
as to tear off the whole pollinium from the proboscis
of the moth, but by rupturing the elastic threads to
secure a few packets of pollen, leaving plenty for other
flowers.*

But let it be observed that, although the moth pro-
bably takes a considerable time to suck the nectar of
a flower, yet the movement of depression in the pol-
linia does not commence (as I know by trial) until
they are fully withdrawn ; nor will the movement be
completed, and the pollinia properly placed for strik-
ing the stigmatic surfaces, until about half a minute
has elapsed, which will give ample time for the moth to

* The late Prof. Trevirarms has but points out two unimportant
confirmed (' Botanische Zeitung,' inaccuracies in the drawing which
1863, p. 241) all my observations, I have given.

Chap. I ORCHIS USTULATA. 25

fly to another plant, and thus effect a union between
two distinct individuals.

Orchis ustulata * resembles 0. pi/ramidalis in some
important respects, and differs from it in others. The
labellum is deeply channelled, and the channel which
replaces the guiding ridges of 0. pyramidalis leads to
the small triangular orifice of the short nectary. The
upper angle of the triangle is overhung by the ros-
tellum, the pouch of which is rather pointed below.
In accordance with this position of the rostellum,
close to the mouth of the nectary, the stigma is
double and lateral. This species shows in an interest-
ing manner how easily two distinct stigmas, like those
of 0. pyramidalis, might be converted into a single
one, by becoming at first slightly lobed like that of
0. mascula, and then acquiring its present structure.
For directly beneath the rostellum there is a narrow
transverse rim, formed of true stigmatic tissue, which
connects together the two lateral stigmas ; so that
if this rim were widened, the two stigmas would be
converted into a single transverse one. Conversely
a single stigma might thus easily be converted into a
double one. The pollinia undergo the usual move-
ment of depression, and in acquiring this position
the two diverge slightly, so as to be ready to strike the
two lateral stigmas.

Orchis (sub-genus Himantoglossum) hircina. — A fine
specimen of this extremely rare British plant, the
Lizard Orchis, with its curious elongated labellum,
was sent me by Mr. Oxenden. The two pollinia
arise from a single almost square disc ; and when

* I am greatly indebted to Mr. kindness in supplying me with
G. Chichester Oxenden of Broome living plants, and information re-
Park for fresh specimens of this garding many of the rarer British
Orchis, and for his never-tiring Orchids.

26 OPHKE.E. Chap. I

they are removed from their cells, they do not di-
verge, but become depressed, sweeping through an
angle of ninety degrees, in about thirty seconds. They
are then in a proper position for striking the single
large stigma which lies beneath the rostellum. In the
case of 0. pyramidalis we have seen that the depression
of the two pollinia is effected by the contraction of
the disc in front of each, two furrows or valleys being
there formed ; whilst with the present species, the
whole front of the disc contracts or sinks down, the
front part being thus separated from the hinder part
by an abrupt step.

Acer as* (Orchis) anthropophora. — The caudicles of
the pollinia are unusually short ; the nectary consists
of two minute rounded depressions in the labellum ;
the stigma is transversely elongated; and lastly the
two viscid discs lie so close together within the ros-
tellum that they affect each other's outline. This
latter fact is worth notice, as a step towards the two
becoming absolutely confluent, as in the following
species of Aceras, in 0. pyramidalis and hircina.
Nevertheless, in Aceras a single pollinium is some-
times removed by insects, though more rarely than
with the other species of Orchis.

Aceras (Orchis) longibracteata. — Mr. Moggridge has
given an interesting account, together with a figure,
of this plant which grows in the South of France.!
The pollinia are attached to a single viscid disc.
When they are removed they do not diverge as in
0. pjramidalis, but converge and then undergo the

* The separation of this genus occurrence of numerous hybrids,

is evidently artificial. It is a true naturally produced, between this

Orchis, but with a very short Aceras and Orchis galeata.

nectary. Dr. Weddell has de- t ' Journ. Linn. Soc. Bot.'

scribed (' Annales des Sc. Nat.,' vol. viii. 1865, p. 256. He gives

3 ser. Bot. torn, xviii. p. 6) the also a figure of Orchis hircina.

Chap. I. NIGEITELLA ANGUSTIFOLIA. 27

movement of depression. The most remarkable point
about this species is that insects seem to suck nectar
out of minute open cells in the honeycombed surface
of the labellum. The flowers are visited by various
hymenopterous and dipterous insects ; and the author
saw the pollinia attached to the forehead of a large
bee, the Xylocojpa violacea.

Neotinea {Orchis) intacta. — Mr. Moggridge sent me
from North Italy living specimens of this very rare
British plant, which, as he informed me, is remark-
able from producing seeds without the aid of insects.
When insects were carefully excluded by me, almost
all the flowers produced capsules. Their fertilisation
follows from the pollen being extremely incoherent, so
as to fall spontaneously on the stigma. Nevertheless
a short nectary is present, the pollinia possess small
viscid discs, and all the parts are so arranged that,
if insects were to visit the flowers, the pollen-masses
would almost certainly be removed and carried to
another flower, but not so effectually as with most
other orchids.

Serapias cordigera, an inhabitant of the South of
France, has been described by Mr. Moggridge in the
paper just referred to. The pollinia are attached to
a single viscid disc ; when first withdrawn, they are
bent backwards, but soon afterwards move forwards
and downwards in the usual manner. As the stigmatic
cavity is narrow, the pollinia are guided into it by two
guiding plates.

Nigritella angustifolia. — This Alpine species is said
by Dr. H. Miiller * to differ from all ordinary orchids
in the ovarium not being twisted ; so that the labellum
stands on the upper side of the flower, and insects

* * Nature,' Dec. 31, 1874, p. 169.

28 OPHRE.E. Chap. I.

alight on the opposite sepals and petals. As a con-
sequence of this, when a butterfly inserts its proboscis
into the narrow entrance of the nectary, the viscid discs
become attached to the lower surface of the proboscis,
and the pollinia afterwards move upwards, instead of
as in all other orchids downwards. They are then in
the proper position for striking the stigma of the next
flower which is visited. Dr. Miiller remarks that the
flowers are frequented by an extraordinary number of
butterflies.

I have now described the structure of most of the
British and of a few foreign species in the genus
Orchis and its close allies. All these species, with the
exception of the Neotinea, require the aid of insects for
their fertilisation. This is obvious from the fact that
the pollinia are so closely embedded in the anther-cells,
and the ball of viscid matter in the pouch-formed
rostellum, that they cannot be shaken out by violence.
We have also seen that the pollinia do not assume the
proper position for striking the stigmatie surface until
some time has elapsed; and this indicates that they
are adapted to fertilise, not their own flowers, but those
on a distinct plant. To prove that insects are neces-
sary for the fertilisation of the flowers, I covered up
a plant of Orchis morio under a bell-glass, before
any of its pollinia had been removed, leaving three
adjoining plants uncovered ; 1 looked at the latter
every morning, and daily found some of the pollinia
removed, till all were gone with the exception of those
in a single flower low down on one spike, and of those
in one or two flowers on the summits of all the spikes,
which were never removed. But it should be observed
that when only a very few flowers remain open on the
summits of the spikes, these are no longer conspicuous,

Chap. I. FERTILISED BY INSECTS. 29

and would consequently be rarely visited by insects.
I then looked at the perfectly healthy plant under
the bell-glass, and it had, of course, all its pollinia in
the anther-cells. I tried an analogous experiment with
specimens of 0. mascula with the same result. It de-
serves notice that the spikes which had been covered
up, when subsequently left uncovered, never had their
pollinia carried away by insects, and did not, of course,
set any seed, whereas the adjoining plants produced
plenty of seed. From this fact it may be inferred
that there is a proper season for each kind of Orchis,
and that insects cease their visits after the proper
season has passed.

With many of the hitherto mentioned species, and
with several other European kinds, the sterility of the
flowers, when protected from the access of insects,
depends solely on the pollen-masses not coming into
contact with the stigma. This has been proved to be
the case by Dr. Hermann Miiller, who, as he informs
me, applied the pollen-masses of Orchis pyramidalis
(44), fusca (6), militaris (14), variegata (3), coriojphora
(6), morio (4), maculata (18), mascula (6), latifolia (8),
incarnata (3), Ophrys muscifera (8), Gymnadenia conop-
sea (14), albida (8), Herminium monorchis (6), Epipogon
aphyllus (2), Epipactis latifolia (14), palustr is (4), Listera
ovata (5), and Cypripedium calceolus (2), to their own
stigmas, and full-sized capsules, containing seeds in
appearance good, were formed. The numbers placed
after the names of the species show how many flowers
were tried in each case. These facts are remarkable,
because Mr. Scott and Fritz Miiller* have proved

* An abstract of their observa- tication,' chap. xvii. 2nd edit, vol
tions is given in my 'Variation of ii. p. 114.
Animals and Plants under Domes-

-+

30 OPHRE^E. Chap. I.

that various exotic species, both in this country and
in their native homes, invariably fail to yield seed-
capsules, when the flowers are fertilised with their own
pollen.

From the observations already given, and from
what will hereafter be shown with respect to Gym
nadenia, Habenaria, and some other species, it is a
safe generalisation* that species with a short and
not very narrow nectary are fertilised by beesf and
flies; whilst those with a much elongated nectary,
or one having a very narrow entrance, are fertilised
by butterflies or moths, these being provided with
long and thin proboscides. We thus see that the
structure of the flowers of Orchids and that of
the insects which habitually visit them, are corre-
lated in an interesting manner, — a fact which has
been amply proved by Dr. H. Miiller to hold good
with many of the Orchideoe and other kinds of
plants.

With respect to Orchis pyramidalis, which possesses,
as we have seen, an elongated nectary, Mr. Bond was
so kind as to send me a large number of Lepidoptera,
out of which I selected twenty-three species, enumer-
ated in the following list, with the pollinia of this
Orchid, which can easily be recognised, attached to
their proboscides.

* Some remarks to this effect near the Jardin de la Faculte (at

were given in my "Notes on Toulouse?) complained that hi3

the Fertilisation of Orchids," in bees returned from the garden

' Annals and Mag. of Nat. Hist.' with their heads charged with

Sept. 1809, p. 2. yellow bodies, of which they could

t M. Meniere (in 'Bull. Bot. not free themselves. This is good

Soc. de France,' torn. i. 1854, p. evidence how firmly the pollinia

370) says he saw in Dr. Gue'pin's are attached. There is, however,

collection, bees collected at Sau- nothing to show whether the pol-

mur with the pollinia of Orchids linia in these cases belonged to

attached to their heads; and he the genus Orchis or to some other

states that a person who kept bees genus of the family.

Chap. I.

FEETILISED BY INSECTS.

31

Polyommatus alexis.
Lycsena phlaeas.
Arge galathea.
Hesperia sylvanus.

„ linea.
Syrichthus alveolus.
Anthrocera filipendulse.

„ trifolii.*

Lithosia complana.
Leucania lithargyria (two speci-
mens).
Caradrina blanda.

„ a! sines.
Agrotis cataleuca.

Eubolia mensuraria (two speci-
mens).

Hadena dentina.

Heliothis marginata (two speci-
mens).

Xylophasia sublustris ''two speci-
mens).

Euclidia glyphica.

Toxocampa pastinum.

Melanippe rivaria.

Spilodes palealis.
„ cinctalis.

Acontia luctuosa.

A large majority of these moths and butterflies
had two or three pairs of pollinia attached to them,
and invariably to the proboscis. The Acontia had
seven pair (fig. 4), and the Fig. 4.

Caradrina no less than eleven
pair ! The proboscis of this
latter moth presented an ex-
traordinary arborescent ap-
pearance. The saddle-formed
discs, each bearing a pair of
pollinia, adhered to the pro-
boscis, one before the other,

witn perfect Symmetry ; and Head and proboscis of Acontia luc-
.-. . 4 ,, „ , , tuosa with seven pair of pollinia

this IOllOWS irom the moth of 0rchis pyramidulis attached

having always inserted its t0 the Prol>oscis-
proboscis into the nectary in exactly the same manner,
owing to the presence of the guiding plates on the
labellum. The unfortunate Caradrina, with its pro-
boscis thus encumbered, could hardly have reached
the extremity of the nectary, and would soon have

* I am indebted to Mr. Parfitt
for an examination of this moth,
which is mentioned in the ' En-
tomologist's Weekly Intelligencer,'
vol. ii. p. 182, and vol. iii. p. 3,
Oct. 3, 1857. The pollinia were

erroneously thought to belong to
Ophrys apifera. The pollen had
changed from its natural _ green
colour to yellow ; on washing it,
however, and drying it, the green
tint returned.

32 OPHRE.E. Chap. I.

been starved to death. Both these moths must have
sucked many more than the seven and eleven flowers,
of which they bore the trophies, for the earlier at-
tached pollinia had lost much of their pollen, showing
that they had touched many viscid stigmas.

The above list proves that many different species
of Lepidoptera visit the same kind of Orchis. The
Hadena dentina also frequents Habenaria. Probably
all the Orchids provided with elongated nectaries
are visited indifferently by many kinds of moths.
Whether any of the British Orchids are fertilised
exclusively by special insects confined to certain
localities is very doubtful ; but we shall hereafter see
that Ejpipactis latifolia seems to be fertilised by wasps
alone. I have twice observed plants of Gymnadenia
conopsea, which had been transplanted into a garden
many miles from its native home, with nearly all
their pollinia removed. Mr. Marshall of Ely* has
made the same observation on similarly transplanted
specimens of 0. maculata. On the other hand fifteen
plants of Ophrys muscifera had not one pollen-mass
there removed. Mdlaxis paludosa was placed in a
bog about two miles from that in which it naturally
grew ; and it had most of its pollinia immediately
removed.

The list which follows serves to show that insects in
most cases perform the work of fertilisation effectually.
But the list by no means gives a fair idea how effectu-
ally it is done ; for I have often found nearly all the
pollinia removed, but kept an exact record only in
exceptional cases, as may be seen by the appended
remarks. Moreover, in most cases, the pollinia which

* ' Gardener's Chronicle,' 1861, marks of mine on this subject
p. 73. Mr. Marshall's communi- previously published in the ' Gar-
cation was in answer to some re- dener's Chronicle,' 1860, p. 528.

Chap. I.

FERTILISED BY INSECTS.

33

had not been removed were in the upper flowers
beneath the buds, and many of these would probably
have been subsequently carried away. I have often
found an abundance- of pollen on the stigmas of flowers
which had not their own pollinia removed, showing
that they had been visited by insects. In many other
cases the pollinia had been removed, but no pollen had
been as yet left on the stigmas.

":}

Orchis morio. Three small plants
Kent

Orchis morio. Thirty-eight plants. N.^
Kent. These plants were examined
after nearly four weeks of extraordi-
narily cold and wet weather in 1860;
and therefore under the most unfavour-
ahle circumstances

Orchis pyramidalis. Two plants. N.l
Kent and Devonshire. . . ./

Orchis pyramidalis. Six plants from twoj
protected valleys. Devonshire . . /

Orchis pyramidalis. Six plants from a)
much exposed bank. Devonshire . j

Orchis maculata. One plant. Stafford-^
shire. Of the twelve flowers which had
not their pollinia removed, the greater
number were young flowers under the
buds .......

Orchis maculata. One plant. Surrey .

Orchis maculata. Two plants. N. and)
S.Kent /

Orchis latifolia. Nine plants from S.
Kent, sent me by the Rev. B. S. Maiden.
The flowers were all mature

Orchis fusca. Two plants. S. Kent.)
Flowers quite mature, and even withered/

Aceras anthropophora. Four plants. S.\
Kent /

5SB.

1111

§1*1

si. |

•25 s2

22

110

102
57

32

21

28

50

63

* S

£.2

hi

s
i N-s |

a o sa cs u

ft

23

5

17

27

5

6

193

8

66

166

12

7
50

119

54
34

34 OPHRE.E. Chap. I.

In the second lot of 0. rnorio, in the preceding list,
we see the injurious effects of the extraordinary cold
and wet season of 1860 on the visits of insects, and,
consequently, on the fertilisation of this Orchid, very
few seed-capsules having been produced.

I have examined spikes of 0. pyramidalis in which
every single expanded flower had its pollinia removed.
The forty-nine lower flowers of a spike from Folkestone
(sent me by Sir Charles Lyell) actually produced forty-
eight fine seed-capsules ; and of the sixty-nine lower
flowers in three other spikes, seven alone had failed to
produce capsules. These facts show how well moths
and butterflies perform their office of marriage-priests.*

The third lot of 0. pyramidalis in the above list
grew on a steep grassy bank, overhanging the sea near
Torquay, and where there were no bushes or other
shelter for Lepidoptera ; being surprised how few pol-
linia had been removed, though the spikes were old
and very many of the lower flowers withered, I gathered,
for comparison, six other spikes from two bushy and
sheltered valleys, half a mile on each side of the
exposed bank ; these spikes were certainly younger,
and would probably have had several more of their
pollinia removed ; but in their present condition we
see how much more frequently they had been visited by
moths, and consequently fertilised, than those growing
on the much exposed bank. The Bee Ophrys and
0. pyramidalis grow mingled together in many parts
of England ; and they did so here, but the Bee Ophrys,
instead of being, as usual, the rarer species, was here

* In the summer of 1875, which ing fertilised ; and on this occasion
was a very wet one, I gathered six only 119 flowers produced cap-
unusually fine spikes of 0. pyra- sules, 183 having faihd to do so.
midalis. These bore 302 flowers, Six spikes of O. maculata bore 187
excluding fourteen which were still flowers, of which eighty-two pro-
fully expanded and capable of be- duced capsules, 105 having failed.

Chap. I. FERTILISED BY INSECTS. 35

much more abundant than 0. pyramidalis. No one
would readily have suspected that one chief reason of
this difference probably was, that the exposed situation
was unfavourable to Lepidoptera, and therefore to the
seeding of 0. 'pyramidalis ; whereas, as we shall here-
after see, the Bee Ophrys is independent of insects.

Many spikes of 0, latif cilia were examined, because,
being familiar with the usual state of the closely-allied
0. maculata, I was surprised to find in nine nearly
withered spikes (as may be seen in the list) how few
pollinia had been removed. In one instance, however,
0. maculata had been even worse fertilised ; for seven
spikes with 315 flowers, produced only forty-nine seed-
capsules — that is, on an average only seven capsules
on each spike. In this case the plants formed larger
beds than I had ever before seen ; and I imagine that
there were too many flowers for the insects to visit
and fertilise all of them. On some other plants of
0. maculata growing at no great distance, above thirty
capsules had been produced by each spike.

Orchis fusca offers a still more curious case of
imperfect fertilisation. I examined ten fine spikes
from two localities in South Kent, sent to me by Mr.
Oxenden and Mr. Maiden : most of the flowers on these
spikes were partly withered, with the pollen mouldy
even in the uppermost flowers ; we may therefore infer
that no more pollinia would have been removed. I
examined all the flowers only in two spikes, on account
of the trouble from their withered condition, and the
result may be seen in the list, namely, fifty-four
flowers with both pollinia in place, and only eight
with one or both removed. In this Orchid, and in 0,
latifolia, neither of which had been sufficiently visited
by insects, there were more flowers with one pollinium
than with both removed. I casually examined many

36 OPHKE.E. Chap. I.

flowers in the other spikes of 0. fusca, and the propor-
tion of pollinia removed was evidently not greater
than in the two in the list. The ten spikes bore
altogether 358 flowers, and, in accordance with the
few pollinia removed, only eleven capsules had been
formed : five of the ten spikes produced not a single
capsule ; two spikes had only one, and one had as
many as four capsules. As corroborating what I have
before said with respect to pollen being often found on
the stigmas of flowers which retain their own pollinia,
I may add that, of the eleven flowers which had
produced capsules, five had both pollinia still within
their now withered anther-cells.

From these facts the suspicion naturally arises that
0. fusca is so rare a species in Britain from not being
sufficiently attractive to insects, and to its not
producing a sufficiency of seed. C. K. Sprengel*
noticed, that in Germany 0. militaris (ranked by
Bentham as the same species with 0. fusca) is likewise
imperfectly fertilised, but more perfectly than our 0.
fusca ; for he found five old spikes bearing 138 flowers
which had set thirty-one capsules ; and he contrasts the
state of these flowers with those of Gymnadenia conop-
sea, in which almost every flower produces a capsule.

An allied and curious subject remains to be discussed.
The existence of a well-developed spur-like nectary
seems to imply the secretion of nectar. But Sprengel,
a most careful observer, thoroughly searched many
flowers of 0. latifolia and morio, and could never find
a drop of nectar; nor could Kriinitzf find nectar

* 'Das entdeckte Geheimniss,' tung der Nektarien,' 1833, s. 28.

etc. s. 404. See also ' Das entdeckte Geheim-

t Quoted by J. G. Kurr in his niss,' s. 403.
4 Untersuchungen tiber die Bedeu-

Chap. I. SECRETION OF NECTAR. 37

either in the nectary or on the labellum of 0. morio,
fusca, militaris, metadata or latifolia. I have looked
to all our common British species and could find no
trace of nectar; I examined, for instance, eleven
flowers of 0. maculaia, taken from different plants
growing in different districts, and taken from the most
favourable position on each spike, and could not find
under the microscope the smallest bead of nectar.
Sprengel calls these flowers " Scheinsaftblumen," or
sham-nectar-producers ; — he believes that these plants
exist by an organized system of deception, for he well
knew that the visits of insects were indispensable for
their fertilisation. But when we reflect on the incalcul-
able number of plants which have lived during a great
length of time, all requiring that insects should carry
the pollen-masses from flower to flower in each gene-
ration ; and as we further know from the number of the
pollen-masses attached to their proboscides, that the
same insects visit a large number of flowers, we can
hardly believe in so gigantic an imposture. He
who believes in Sprengel's doctrine must rank the
sense or instinctive knowledge of many kinds of
insects, even bees, very low in the scale. To test
the intellect of moths and butterflies I tried the
following little experiment, which ought to have been
tried on a larger scale. I removed a few already-
opened flowers on a spike of 0. pyramidalis, and
then cut off about half the length of the nectaries
of the six next non-expanded flowers. When all the
flowers were nearly withered, I found that thirteen
of the fifteen upper flowers with perfect nectaries
had their pollinia removed, and two alone had their
pollinia still in the anther-cells ; of the six flowers
with their nectaries cut off, three had their pollinia
removed, and three were still in place ; and this in-

38 OPHEE^. Chap. I.

dicates that moths do not go to work in a quite sense-
less manner.*

Nature may be said to have tried this same experi-
ment, but not quite fairly; for Orchis pyramidalis,
as shown by Mr. Bentham,t often produces monstrous
flowers without a nectary, or with a short and imperfect
one. Sir C. Lyell sent me several spikes from Folke-
stone with many flowers in this condition : I found six
without a vestige of a nectary, and their pollinia had
not been removed. In about a dozen other flowers,
having either short nectaries, or with the labellum
imperfect, the guiding ridges being either absent or
developed in excess and rendered foliaceous, the
pollinia in one alone had been removed, and the ova-
rium of another flower was swelling. Yet I found
that the saddle-formed discs in these eighteen flowers
were perfect, and that they readily clasped a needle
when inserted in the proper place. Moths had removed
the pollinia, and had thoroughly fertilised the perfect
flowers on the same spikes ; so that they must have
neglected the monstrous flowers, or, if visiting them,
the derangement in the complex mechanism of the
parts had hindered the removement of the pollinia,
and prevented their fertilisation.

Notwithstanding these several facts I still suspected
that nectar must be secreted by our common Orchids,

* Kurr (' Bedeutung der Nek- the corolla, leaving the nectary, of

tarien,' 1833, p 123) cut off the forty flowers of Orchis morio, and

nectaries of fifteen flowers of these set no capsules; and this

Gymnailenia conopsea, and they case shows that insects are guided

did not produce a single capsule : to the flowers by the corolla,

he also tr ated in the same man- Sixteen flowers of Platan thera

ner fiftt-en flowers of Platnnthera treated in the same manner bore

or Hahenaria hi folia, »nd these only one capsule. Similar experi-

set only five capsules; but then it ments made by him on Gymna-

should be observed that the nee- denia seem to me open to doubt,
taries of both these orchids con- t ' Handbook of the British

tain free nectar. He also cut off Flora,' 1858, p. 501.

Ohap. I. SECRETION OF NECTAR. 39

and I determined to examine 0. morio rigorously. As
soon as many flowers were open, I began to examine
them for twenty-three consecutive days : I looked at
them after hot sunshine, after rain, and at all hours :
I kept the spikes in water, and examined them at
midnight, and early the next morning: I irritated
the nectaries with a bristle, and exposed them to
irritating vapours : I took flowers which had lately had
their pollinia removed by insects, of which fact I had
independent proof on one occasion by finding grains
of some foreign pollen within the nectary ; and 1 took
other flowers, which judging from their position on the
spike, would soon have had their pollinia removed ;
but the nectary was invariably quite dry. After the
publication of the first edition of this work, I one
day saw various kinds of bees visiting repeatedly the
flowers of this same Orchid, so that this was evidently
the proper time to examine their nectaries ; but I failed
to detect under the microscope even the minutest drop
of nectar. So it was with the nectaries of 0. maculata
at a time when I repeatedly saw flies of the genus
Empis keeping their proboscides inserted into them
for a considerable length of time. Orchis pyramidalis
was examined with equal care with the same result,
for the glittering points within the nectary were abso-
lutely dry. We may therefore safely conclude that
the nectaries of the above-named Orchids neither in
this country nor in Germany ever contain nectar.

Whilst examining the nectaries of 0. morio and
maculata, and especially of 0. 'pyramidalis and hircina,
I was surprised at the degree to which the inner and
outer membranes forming the tube or spur were sepa-
rated from each other, — also at the delicate nature of
the inner membrane, which could be penetrated very
easily, — and, lastly, at the quantity of fluid contained

40 OPHKE^. Chap. I.

between the two membranes. So copious is this fluid,
that, after cutting off the extremities of the nectaries
of 0. pyramidalis, and gently squeezing them on glass
under the microscope, such large drops of fluid exuded
from the cut ends, that I concluded that at last I had
found nectaries which contained nectar; but when I care-
fully made, without any pressure, a slit along the upper
surface of other nectaries from the same plants, and
looked into them, their inner surfaces were quite dry.

I then examined the nectaries of Gymnadenia conojpsea
(a plant ranked by some botanists as a true Orchis)
and of Habenaria bifolia, which are always full of nectai
up to one-third or two-thirds of their length. The
inner membrane presented the same structure and was
covered with papillae as in the foregoing species ; but
there was a plain difference in the inner and outer
membranes being closely united, instead of being in
some degree separated from each other and charged
with fluid. I was therefore led to conclude that insects
penetrate the lax inner membrane of the nectaries of
the above-named Orchids, and suck the copious fluid
between the two membranes. This was a bold hypo-
thesis ; for at the time no case was known of insects
penetrating with their delicate proboscides even the
laxest membrane. But I have now heard from Mr.
Trimen, that at the Cape of Good Hope moths and
butterflies do much injury to peaches and plums by
puncturing their unbroken skins. In Queensland,
Australia, a moth, the Ojphideres fullonica, bores
through the thick rind of the orange with its wonder-
ful proboscis, provided with formidable teeth.* There
is therefore not the least difficulty in believing that
Lepidoptera with their delicate proboscides, and bees

* My son Francis has described ' Q. Journal of Microscopical
and figured this organ in the Science,' vol. xv. 1875, p. 385.

Chap. 1. SECRETION OF NECTAR. 41

with their much stronger ones, could penetrate with ease
the soft inner membrane of the nectaries of the above-
named Orchids. Dr. H. Miiller is also convinced* that
insects puncture the thickened bases of the standard
petals of the Laburnum,t and perhaps tha petals of
some other flowers, so as to obtain the inchi/iod fluid.

The various kinds of bees which I saw vbiting the
flowers of Orchis morio remained for some time with
their proboscides inserted into the dry nectaries, and
I distinctly saw this organ in constant movement. I
observed the same fact with Empis in the case of 0.
maculata ; and on afterwards opening several of the
nectaries, I occasionally detected minute brown specks,
due as I believe to the punctures made some time
before by these flies. Dr. H. Miiller, who hu*& often
watched bees at work on several species of Chchis, the
nectaries of which do not contain any free nectar, fully
accepts my view. J On the other hand, Delpino still
maintains that Sprengel is right, and that insects are
continually deceived by the presence of a nectary,
though this contains no nectar. § His belief is founded
chiefly on a statement by Sprengel that insects soon
find out that it is of no use to visit the nectaries of
these orchids, as shown by their fertilising only the

* ' Die Befruchtung,' &c. p. 235. tinct case, namely, the presence
t Treviranns confirms (' Bot. of nectar in several monocotyle-
Zeitung,' 1863, p. 10) a statement donous plants (as described by
made by Salisbury, that when the Ad. Brongniart in ' Bull. Soc. Bot.
filaments in the flowers of another de France,' torn. i. 1854, p. 75)
leguminous plant, Edwardsia, fall between the two walls <Nfeuillets)
oft", or when they aie cautiously which form the divisions of the
separated, a large quantity of ovarium. But the nectar in this
sweet fluid flows from the points case is conducted to the outside
of separation ; and as beforehand by a channel ; and the secreting
there was no trace of any such surface is homologically an ex-
fluid, it must have been contained, terior surface.
as Treviranns remarks, within the J 4Die Befruchtung,' &c. p. 84.
cellular tissue. I may add an ap- § ' Ult. Osservazioni sulla Di-
parently similar, but really dis- cogamia,' 1875, p. 121.

42 OPHRL^J. Chap. I.

lower and first opened flowers. But this statement is
completely contradicted by my observations previously
given, from which it follows that very many of the
upper flowers are fertilised ; for instance, on a spike
of 0. pyramidalis with between fifty and sixty flowers,
no less than forty-eight had their pollinia removed.
Nevertheless, as soon as I learnt that Delpino still be-
lieved in Sprengel's view, I selected during the un-
favourable season of 1875 six old spikes of 0. maculata,
and divided each into halves, so as to observe whether
many more capsules were produced by the lower than
by the upper half. This certainly was not always the
case ; for in some of the spikes no difference could be
detected between them ; in others there were more cap-
sules in the lower, while in others there were more in
the upper half. A spike of 0. pyramidalis examined
in the same manner produced twice as many capsules
in the upper as in the lower half. Bearing in mind
these facts and others before given, it appears to me
incredible that the same insect should go on visiting
flower after flower of these Orchids, although it never
obtains any nectar. Insects, or at least bees, are by
no means destitute of intelligence. They recognise
from a distance the flowers of the same species, and
keep to them as long as they can. When humble-
bees have bitten holes through the corolla, as they
often do, so as to reach the nectar more easily, hive-
bees immediately perceive what has been done and
take advantage of the perforations. When flowers
having more than a single nectary are visited by many
bees, so that the nectar is exhausted in most of them,
the bees which afterwards visit such flowers insert
their proboscides only into one of the nectaries, and
if they find this exhausted, they instantly pass on to
another flower. Can it be believed that bees which

Chap. I. SECRETION OF NECTAR. 43

show this much intelligence, should persevere in
visiting flower after flower of the above-named Orchids,
and in keeping their proboscides in constant movement
for some time within the nectaries, in the hope of
obtaining nectar which is never present? This, as I
have said, seems to me utterly incredible.

It has been shown how numerous and beautiful are
the contrivances for the fertilisation of Orchids. We
know that it is of the highest importance that the
pollinia, when attached to the head or proboscis of an
insect, should be fixed symmetrically, so as not to fall
either sideways or backwards. We know that in the
species as yet described the viscid matter of the disc
sets hard in a few minutes when exposed to the air,
so that it would be a great advantage to the plant if
insects were delayed in sucking the nectar, time being
thus allowed for the disc to become immovably affixed.
It is manifest that insects must be delayed by having
to bore through several points of the inner membrane
of the nectary, and to suck the nectar from the inter-
cellular spaces ; and we can thus understand why the
nectaries of the above-named species of Orchis do not
contain free nectar, but secrete it internally between
the two membranes.

The following singular relation supports this view
in a striking manner. I have found free nectar within
the nectaries of only five British species of Ophreae,
namely, in G-ymnadenia conopsea and albida, in
Habenaria bifolia and chlorantha, and in Peristylus (or
Habenaria) viridis. The first four of these species have
the viscid surfaces of the discs of their pollinia naked
or not enclosed within pouches, and the viscid matter
does not rapidly set hard when exposed to the air, as if
it did, it would immediately have been rendered use-
less: and this shows that it must differ in chemical

44 OPHRE^. Chap. I

nature from that in the foregoing species of Orchis.
But to make sure of this fact I removed the pollinia
from their anther-cells, so that the upper as well as the
under surfaces of the viscid discs were freely exposed
to the air ; in Gymnadenia conopsea the disc remained
sticky for two hours, and in Hahenaria chlorantha for
more than twenty-four hours. In Peristylus viridis the
viscid disc is covered by a pouch-formed membrane,
but this is so minute that botanists have overlooked
it. I did not, when examining this species, see the
importance of ascertaining exactly how soon the
viscid matter set hard ; but I copy from my notes
the words written at the time : " disc remains sticky
for some time when removed from its little pouch."

Now the meaning of these facts is clear : as the
viscid matter of the discs of these five latter species is
so adhesive that it serves to attach the pollinia firmly
to the insects which visit the flowers, without setting
hard, there would be no use in the insects being
delayed by having to bore holes at several points
through the inner membrane of the nectaries ; and in
these five species, and in these alone, we find copious
nectar ready stored for rapid suction in open nectaries.
On the other hand, whenever the viscid matter sets
hard by exposure for a short time to the air, it would
manifestly be advantageous to the plant, if insects
were delayed in obtaining the nectar ; and in all such
species the nectar is lodged within intercellular spaces,
so that it can be obtained only by the inner mem-
brane being penetrated at several points, and this will
require time. If this double relation is accidental,
it is a fortunate accident for the plants ; but I cannot
believe it to be so, and it appears to me one of the
most wonderful cases of adaptation which has ever
been recorded.

Chap.IL ophrys muscifeea. 45

CHAPTER II.

ophre^e — continued.

Fly and Spider Ophrys — Bee Ophrys, apparently adapted for perpetual
self-fertilisation, but with paradoxical contrivances for intercrossing
— Herminium monorchis, attachment of the pollinia to the front legs
of insects — Peristylus viridis, fertilisation indirectly effected by nectar
secreted from three parts of the labellum— Gymnadenia conopsea,
and other species — Habenaria or Platanthera chlorantha and
bifolia, their pullinia attached to the eyes of Lepidoptera — Other
species of Habenaria — Bonatea — Disa— Summary on the powers of
movement in the pollinia.

The genus Ophrys differs from Orchis chiefly in
having separate pouch-formed rostella,* instead of
the two being confluent.

In Ophrys muscifera, or the Fly Ophrys, the chief
peculiarity is that the caudicle of the pollinium
(B, fig. 5) is doubly bent. The nearly circular piece
of membrane, to the under side of which the ball of
viscid matter adheres, is of considerable size, and forms
the summit of the rostellum. It is thus freely exposed

* It is not correct to speak of fold of membrane (see B in fig. 1)

two roatella, but the inaccuracy projecting between the bases of

may be forgiven from its conve- the anther-cells. This folded

nience. The rostellum strictly is crest (sometimes converted into a

a single organ, formed by the solid ridge) corresponds with the

modification of the dorsal stigma smooth surface lying between the

and pistil ; so that in < iphrys the two pouches in Ophrys, and owes

two pouches, the two viscid discs, its protuberant and folded condi-

and the space between them to- tion in Orchis to the two pouches

gether form the true rostellum. having been brought together and

Again, in Orchis I have spoken of rendered confluent. This modi-

the pouch-formed organ as the fication will be more fully ex-

rostellum, but strictly the rostel- plained in a future chapter,
lum includes the little crest or

16

OPHKE^E.

Chap. IL

to the air, instead of lying almost hidden at the base of
the anther, as in Orchis, and thus kept damp. Never-
theless, when a pollinium is removed, the caudicle
bends downwards in the course of about six minutes,
and, therefore, at an unusually , slow rate; the upper

Fig. 5.

Ophrys muscifera, or Fly Ophrys.

a. anther. s. stigma.

r,r. rostella. I. labellum.

A. Flower viewed in front : the two
upper petals are almost cylin-
drical and hairy : the two ros-
tella stand a little in advance

of the bases of the anther-cells ;
but this is not shown from the
foreshortening of the drawing.
One of the two pollinia removed
from its anther-cell, and viewed
laterally.

end still remaining curved. I formerly thought that
it was incapable of any movement, but have been con-
vinced by Mr. T. H. Farrer of my error. The ball of
viscid matter is bathed in fluid within the pouch formed
by the lower half of the rostellum, and this is necessary,

Chap. II. OPHRYS MUSCIFERA. 47

as the viscid matter quickly sets hard when exposed to
the air. The pouch is not elastic, and does not spring
up when the pollinium is removed. Such elasticity
would have been useless, as there is here a separate
pouch for each viscid disc ; whereas in Orchis, after
one pollinium has been removed, the other has to
be kept covered up and ready for action. Hence it
appears that nature had been so economical as to save
even superfluous elasticity.

The pollinia cannot, as I have often proved, be shaken
out of the anther-cells. That insects of some kind
visit the flowers, though not frequently, and remove
the pollinia, is certain, as we shall immediately see.
Twice I have found abundant pollen on the stigmas of
flowers, in which both pollinia were still in their cells ;
and no doubt this might have been much oftener ob-
served. The elongated labellum affords a good landing-
place for insects : at its base, just beneath the stigma,
there is a rather deep depression, representing the
nectary in Orchis ; but I could never see a trace of
nectar within it ; nor have I ever observed any insects
approach these inconspicuous and scentless flowers, often
as I have watched them. There is, however, on each side
of the base of the labellum a small shining projection,
having an almost metallic lustre, which appears curi-
ously like a drop of fluid or nectar ; and as these flowers
are only visited occasionally by insects, Sprengel's view
of the existence of sham-nectaries is far more probable
in this case than in any other known to me. On
several occasions I have detected minute punctures in
these protuberances, but I was not able to decide whether
they had been made by insects, or whether superficial
cells had spontaneously burst. Similar shining pro-
tuberances are present on the labella of all the other
species of Ophrys. The two rostella stand not far

48

OPHITES.

Chap. II.

apart, and project over the stigma ; and if any object
is gently pushed against one of them, the pouch is
depressed and the viscid ball together with the pol-
linium adheres to it and is easily removed.

The structure of the flower leads me to believe that
small insects (as we shall see in the case of Listera)
crawl up the labellum to its base, and that in bending
their heads downwards, so as to puncture and suck, or
only to examine one of the small shining protuberances,
they push against the pouch, and a pollinium is attached
to their heads ; they then fly to another flower, and
there bending down in a similar manner, the attached
and doubly-bent pollinium, after the movement of
depression, strikes the sticky stigmatic surface, and
leaves pollen on it. Under the next species we shall
see reason for believing that the natural double cur-
vature of the caudicle compensates for its slight power
of movement, compared with that in all the species of
Orchis.

In 1858, 17 plants, bearing 57 flowers,)
growing near each other were examined/

In 1858, 25 plants growing in another)
spot, and bearing 65 flowers . . J

In 1860, 17 plants, bearing 61 flowers

In 1861, 4 plants from S. Kent, bearing 24)
flowers (all the previous plants having >
grown in N. Kent) . . . . j

Total

Number of Flowers.

Both Pollinia

or one removed

by Insects.

Both Poll'nia
in their Cells.

30

15

28

15

27

50
33

9

88

119

That insects visit the flowers of the Fly Ophrys
and remove the pollinia, though not effectually or suffi-

Chap. II. OPHRYS MUSCIFERA. 49

ciently, the following cases show. During several
years before 1858 I occasionally examined some flowers,
and found that only thirteen out of 102 had one or
both pollinia removed. Although at the time I re-
corded in my notes that most of the flowers were
partly withered, I now think that I must have included
many young flowers, which might perhaps have been
subsequently visited ; so I prefer trusting to the fol-
lowing observations.

We here see that, out of 207 flowers examined, not
half had been visited by insects. Of the eighty-eight
flowers visited, thirty-one had only one pollinium re-
moved. As the visits of insects are indispensable for
the fertilisation of this Orchid, it is surprising (as in
the case of Orchis fusca) that the flowers have not been
rendered more attractive to insects. The number of
seed-capsules produced is proportionably even less than
the number of flowers visited by insects. The year
1861 was extraordinarily favourable to this species in
this part of Kent, and I never saw such numbers
in flower ; accordingly I marked eleven plants, which
bore forty-nine flowers, but these produced only seven
capsules. Two of the plants each bore two capsules,
and three other plants each bore one, so that no less
than six plants did not produce a single capsule !
What are we to conclude from these facts ? Are the
conditions of life unfavourable to this species, though
during the year just alluded to it was so numerous in
some places as to deserve to be called quite common ?
Could the plant nourish more seed ; and would it be of
any advantage to it to produce more seed ? Why does
it produce so many flowers, if it already produces a
sufficiency of seeds ? Something seems to be out of
order in its mechanism or in its conditions. We shall
presently see that Ophrys apifera or the Bee Ophrys

50

OPHEE^E. Chap. II.

presents a wonderful contrast in every flower producing
a capsule.

Ophrys aranifera, or the Spider Ophrys. — I am in-
debted to Mr. Oxenden for some spikes of this rare
Fig. 6. species. Whilst the pollinia

remain enclosed within their
cells, the lower part of the cau-
dicle projects up in a straight
line from the viscid disc, and
therefore has a very different
T TT" f°rm from the corresponding

Ophrys aranifera. part of the Caildicle of 0. mUS-

A. Poliinium before the act of cifera ; but the upper part (A,

B. Poliinium Tfter' the act of fig- 6) is a little bent forward,

depression. that is, towards the labellum.

The point of attachment of the caudicle to the disc
is hidden within the bases of the anther- cells, and
is thus kept damp ; consequently, as soon as the
pollinia are exposed to the air, the usual movement of
depression takes place, and they sweep through an
angle of about ninety degrees. By this movement
they assume, supposing them to be attached to an
insect's head, a position exactly adapted for striking
the stigmatic surface, which is situated, relatively to
the pouch-formed rostella, rather lower down in the
flower than in the Fly Ophrys.

I examined fourteen flowers of the Spider Ophrys,
several of which were partly withered; and in none
were both pollinia, and in three alone was one poliinium
removed. Hence this species, like the Fly Ophrys,
is but little visited by insects in England. In parts
of Italy it is even less visited, for Delpino states*
that in Liguria hardly one flower out of 3000 sets a

Ult. Oeserv. s. Dicogamia,' &c. Parte i. 1868-69, p. 177.

Chap. II. OPHKYS AKACHNITES. 51

capsule, though near Florence rather more capsules
are produced. The labellum does not secrete any
nectar. The flowers, however, must be occasionally-
visited and fertilised by insects, for Delpino found*
pollen-masses on the stigmas of some flowers which
still retained both their own pollinia.

The anther-cells are remarkably open, so that with
some plants which were sent me in a box, two pair
of pollinia fell out, and stuck by their viscid discs
to the petals. Here we have an instance of the first
appearance of a trifling structure which is of not the
least use to its possessor, but becomes when a little
more developed, highly beneficial to a closely-allied
species ; for although the open state of the anther-cells
is useless to the Spider Ophrys, it is of the highest
importance, as we shall presently see, to the Bee
Ophrys. The flexure of the upper end of the caudicle
of the pollinium is of service to the Spider and Fly
Ophrys, by aiding the pollen-masses, when carried by
insects to another flower, to strike the stigma ; but by
an increase of this bend together with increased flexi-
bility in the Bee Ophrys, the pollinia become adapted
for the widely different purpose of self-fertilisation.

Ophrys arachnites. — This form, of which Mr. Oxenden
sent me several living specimens, is fjU 7#
considered by some botanists as only a
variety of the Bee Ophrys, by others as a
distinct species. The anther-cells do not
stand so high above the stigma, and do
not overhang it so much, as in the Bee
Ophrys, and the pollen masses are more p0ihnium of
elongated. The caudicle is only two- Ophrys ar achniu
thirds, or even only half as long as that of the Bee

' Fecondazione nelle Piante Antocarpee/ 1867, p. 20.

52 OPHKE.ZE. Chap. II.

Ophrys, and is much more rigid; the upper part is
naturally curved forward; the lower part undergoes
the usual movement of depression, when the pollinia
are removed from their cells. The pollen-masses
never fall spontaneously out of their cells. This plant,
therefore, differs in every important respect from 0.
apifera, and seems to be much more closely allied to
0. aranifera.

Ophrys scolopax of Cavanilles. — This form inhabits
the north of Italy and the south of France. Mr.
Moggridge says* that at Mentone it never shows any
tendency to fertilise itself, whilst at Cannes the pollen-
masses naturally fall out of their cells and strike the
stigma. He adds : " This material difference between
the two is accomplished by a very slight bend in the
anther-cells, which are prolonged into a beak of variable
length, in the case of the self-fertilising blossoms."

Ophrys apifera. — The Bee Ophrys differs widely
from the great majority of Orchids in being excellently
constructed for fertilising itself. The two pouch -formed
rostella, the viscid discs, and the position of the stigma,
are nearly the same as in tLe other species of Ophrys ;
but the distance of the two pouches from each other,
and the shape of the pollen-masses are somewhat
variable.f The caudicles of the pollinia are remark-
ably long, thin, and flexible, instead of being, as
in all the other Ophrese seen by me, rigid enough
to stand upright. They are necessarily curved
forward at their upper ends, owing to the shape of
the anther-cells ; and the pear-shaped pollen-masses
lie embedded high above and directly over the

* ' Journ. Linn. Soc' vol. viii. symmetrically confluent as in the

1865, p. 258. genus Orchis, and with the two

f I once found a single flower viscid discs likewise confluent, as

on the summit of a spike, with in Orchis pyramidalis or hircina.
the two rostella as completely and

Chap. II.

OPHRYS APIFERA.

53

stigma. The anther-cells naturally open soon after
the flower is fully expanded, and the thick ends of
the pollen-masses then fall out, the viscid discs still
remaining in their pouches. Slight as is the weight
of the pollen-masses, yet the caudicles are so thin and
quickly become so flexible, that in the course of a few
hours they sink down, until they hang freely in the air

Fig. 8.

OPHRTS APIFERA, OR BEE OPHRYS.

a. anther.

■. /. label lum.

A. Side view of flower, with the
upper sepal and the two upper
petals removed. One polliuium,
with its disc still in its pouch,
is represented as just falling

out of the anther-cell.; and
the other has fallen almost to
its full extent, opposite to the
hidden stigmatic surface.
B. Pollinium in the position in
which it lies embedded.

(see lower pollen-mass in fig. A) exactly opposite to
and in front of the stigmatic surface. In this position
a breath of air, acting on the expanded petals, sets
the flexible and elastic caudicles vibrating, and they
almost immediately strike the viscid stigma, and,
being there secured, impregnation is effected. To
make sure that no other aid was requisite, though

.54 OPHEE^]. Chap. II

the experiment was superfluous, I covered up a plant
under a net, so that the wind, but no insects, could
pass in, and in a few days the pollinia became attached
to the stigmas. But the pollinia of a spike kept in
water in a still room remained free, suspended in front
of the stigma, until the flowers withered.

Kobert Brown first observed that the structure of the
Bee Ophrys is adapted for self-fertilisation.* When
we consider the unusual and perfectly-adapted length,
as well as the remarkable flexibility of the caudicles ;
when we see that the anther-cells naturally open, and
that the masses of pollen, from their weight, slowly
fall down to the exact level of the stigmatic surface,
and are there made to vibrate by the slightest breath
of wind until the stigma is struck ; it is impossible
to doubt that these several points of structure and
function, which occur in no other British Orchid, are
specially adapted for self- fertilisation.

The result is what might have been anticipated. 1
have often noticed that the spikes of the Bee Ophrys
apparently produced as many seed-capsules as flowers ;
and near Torquay I carefully examined many dozen
plants, some time after the flowering season ; and on
all I found from one to four, and occasionally five,
fine capsules, that is, as many capsules as there had
been flowers. In extremely few cases, with the excep-
tion of a few deformities, generally on the summit of
the spike, could a flower be found which had not pro-
duced a capsule. Let it be observed what a contrast
this species presents with the Fly Ophrys, which
requires insect aid for its fertilisation, and which from
forty-nine flowers produced only seven capsules!

* « Trnnsact. Linn. Soc' vol. common to the genus. As far as
xvi. p. 740. Brown erroneously the four British species are con-
believed that this peculiarity was cerned, it applies to this one alone.

Chap. II. OPHRYS APIFEEA. 55

From what I had then seen of other Orchids, I
was so much surprised at the self-fertilisation of this
species, that I examined during many years, and asked
others to examine, the state of the pollen-masses in
many hundreds of flowers, collected in various parts of
England. The particulars are not worth detailing;
but I may give as an instance, that Mr. Farrer
found in Surrey that not one flower out of 106
had lost both pollinia, and that only three had lost
a single one. In the Isle of Wight, Mr. More
examined 136 flowers, and of these the very unusual
number of ten had lost both, and fourteen had lost
one ; but then he found that in eleven cases the
caudicles had been gnawed through apparently by
snails, the discs still remaining in their pouches ; so
that the pollinia had not been carried away by insects.
In some few cases, also, in which I found the pollinia
removed, the petals were marked with the slime of
snails. Nor must we forget that a blow from a
passing animal, and possibly heavy storms of wind
might occasionally cause the loss of one or both
pollinia.

During most years the pollen-masses of the many
hundred flowers which were examined, adhered with
the rarest exceptions to the stigma, with their discs still
enclosed within the pouches. But in the year 1868,
from some cause the nature of which I cannot conjecture,
out of 116 flowers gathered in two localities in Kent,
seventy -five retained both pollinia in their cells ; ten
had one pollinium, and only thirty-one had both
adhering to the stigma. Long and often as I have
watched plants of the Bee Ophrys, I have never seen
one visited by any insect.* Bobert Brown imagined

* Mr. Gerard E. Smith, in his 'Catalogue of Plants of S. Kent,

56 OPHEEJB. Chap. II.

that the flowers resembled bees in order to deter their
visits, but this seems extremely improbable. The
flowers with their pink sepals do not resemble any-
British bee, and it is probably true, as I have heard it
said, that the plant received its name merely from the
hairy labellum being somewhat like the abdomen of a
humble-bee. We see how fanciful many of the names
are, — one species being called the Lizard and another
the Frog Orchis. The resemblance of 0. muscifera to
a fly is very much closer than that of 0. apifera to a
bee ; and yet the fertilisation of the former absolutely
depends on and is effected by the means of insects.

All the foregoing observations relate to England,
but Mr. Moggridge made similar ones on the Bee
Ophrys in Northern Italy and Southern France, as did
Treviranus* in Germany, and Dr. Hooker in Morocco.
We may therefore conclude, — from the pollinia spon-
taneously falling on the stigma — from the co-related
structure of all the parts for this purpose — and from
almost all the flowers producing seed-capsules — that
this plant has been specially adapted for self-fertilisa-
tion. But there is another side to the case.

When an object is pushed against one of the
pouches of the rostellum, the lip is depressed, and the
large viscid disc adheres firmly to it ; and when the
object is removed, so is the pollinium, but perhaps
not quite so readily as in the other species of
Ophrys. Even after the pollen-masses have naturally
fallen out of their cells on to the stigma, their removal
can sometimes be thus effected. As soon as the disc is

1829, p. 25, says: "Mr. Price cannot conjecture,

has frequently witnessed attacks * ' Bot. Zeitung,' 1863, p. 241.

made upon the Bee Orchis by a This botanist at first doubted my

bee, similar to those of the observations on Ophrys apifera

troublesome Apis muscorum." and aranifera, but has since fully

What this sentence means I confirmed them.

Chap. IL OPHRYS APIFERA. 57

drawn out of its pouch a movement of depression
commences, by which the pollinium if attached to
the front of an insect's head would be brought into
a proper position for striking the stigma. When a
pollen-mass is placed on the stigma and then with-
drawn, the elastic threads by which the packets are
tied together break, and leave several packets on the
viscid surface. In all other Orchids the meaning of
these several contrivances is unmistakably clear —
namely, the downward movement of the lip of the ros-
tellum when gently pushed — the viscidity of the disc
— the depression of the caudicle as soon as the disc
is exposed to the air — the rupturing of the elastic
threads — and the conspicuousness of the flower. Are
we to believe that these adaptations for cross-fertilisa-
tion in the Bee Ophrys are absolutely purposeless, as
would certainly be the case if this species has always
been and will always be self-fertilised ? It is, however,
just possible that insects, although they have never
been seen to visit the flowers, may at rare intervals
transport the pollinia from plant to plant, during such
seasons as that of 1868, when the pollinia did not all
fall out of the anther- cells so as to reach the stigmas.
The whole case is perplexing in an unparalleled degree,
for we have in the same flower elaborate contrivances
for directly opposed objects.

That cross-fertilisation is beneficial to most Orchids,
we may infer from the innumerable structures serving
for this purpose which they present ; and I have
elsewhere shown in the case of many other groups of
plants * that the benefits thus derived are of high
importance. On the other hand, self-fertilisation is
manifestly advantageous in as far as it ensures a full

* ' The Effects of Cross and Self-Fertilisation in the Vegetable
Kingdom,' 1876.

4

58 OPHRE^. Chap. IL

supply of seed; and we have seen with the other
British species of Ophrys which cannot fertilise them-
selves, how small a proportion of their flowers produce
capsules. Judging therefore from the structure of
the flowers of 0. apifera, it seems almost certain that
at some former period they were adapted for cross-
fertilisation, but that failing to produce a sufficiency
of seed they became slightly modified so as to fertilise
themselves. It is, however, remarkable on this view,
that none of the parts in question show any tendency
to abortion — that in the several and distant countries
which the plant inhabits, the flowers are still con-
spicuous, the discs still viscid, and the caudicles still
retain the power of movement when the discs are ex-
posed to the air. The metallic points at the base of
the labellum are however smaller than in the other
species ; and if these serve to attract insects, this dif-
ference is of some signification. As it can hardly be
doubted that 0. apifera was at first constructed so as
to be regularly cross-fertilised, it may be asked will it
ever revert to its former state ; and if it does not so
revert, will it become extinct ? These questions cannot
be answered, any more than in the case of those plants
which are now propagated exclusively by buds, stolons,
&c, but which produce flowers that rarely or never set-
any seed ; and there is reason to believe that a sexual
propagation is closely analogous to long-continued
self- fertilisation.

Finally Mr. Moggridge has shown that in North
Italy Ophrys apifera, aranifera, arachnites, and seolopax
are connected by so many and such close intermediate
links,* that all seem to form a single species in

* These forms are illustrated by ' Verhandlungen der Kaiserl.

beautiful coloured drawings in Leop. Car. Akad.' (Nov. Act.),

the 'Flora of Mentone,' pi. 43 to torn. xxxv. 1869
45; and in his memoir in the

Chap. II. HEKMINIUM MONOKCHIS. 59

accordance with the belief of Linnaeus, who grouped
them all together under the name of Ophrys insectifera.
Mr. Moggridge further shows that in Italy 0. aranifera
flowers first, and 0. apt/era last, the intermediate
forms at intermediate periods; and according to Mr.
Oxenden, the same fact holds good to a certain extent
in Kent. The three forms which inhabit England do
not seem to blend into one another as in Italy, and I
am assured by Mr. Oxenden, who has closely attended
to these plants in their native homes, that 0. aranifera
and apifera always grow in distinct spots. The case
therefore is an interesting one, as here we have forms
which may be and generally have been ranked as true
species, but which in North Italy have not as yet been
fully differentiated. The case is all the more interest-
ing, as the intermediate forms can hardly be due to
the crossing of 0. aranifera with apiftra ; this latter
species being regularly self-fertilised and apparently
never visited by insects. Whether we rank the several
forms of Ophrys as closely allied species or as mere
varieties of the same species, it is remarkable that
they should differ in a character of such physiological
importances as the flowers of some being plainly
adapted for self-fertilisation, whilst the flowers of
others are strictly adapted for cross-fertilisation, being
utterly sterile if not visited by insects.

Herminium monorchis. — The Musk Orchis, which is
a rare British plant, is generally spoken of as having
naked glands or discs, but this is not strictly correct.
The disc is of unusual size, nearly equalling the mass
of pollen-grains : it is subtriangular, with one side pro-
tuberant, and somewhat resembles a distorted helmet
in shape : it is formed of hard tissue with the base
hollowed out, and viscid; the base resting on and
being covered by a narrow strip of membrane, which is

60 OPHRE.E. Chap. II.

easily pushed away, and answers to the pouch in
Orchis. The whole upper part of the helmet answers
to the minute oval bit of membrane to which the
caudicle of Orchis is attached and which in Ophrys
is larger and convex. When the lower part of the
helmet is moved by any pointed object, the point
readily slips into its hollow base, and is there held so
firmly by the viscid matter, that the whole helmet
appears adapted to stick to some prominent part of an
insect's body. The caudicle is short and very elastic ;
it is attached not to the apex of the helmet, but to the
hinder end ; if it had been attached to the apex, the
point of attachment would have been freely exposed to
the air and not kept damp ; and then the pollinium
when removed from its cell would not have been
quickly depressed.

This movement is well marked, and serves to bring
the end of the pollen-mass into a proper position for
striking the stigma. The two viscid discs stand wide
apart. There are two transverse stigmatic surfaces,
meeting by their points in the middle ; but the broad
part of each lies directly beneath each disc. The
labellum is remarkable from not differing much in
shape from the two upper petals, and from not always
occupying the same position in reference to the axis
of the plant, owing to the ovarium being more or less
twisted. This state of the labellum is intelligible, for
as we shall see, it does not serve as a landing-place for
insects. It is upturned, and together with the two
other petals makes the whole flower in some degree
tubular. At its base there is a hollow so deep as
almost to deserve to be called a nectary ; but I could
not perceive any nectar, which, as I believe, remains
enclosed in the intercellular spaces. The flowers are
very small and inconspicuous, but emit a strong honey-

Chap. II. HEEMINIUM MONORCHIS. 61

like odour. They seem highly attractive to insects ; in
a spike with only seven flowers recently open, four had
both pollinia, and one had a single polliniuni removed.
When the first edition of this book appeared I did
not know how the flowers were fertilised, but my son
George has made out the whole process, which is
extremely curious and differs from that in any other
Orchid known to me. He saw various minute insects
entering the flowers, and brought home no less than
twenty-seven specimens with pollinia (generally with
only one, but sometimes with two) attached to them.
These insects consisted of minute Hymenoptera (of
which Tetrastichus diaphantus was the commonest),
of Diptera and Coleoptera, the latter being Malthodes
hrevicollis. The one indispensable point appears to
be that the insect should be of very small size, the
largest being only the T^ of an inch in length. The
pollinia were always attached to the same place,
namely, to the outer surface of the femur of one of the
front legs, and generally to the projection formed by
the articulation of the femur with the coxa. The
cause of this peculiar mode of attachment is suffici-
ently clear : the middle part of the labellum stands so
close to the anther and stigma, that insects always enter
the flower at one corner, between the edge of the
labellum and one of the upper petals ; they also almost
always crawl in with their backs turned directly or
obliquely towards the labellum. My son saw several
which began to crawl into the flowers in a different
position ; but they came out and changed their posi-
tion. Standing in either corner of the flower, with
their backs turned towards the labellum, they insert
their heads and fore legs into the short nectary, which
is seated between the two widely separated viscid discs.
I ascertained that they had occupied this position by

62 OPHRE^J. Chap. II.

finding three dead insects, permanently glued to the
discs. Whilst sucking the nectar, which takes two or
three minutes, the projecting joint of the femur stands
under the large helmet-like viscid disc on either side ;
and when the insect retreats, the disc exactly fits on
and is glued to the prominent joint, or to the surface
of the femur. The movement of depression in the
caudicle now takes place, and the mass of pollen-grains
then projects just beyond the tibia ; so that the insect,
when entering another flower, can hardly fail to ferti-
lise the stigma, which is situated directly beneath the
disc on either side.

Fig. 9.

Peristylus viridis, or Frog Orchis.
Front view of flower.

a. anther.
s. stigma,
n. orifice of central nectary.

nV. lateral nectaries.
/. labellum.

Peristylus viridis. — This plant, which bears the odd
Dame of the Frog Orchis, has been placed by many
botanists in the genus Habenaria or Platan thera; but
as the discs are not naked, it is doubtful whether this

Chap. II. PEEISTYLUS VIKIDIS. 63

classification can be correct. The rostella are small
and widely separated from each other. The viscid
matter on the under side of the disc forms an oval ball
which is enclosed within a small pouch. The upper
membrane to which the caudicle is attached is of large
size relatively to the whole disc, and is freely exposed
to the air. Hence probably it is that the pollinia when
removed from their cases do not become depressed
until, as Mr. T. H. Farrer has observed, twenty or
thirty minutes have elapsed. Owing to this long
interval, I formerly thought that they did not undergo
any movement of depression. Supposing a pollinium
to be attached to the head of an insect, and to have
become depressed, it will stand at the proper angle,
vertically, for striking the stigma. But from the
lateral position of the anther-cells, notwithstanding
that they converge a little towards their upper ends,
it is difficult at first to see how the pollinia when
removed by insects are afterwards placed on the
stigma ; for this is of small size and is situated in the
middle of the flower between the two widely separated
rostella.

The explanation is, I believe, as follows. The base
of the elongated labellum forms a rather deep hollow
in front of the stigma, and in this hollow, but some way
in advance of the stigma, a minute slit-like orifice (n)
leads into a short bilobed nectary. Hence an insect,
in order to suck the nectar with which the nectary is
filled, would have to bend down its head in front of
the stigma. The labellum has a medial ridge, which
would probably induce an insect first to alight on
either side ; but, apparently to make sure of this,
besides the true nectary, there are two spots (riri) which
secrete drops of nectar on each side at the base of
the labellum, bordered by prominent edges, directly

64 OPHEEiE. Chap. II

beneath the two pouches. Now let us suppose an insect
to alight on one side of the labellum so as first to lick
up the exposed drop of nectar on this side ; from the
position of the pouch exactly over the drop, it would
almost certainly get the pollinium of this side attached
to its head. If it were now to go to the mouth of the
true nectary, the pollinium attached to its head from
not having as yet become depressed would not touch
the stigma ; so that there would be no self-fertilisation.
The insect would then probably suck the exposed drop
of nectar on the other side of the labellum, and would
perhaps get another pollinium attached to its head ; it
would thus be considerably delayed by having to visit
the three nectaries. It would then visit other flowers
on the same plant, and afterwards flowers on a distinct
plant ; and by this time, but not before, the pollinia
will have undergone the movement of depression and
will be in a proper position for effecting cross-fertilisa-
tion. It thus appears that the secretion of nectar at
three separate points of the labellum, — the wide dis-
tance apart of the two rostella, — and the slow down-
ward movement of the caudicle without any lateral
movement — are all correlated for the same purpose of
cross-fertilisation.

To what extent this Orchis is frequented by insects,
and what the kinds are, I do not know, but several of
the flowers on two spikes, sent me by the Kev. B. S.
Maiden, had a single pollinium removed, and one
flower had both removed.

We now come to two genera, namely, Gymnadenia
and Habenaria or Platanthera, including four British
species, which have uncovered viscid discs. The viscid
matter, as before remarked, is of a somewhat different
nature from that in Orchis, Ophrys, &c, and does not

Chap. II.

GYMNADENIA CONOPSEA.

65

rapidly set hard. Their nectaries are stored with free
nectar. With respect to the uncovered condition of
the discs, the last species, or Peristylus viridis, is in
an almost intermediate condition. The four following
species compose a much broken series. In Gymna-
denia conopsea the vicid discs are narrow and much
elongated, and lie close together; in G. albida they
are less elongated, but still approximate ; in Habenaria
bifolia they are oval and far apart ; and, lastly, in H.
ehlorantha they are circular and much farther apart.

Gymnadenia conopsea. — In general appearance this
plant resembles pretty closely a true Orchis. The
pollinia differ in having naked, narrow, strap-shaped

Fig. 10.

B

Gymnadenia conopsea.

A. Pollinium, before the act of
depression.

B. Pollinium, after the act of de-
pression, but before it has
closely clasped the disc.

discs, which are as long as the caudicles (fig. 10).
When the pollinia are exposed to the air the caudicle
is depressed in from thirty to sixty seconds ; and as
the posterior surface of the caudicle is slightly hol-
lowed out, it closely clasps the upper membranous
surface of the disc. The mechanism of this movement
will be described in the last chapter. The elastic
threads by which the packets of pollen are bound to-
gether are unusually weak, as is likewise the case with

6Q OPHRE^E. Chap. II

the two following species of Habenaria : this was well
shown by the state of specimens which had been kept
in spirits of wine. This weakness apparently stands in
relation to the viscid matter of the discs not setting
hard and dry as in Orchis; so that a moth with a
pollinium attached to its proboscis might be enabled to
visit several flowers without having the whole polli-
nium dragged off by the first stigma which was struck.
The two strap-shaped discs lie close together, and form
the arched roof of the entrance into the nectary.
They are not protected, as in Orchis, by a lower lip or
pouch, so that the structure of the rostellum is simpler.
When we come to treat of the homologies of the ros-
tellum we shall see that this difference is due to a
small change, namely, to the lower and exterior cells
of the rostellum resolving themselves into viscid
matter ; whereas in Orchis the exterior surface retains
its early cellular or membranous condition.

As the two viscid discs form the roof of the mouth of
the nectary, and are thus brought down near to the
labellum, the two stigmas, instead of being confluent
and standing beneath the rostellum, as in most of
the species of Orchis, are lateral and separate. These
stigmas consist of protuberant, almost horn-shaped,
processes on each side of the nectary. That their
surfaces are really stigmatic I ascertained by finding
them deeply penetrated by a multitude of pollen-
tubes. As in the case of Orchis pyramidalis, it is a
pretty experiment to push a fine bristle straight into
the narrow mouth of the nectary, and to observe how
certainly the narrow elongated viscid discs, forming
the roof, stick to the bristle. When the bristle is
withdrawn, the pollinia adhering to its upper side
are withdrawn ; and as the discs form the sides of
the arched roof, they adhere somewhat to the sides

Chap. II. GYMNADENIA CONOPSEA. 67

of the bristle. They then quickly become depressed so
as to lie in the same line with the bristle, — one a little
on one side, and the other on the other side; and if
the bristle, held in the same relative position, be now
inserted into the nectary of another flower, the two
ends of the pollinia accurately strike the two protu-
berant stigmatic surfaces, situated on each side of the
mouth of the nectary.

The flowers smell sweet, and the abundant nectar
always contained in their nectaries seems highly
attractive to Lepidoptera, for the pollinia are soon and
effectually removed. For instance, in a spike with
forty-five open flowers, forty-one had their pollinia
removed, or had pollen left on their stigmas: in
another spike with fifty-four flowers, thirty-seven had
both pollinia, and fifteen had one pollinium, removed ;
so that only two flowers in the whole spike had neither
pollinium removed.

My son George went at night to a bank where
this species grows plentifully, and soon caught Plusia
chrysitis with six pollinia, P. gamma with three, Anaitis
plagiata with five, and Triphsena pronuba with seven
pollinia attached to their proboscides. I may add
that he also caught the first-named moth in my
flower-garden, with the pollinia of this Orchis attached
to its proboscis, but with all the pollen-grains removed,
although the garden is a quarter of a mile distant from
any spot where the plant grows. Many of the above
moths had only a single pollinium attached, somewhat
laterally to their proboscides ; and this would happen
in every case, unless the moth stood directly in front
of the nectary and inserted it proboscis exactly be-
tween the two discs. But as the labellum is rather
broad and flat, with no guiding ridges like those on
the labellum of Orchis pyramidalis, there is nothing to

68 OPHRE^J. Chap. II.

compel moths to insert their proboscides symmetrically
into the nectary, and there would be no advantage in
their doing so.

Gymnadenia alUcta. — The structure of the flower of
this species resembles in most respects that of the
last ; but, owing to the upturning of the labellum, it
is rendered almost tubular. The naked elongated
discs are minute and approximate. The stigmatic sur-
faces are partially lateral and divergent. The nectary
is short, and full of nectar. Small as the flowers are,
they seem highly attractive to insects : of the eighteen
lower flowers on one spike, ten had both, and seven
had one pollinium removed ; on some older spikes all
the pollinia had been removed, except from two or
three of the uppermost flowers.

Gymnadenia odoratissima is an inhabitant of the
Alps, and is said by Dr. H. Muller* to resemble in
all the above characters G. conopsea. As the flowers,
which are pale coloured and highly perfumed, are not
visited by butterflies, he believes that they are fertilised
exclusively by moths. The North American G. tri-
dentata, described by Professor Asa Gray,f differs in an
important manner from the foregoing species. The
anther opens in the bud, and the pollen-grains, which
m the British species are tied together by very weak
threads, are here much more incoherent, and some in-
variably fall on the two stigmas and on the naked
cellular tip of the rostellum ; and this latter part,
strange to say, is penetrated by the pollen-tubes. The
flowers are thus self-fertilised. Nevertheless, as Pro-
fessor Gray adds, " all the arrangements for the removal

* « Nature,' Dec. 31, 1874, p. note p. 260 ; and vol. xxxvi. 1863,

109. p. 293. In the latter paper he

t ' American Journal of Science,' adds some remarks on G.flava and

Tol. xxxiv. 1862, p. 426, and foot- nivea.

Chap. II.

HABENAKIA CHLORANTHA.

69

of the pollinia by insects, including the movement of
depression, are as perfect as in the species which
depend upon insect aid." Hence there can be little
doubt that this species is occasionally cross-fertilised.

Fig. 11.

HABENARIA CHLORANTHA, OR BUTTERFLY ORCHIS.

a a. anther-cells.

d. disc of pollinium.

s. stigma.

n. nectary.

n'. orifice of nectary.

I. labellum.

A. Flower viewed in front, with all
the sepals and petals removed
except the labellum with its
nectary, which is turned to one
side.

B. A pollinium. (This has hardly

a sufficiently elongated appear-
ance.) The drum-like pedicel
is hidden behind the disc.

C. Diagram, giving a section

through the viscid disc, the
drum-like pedicel, and the
attached end of the caudicle.
The viscid disc is formed of an
upper membrane with a layer
of viscid matter beneath.

Habenaria or Platanthera chlorantha. — The pollinia
of the Large Butterfly Orchis differ considerably from
those of any species hitherto mentioned. The two

70 OPHKE^E. Chap. II.

anther-cells are separated from each other by a wide
space of connective membrane, and the pollinia are
enclosed in a backward sloping position (fig. 11). The
viscid discs front each other, and stand in advance of
the stigmatic surface. In consequence of their forward
position, the caudicles and pollen-masses are much
elongated. Each viscid disc is circular, and, in the
early bud, consists of a mass of cells, of which the
exterior layers (answering to the lip or pouch in
Orchis) resolve themselves into adhesive matter. This
matter has the property of remaining adhesive for at
least twenty-four hours after the pollinium has been
removed from its cell. The disc, externally covered
with a thick layer of adhesive matter (see fig. C,
which stands so that the layer of viscid matter is below)
is produced on its opposite and embedded side into
a short drum-like pedicel. This pedicel is continuous
with the membranous portion of the disc and is formed
of the same tissue. The caudicle of the pollinium is
attached in a transverse direction to the embedded end
of the pedicel, and its extremity is prolonged, as a bent
rudimentary tail, just beyond the drum. The caudicle
is thus united to the viscid disc in a very different
manner, and in a plane at right angles, to what occurs
in the other British Orchids. In the short drum-
like pedicel, we have a small development of the long
pedicel of the rostellum, which is so conspicuous in
many Vandeae, and which connects the viscid disc with
the true caudicles of the pollinia.

The drum-like pedicel is of the highest importance,
not only by rendering the viscid disc more prominent
and more likely to stick to the face of an insect whilst
inserting its proboscis into the nectary beneath the
stigma, but on account of its power of contraction.
The pollinia lie inclined backwards in their cells (see

Chap. II. HABENARIA CHLORANTHA. 71

fig. A), above and some way on each side of the stig-
matic surface ; if attached in this position to the head
of an insect, the insect might visit any number of
flowers, and no pollen would be left on the stigma.
But observe what takes place : in a few seconds after the
inner end of the drum-like pedicel has been removed
from its embedded position and exposed to the air, one
side of the drum contracts, and this contraction draws
the thick end of the pollinium inwards, so that the
caudicle and the viscid surface of the disc are no longer
parallel, as they were at first, and as they are repre-
sented in the section, iig. C. At the same time the
drum rotates through nearly a quarter of a circle, and
this moves the caudicle downwards, like the hand of
a clock, depressing the thick end of the pollinium or
mass of pollen-grains. Let us suppose the right-hand
disc to be affixed to the right side of an insect's face,
and by the time required for the insect to visit
another flower on another plant, the pollen-bearing
end of the pollinium will have moved downwards
and inwards, and will now infallibly strike the viscid
surface of the stigma, situated in the middle of the
flower beneath and between the two anther-cells.

The little rudimentary tail of the caudicle projecting
beyond the drum-like pedicel is an interesting point
to those who believe in the modification of species ;
for it shows us that the disc has been carried a little
inwards, and that primordially the two discs stood even
still further in advance of the stigma than they do
at present. We thus learn that the parent-form ap-
proached in this respect the structure of that extra-
ordinary Orchid, the Bonatea speciosa of the Cape of
Good Hope.

The remarkable length of the nectary, containing
much free nectar, the white colour of the conspicuous

72 OPHRE^E. Chap. II.

flowers, and the strong sweet odour emitted by them at
night, all show tnat this plant depends for its fertilisa-
tion on the larger nocturnal Lepidoptera. I have
often found spikes with almost all the pollinia removed.
From the lateral position and distance of the two
viscid discs from each other, the same moth would
generally remove only one pollinium at a time ; and
in a spike which had not as yet been much visited,
three flowers had both pollinia, and eight flowers had
only one pollinium removed. From the position of
the discs it might have been anticipated that they
would adhere to the side of the head or face of moths ;
and Mr. F. Bond sent me a specimen of Hadena dentina
with one eye covered and blinded by a disc, and a
specimen of Plusia v. aureum with a disc attached to
the edge of the eye. Mr. Marshall* collected twenty
specimens of Cucullia umhratica on an island in Der-
wentwater, separated by half-a-mile of water from any
spot where H. chlorantha grew ; nevertheless, seven of
these moths had the pollinia of this Orchid affixed to
their eyes. Although the discs are so adhesive that
almost all the pollinia in a bunch of flowers which was
carried in my hand and thus shaken were removed
by adhering to the petals or sepals, yet it is certain
that moths, probably the smaller species, often visit
these flowers without removing the pollinia; for on
examining the discs of a large number of pollinia
whilst still in their cells I found minute Lepido-
pterous scales glued to them.

The cause of the flowers of various kinds of Orchids
being constructed so that the pollinia are always
affixed to the eyes or proboscides of Lepidoptera, and
to the naked foreheads or proboscides of Hymenoptera,

* 'Nature/ Sept. 12, 1872, p. 393.

Chap. II. HABENARIA BIFOLIA. 73

no doubt is that the viscid discs cannot adhere to
a scaly or very hairy surface; the scales themselves
being easily detached. Variations in the structure of
the flower of an Orchid, unless they led to the viscid
discs touching some part of the body of an insect
where they would remain firmly attached, would be of
no service, but an injury to the plant ; and consequently
such variations would not be preserved and perfected.

Hdbenaria bifolia, or Lesser Butterfly Orchis. — I am
aware that this form and the last are considered by
Mr. Bentham and by some other botanists as mere
varieties of one another ; for it is said that intermediate
gradations in the position of the viscid discs occur.
But we shall immediately see that the two forms
differ in a large number of other characters, not to
mention general aspect and the stations inhabited, with
which, we are not here concerned. Should these two
forms be hereafter proved to graduate into each other,
independently of hybridisation, it would be a remarkable
case of variation ; and I, for one, should be as much
pleased as surprised at the fact, for these two forms
certainly differ from one another more than do most
species belonging to the same genus.

The viscid discs of the Lesser Butterfly Orchis are
oval, and face each other. They stand far closer
together than in the last species ; so much so, that in
the bud, when their surfaces are cellular, they almost
touch. They are not placed so low down relatively to
the mouth of the nectary. The viscid matter is of
a somewhat different chemical nature, as shown by
its much greater viscidity, if after having been long
dried it is moistened, or after being kept in weak
spirits of wine. The drum-like pedicel can hardly be
said to be present, but is represented by a longitudinal
ridge, truncated at the end where the caudicle is

74

OPHRE^a.

Chap. II.

attached, and there is

mentary tail. In fig.

Fig. 12.

B. Disc and caudicle of H. chlo-
rantha, seen from above,
with the drum-like pedicel
fore-shortened.

A. Disc and caudicle of //. bi-
folia, seen from above.

hardly a vestige of the rudi-
12 the discs of both species,
of the proper proportional
sizes, are represented as seen
vertically from above. The
pollinia, after removal from
their cells, undergo nearly the
same movements as in the last
species. In both forms the
movement is well shown by
removing a pollinium by the
thick end with a pair of pin-
cers, and holding it under the microscope, when the
plane of the viscid disc will be seen to move through
an angle of at least forty-five degrees. The caudicles
of the Lesser Butterfly Orchis are relatively very much
shorter than in the other species; the little packets
of pollen are shorter, whiter, and, in a mature flower,
separate much more readily from one another. Lastly,
the stigmatic surface is differently shaped, being more
plainly tripartite, with two lateral prominences, situ-
ated beneath the viscid discs. These prominences
contract the mouth of the nectary, making it sub-
quadrangular. Hence I cannot doubt that the Larger
and Lesser Butterfly Orchids are distinct species,
masked by close external similarity.*

As soon as I had examined the present species,

* According to Dr. H. Miiller,
Habenaria or Platanthera bifolia
of English authors is the P. sol-
stitialis of Buenninghausen ; and
he fully agrees with rae that it
must be ranked as specitically
distinct from P. chlorantha. Dr.
Miiller states that this latter
species is connected by a series
of gradaiions with another forui

which in Germany is called P.
bifolia. He gives a very full and
interesting account of the varia-
bility of these three forms of
Platanthera, and of their structure
in relation to their manner of fer-
tilisation : * Verhandl. d. Nat.
Verein. f. Pr. Kh. u. Westfal.'
Jahrg. xxv. III. Folge, v. Bd. pp.
3G-38.

Chap. II. PLATANTHERA. 75

I felt convinced, from the position of the viscid discs,
that it would be fertilised in a different manner from
the Larger Butterfly Orchis ; and now, owing to the
kindness of Mr. F. Bond, I have examined two moths,
namely, Agrotis segetum and Anaitis jplagiata, one with
three pollinia, and the other with five pollinia, attached,
not to the eyes and side of the face as in the last
species, but to the base of the proboscis. I may
remark that the pollinia of these two species of Habe-
naria, when attached to moths, can be distinguished at
a glance.

Professor Asa Gray has described* the structure of
no less than ten American species of Platanthera.
Most of them resemble in their manner of fertilisation
the two British species ; but some of the species, in
which the viscid discs do not stand far apart, have
curious contrivances, such as a channelled labellum,
lateral shields, &c, compelling moths to insert their
proboscides directly in front. P. hookeri, on the other
hand, differs in a very interesting manner : the two
viscid discs stand widely separated from each other ;
consequently a moth, unless of gigantic size, would be
able to suck the copious nectar without touching either
disc ; but this risk is avoided in the following manner :
— the central line of the stigma is prominent, and the
labellum, instead of hanging down, as in most of the
other species, is curved upwards, so that the front of
the flower is made somewhat tubular and is divided
into halves. Thus a moth is compelled to go to the
one or other side, and its face will almost certainly be
brought into contact with one of the discs. The drum
of the pollinium, when removed, contracts in the
same manner as I have described under P. chlorantha.

* 'American Journal of Science,' vol. xxxiv. 18G2, pp. 113, 2f»f),
and 424, and vol. xxxvi. 1863, p. 292.

76 OPHEE^. Chap. II.

Professor Gray has seen a butterfly (Nisoniades) from
Canada with a polliniuni of this species attached to
each eye. In the case of P. flava, moths are compelled
in a different manner to enter the nectary on one side.
A narrow but strong protuberance, rising from the base
of the labellum, projects upwards and backwards, so
as almost to touch the column ; thus the moth, being
forced to go to either side, is almost sure to withdraw
one of the viscid discs. P. liyperborea and dilatata
have been regarded by some botanists as varieties of
the same species; and Professor Asa Gray says that
he was formerly tempted to come to the same con-
clusion; but on closer examination he finds, besides
other characters, a remarkable physiological difference,
namely, that P. dilatata, like its congeners, requires
insect aid and cannot fertilise itself; whilst in P.
hyperhorea the pollen-masses commonly fall out of the
anther-cells whilst the flower is very young or in bud,
and thus the stigma is self-fertilised. Nevertheless, the
various structures adapted for crossing are still present.*
The genus Bonatea is closely allied to Habenaria,
and includes plants having an extraordinary structure.
Bonatea speciosa is an inhabitant of the Cape of Good
Hope, and has been carefully described by Mr. Trimen ;f
but it is impossible to explain its structure without
drawings. It is remarkable from the manner in which
the two stigmatic surfaces, as well as the two viscid
discs, project far out in front of the flower, and from
the complex nature of the labellum, which consists of
seven, or probably of nine distinct parts all fused

* Mr. J. Mansel Weale has de- pollinia not undergoing any move-
scribed ('Journ. Lin. Soc. Bot.' men t or change of position when
vol. xiii. 1871, p. 47) the method of removed from their cases,
fertilisation of two South African f ' Journ. Linn. Soc. Bot.' vol.
species of Habenaria : one of ix. 1865, p. 156.
these is remarkable from the

Chap. II. BONATEA SPECIOSA. 77

together. As in Platanihera flava, there is a process
at the base of the labellum which compels moths to
enter the flower on either side. The nectary, accord-
ing to Mr. Trimen and Mr. J. Mansel Weale, does not
contain free nectar ; but the latter author believes
that the tissue of which it is composed tastes sweet, so
that moths probably penetrate it for the sake of the
intercellular fluid. The pollinia are of astonishing
length, and when removed from their cases hang down
merely from the weight of the pollen-masses, and if
attached to the head of an insect would be in a proper
position for adhering to the stigma. Mr. Weale has
likewise described some other South African species
of Bonatea.* These differ from B. speciosa in having
their nectaries full of nectar. He found a small
butterfly, Pyrgus elmo, " perfectly embarrassed by the
number of pollinia of this Bonatea attached to its
sternum." But he does not specify whether the
sternum was naked or covered with scales.

The South African genera Disa and Disperis are
placed by Lindley in two sub-tribes of the Ophreae.
The superb flowers of Disa grandijlora have been
described and figured by Mr. Trimen.f The posterior
sepal, instead of the labellum, is developed into a large
nectary. In order that insects may reach the copiously
stored nectar, they must insert their proboscides on
either side of the column; and in accordance with
this fact the viscid discs are turned outwards in an
extraordinary manner. The pollinia are crooked, and
when removed bend downwards from their own weight,
so that no movement is necessary for placing themselves
in a proper position. Considering the large supply of

* ' Journ. Linn. Soc. Bot.' vol. f ' Journ. Linn. Soc. Bot.' vol.
x. p. 470. vii. 1863, p. 144.

78 OPHRE^l. Chap. II.

nectar and that the flowers are very conspicuous, it
is remarkable that they are rarely visited by insects.
Mr. Trimen wrote to me in 1864 that he had lately
examined seventy-eight flowers, and only twelve of
these had one or both pollinia removed by insects,
and only five had pollen on their stigmas. He does
not know what insects occasionally fertilise the flowers ;
but Mrs. Barber has more than once seen a large fly,
allied to Bombylius, with the pollinia of Disa polygnoides
attached to the base of its proboscis. Mr. Weale states*
that D. maerantha differs from D. grandiflora and comuta
in producing plenty of seed, and is remarkable from
often fertilising itself. This follows from " a very slight
jerk, when the flower is fully expanded, sufficing to
eject the pollinia from their widely open anther-cases,
and to bring them into contact with the stigma.
This in nature is not nnseldom the case, as I have
repeatedly found many flowers thus fertilised." He
has, however, no doubt that the flowers are likewise
cross-fertilised by nocturnal insects. He adds that
D. grandifiora in being so seldom fertilised by insects
offers a case like that of Ophrys muscifera; whilst
D. maerantha in being often self-fertilised closely cor-
responds with Ophrys apifera ; but this latter species
seems to be invariably self-fertilised.

Lastly, Mr. Weale has described,! as far as he could
make out, the manner in which a species of Disperis
is fertilised by the aid of insects. It deserves notice
that the labellum and two lateral sepals of this plant
secrete nectar.

We have now finished with the Ophrese ; but before
passing on to the following tribes, I will recapitulate

* ' Journ. Linn. Soc. Bot.' vol. + ' Journ. Linn Soc. Bot/ vol.

xiii. 1871, p. 45. xiii. 1871, p. 42.

Chap. II. OPPREiE. 79

the chief facts with respect to the movements of the
pollinia, all due to the nicely regulated contraction of
that small portion of membrane (together with the
pedicel in the case of Habenaria) lying between the
layer or ball of adhesive matter and the extremity of
the caudicle. In a few cases, however, as with some
of the species of Disa and Bonatea, the caudicles when
removed from their cells do not undergo any movement ;
the weight of the pollen-masses sufficing to depress
them into a proper position. In most of the species of
Orchis the stigma lies directly beneath the anther-cells,
and the pollinia simply move vertically downwards.
In Orchis pyramidalis there are two lateral and inferior
stigmas, and the pollinia move downwards and outwards,
diverging to the proper angle, so as to strike the two
lateral stigmas. In Gymnadenia the pollinia move
only downwards, but they are adapted for striking the
lateral stigmas, by being attached to the upper lateral
surfaces of the proboscides of Lepidoptera. In Nigri-
tel]a they move upwards, but this depends merely on
their being always affixed to the lower side of the
proboscis. In Habenaria the stigmatic surface lies
beneath and between the two widely-separated anther-
cells, and the pollinia here converge, instead of diverg-
ing as in Orchis pyramidalis, and likewise move down-
wards. A poet might imagine that whilst the pollinia
were borne through the air from flower to flower,
adhering to an insect's body, they voluntarily and
eagerly placed themselves in that exact position, in
which alone they could hope to gain their wish and
perpetuate their race.

80 AEETHUSE^. Chap. III.

CHAPTER III.

ARETHUSE^E.

Cephalanthera grandiflora; rostellum aborted; early penetration of the
pollen-tubes ; case of imperfect self-fertilisation ; cross-fertilisation
effected by insects which gnaw the labellum — Cephalanthera ensi-
folia — Pogonia — Pterostylis and other Australian orchids with the
labellum sensitive to a touch — Vanilla— Sobralia.

Cephalanthera grandiflora. — This Orchid is remark-
able from not possessing a rostellum, which is so
eminently characteristic of the order. The stigma is
large, and the anther stands above it. The pollen
is extremely friable and readily adheres to any object.
The grains are tied together by a few weak elastic
threads ; but they are not cemented together, so as to
form compound pollen-grains, as in almost all other
Orchids.* In this latter character and in the complete
abortion of the rostellum we have evidence of degrada-
tion ; and Cephalanthera appears to me like a degraded
Epipactis, a member of the Neotteae, to be described in
the next chapter.

The anther opens whilst the flower is in bud and
partly expels the pollen, which stands in two nearly
free upright pillars, each nearly divided longitudinally
into halves. These subdivided pillars rest against or
even overhang the upper square edge of the stigma,
which rises to about one- third of their height (see front

* This separation of the grains by Lindley in his magnificent
was observed, and is represented, ' Illustrations of Orchidaceous
by Bauer in the plate published Plants.'

Chap. III. CEPHALANTHERA GRANDIFLORA.

81

view B, and side view C, in fig. 13). Whilst the flower
is still in bud, the pollen-grains which rest against the
upper sharp edge of the stigma (but not those in the
upper or lower parts of the mass) emit a multitude of

Ficr. 13.

B

CEPHALANTHERA GRANDIFLORA.

a anther; in the front view, B, | A. Oblique view of perfect flower,

the two cells with the included
pollen are seen.

o. one of the two lateral rudimen-
tary anthers, or auricles.

p. masses of pollen.

s. stigma.

/. distal portion of the labellum.

when fully expanded.

B. Front view of column, with all

the petals and sepals removed.

C. Side view of column, with all the

sepals and petals removed ; the
narrow pillars of pollen (p)
between the anther and stigma
can just be seen.

tubes ; and these deeply penetrate the stigmatic tissue.
Aiter this period the stigma bends a little forward, and
the result is that the two friable pillars of pollen are
drawn a little forward and stand almost completely free

82 AEETHUSE^E. Chap. IIL

from the anther-cells, being tied to the edge of the
stigma and supported by the penetration of the pollen-
tubes. Without this support the pillars would soon fall
down.

The flower stands upright, with the lower part of
the labellum turned up parallel to the column (fig. A).
The tips of the lateral petals never become separated ; *
so that the pillars of pollen are protected from the
wind, and as the flower stands upright they do not
fall down from their own weight. These are points of
much importance to the plant, as otherwise the pollen
would have been blown or fallen down and been
wasted. The labellum is formed of two portions ; when
the flower is mature, the small triangular distal portion
turns down at right angles to the basal portion ; and
thus offers a small landing-place for insects in front
of the triangular entrance, situated half-way up the
almost tubular flower. After a short time, as soon as
the flower is fully fertilised, the small distal portion
of the labellum rises up, shuts the triangular door, and
again perfectly encloses the organs of fructification.

Although I have often searched for nectar within the
cup of the labellum, I have never found even a trace.
The terminal portion of the labellum is frosted with
globular papillae of an orange colour, and within the
cup there are several transversely wrinkled, longi-
tudinal ridges of a darker orange tint. These ridges
are often gnawed by some animal, and I have found
minute, bitten-ofY fragments lying within the base of the
cup. In the summer of 1862 the flowers were visited
less frequently by insects than is usual, as shown by
the unbroken state of the pollen-masses ; nevertheless,

* Bauer figures the flowers say is that I have not seen them
much more widely expanded than in this condition,
is here represented : all that I can

Chap. III. CErilALANTHERA GRANDIFLORA. 83

out of seventeen flowers which were examined one day,
five had their ridges gnawed, and on the next day,
seven out of nine other flowers were in this state. As
there was no appearance of slime, I do not believe
that they had been attacked by slugs; but whether
they had been gnawed by winged insects, which alone
would be effectual for cross-fertilisation, I know not.
The ridges had a taste like that of the labellum of
certain Vandese, in which tribe (as we shall hereafter
see) this part of the flower is often gnawed by insects.
Cephalanthera is the only British Orchid, as far as I
have observed, which attracts insects, by thus offering
to them solid food.

The early penetration of the stigma by a multitude
of pollen-tubes, which were traced far down the stigmatic
tissue, apparently gives us another case, like that of the
Bee Ophrys, of perpetual self-fertilisation. I was much
surprised at this fact, and asked myself : Why does the
distal portion of the labellum open for a short period ?
what is the use of the great mass of pollen above and
below that layer of grains, the tubes of which alone
penetrate the upper edge of the stigma ? The stigma
has a large flat viscid surface ; and during several years
I have almost invariably found masses of pollen adher-
ing to its surface, and the friable pillars by some means
broken down. It occurred to me that, although the
flowers stand upright, and the pillars are well pro-
tected from the wind, yet that the pollen-masses might
ultimately topple over from their own weight, and so
fall on the stigma, thus completing the act of self-fer-
tilisation. Accordingly, I covered with a net a plant
having four buds, and examined the flowers as soon as
they had withered ; the broad stigmas of three of them
were perfectly free from pollen, but a little had fallen
on one corner of the fourth. With the exception of

84 ARETHUSE.E. Chap. III.

the summit of one pillar in this latter flower, all the
other pillars still stood upright and unbroken. I looked
at the flowers of some surrounding plants, and every-
where found, as I had so often done before, broken-down
pillars and masses of pollen on the stigmas.

From the usual state of the pillars of pollen, as
well as from the gnawed condition of the ridges on the
labellum, it may be safely inferred that insects of some
kind visit the flowers, disturb the pollen, and leave
masses of it on the stigmas. We thus see that the
turning down of the distal portion of the labellum, by
which a temporary landing-place and an open door are
afforded,* — the upturned labellum, by which the flower
is made tubular so that insects are compelled to crawl
close by the stigmatic surface, — the pollen readily
cohering to any object, and standing in friable pillars
protected from the wind, — and, lastly, the large masses
of pollen above and below that layer of grains, the
tubes of which alone penetrate the edge of the stigma, —
are all co-ordinated structures, far from useless ; and
they would be quite useless if these flowers were always
self- fertilised.

To ascertain how far the early penetration of the
upper edge of the stigma by the tubes of those grains
which rest on it, is effectual for fertilisation, I covered
up a plant, just before the flowers opened, and removed
the thin net as soon as they had begun to wither. From
long experience I am sure that this temporary cover-
ing could not have injured their fertility. The four
covered flowers produced seed-capsules as fine in ap-
pearance as those on any of the surrounding plants.
When ripe, I gathered them, and likewise capsules
from several of the surrounding plants, growing under
similar conditions, and weighed the seed in a chemical
balance. The seeds from the four capsules on the

Chap. III. CEPHALANTHERA GRANDIFLORA. 85

uncovered plants weighed 1 ' 5 grain ; whilst those
from an equal number of capsules on the covered plant
weighed under 1 grain ; but this does not give a fair
idea of the relative difference of their fertility, for I
observed that a great number of the seeds from the
covered plant consisted of minute and shrivelled husks.
Accordingly I mixed the seeds well together, and took
four little lots from one heap and four little lots from
the other heap, and, having soaked them in water, com-
pared them under the microscope : out of forty seeds
from the uncovered plants there were only four bad
ones, whereas out of forty seeds from the covered-up
plants there were at least twenty-seven bad ; so that
there were nearly seven times as many bad seeds from
the covered plants, as from those left free to the access
of insects.

We may therefore conclude that this orchid is
constantly self-fertilised, although in a very imperfect
manner ; but this would be highly useful to the plant,
if insects failed to visit the flowers. The penetra-
tion of the pollen-tubes, however, is apparently even
more serviceable by retaining the pillars of pollen in
their proper places, so that insects, in crawling into the
flowers, may get dusted with pollen. Self-fertilisation
also may, perhaps, be aided by insects, carrying pollen
from the same flower on to the stigma ; but an insect
thus smeared with pollen could hardly fail likewise to
cross the flowers on other plants. From the relative
position of the parts, it seems indeed probable (but I
omitted to prove this by the early removal of the
anthers, so as to observe whether pollen was brought
to the stigma from other flowers) that an insect would
more frequently get dusted by crawling out of a flower
than by crawling into one ; and this would of course
facilitate a cross between distinct individuals. Hence

ob ARETHUSE^. Chap. III.

Cephalanthera offers only a partial exception to the
rule that the flowers of Orchids are generally fertilised
by pollen from another plant.

Cephalanthera ensifolia. — According to Delpino,* the
flowers of this species are visited by insects, as shown
by the removal of the pollen-masses. He believes that
this is effected by their bodies being first rendered sticky
by means of the stigmatic secretion. It is not clear
whether the flowers also fertilise themselves. Each
pollen-mass is divided into two, instead of being merely
sub-divided, so that there are four distinct pollen-masses.

Pogonia ophioglossoides. — The flowers of this plant,
an inhabitant of the United States, resemble, as
described by Mr. Scudder, f those of Cephalanthera in
not having a rostellum, and in the pollen-masses not
being furnished with caudicles. The pollen consists of
powdery grains not united by threads. Self-fertilisation
seems to be effectually prevented ; and the flowers on
distinct plants must intercross, for each plant generally
bears only a single flower.

Pterostylis trullifolia and longifolia. — I may here
briefly mention some Orchids, inhabitants of Australia
and New Zealand, which are included by Lindley in
the same family of the Arethuseae with Cephalanthera
and Pogonia, and are remarkable from their labella
being extremely sensitive or irritable. Two of the
petals and one of the sepals form a hood which encloses
the column, as may be seen at A in the accompanying
figure of Pterostylis longifolia.

The distal portion of the labellum affords a landing-
place for insects, in nearly the same manner as with
Cephalanthera; but when this organ is touched it
rapidly springs up, carrying with it the touching insect,

* «TJlt. Osservaz. sulIa Dico f ■ Proc. Boston Soc. Nat. Hist.*

garaia,' part ii. 1875, p. 149. vol. ix. 1863, p. 182.

Chap. III.

PTEEOSTYLIS LONGIFOLIA.

87

which is thus temporarily imprisoned within the other-
wise almost completely closed flower. The labellum

Fig. 14.

Pterostylis longifolia. (Copied from Mr. R. D. Fitzgerald's ' Australian
Orchids.')

A. Flower in its natural state : the

outline of the column is dimly-
seen within.

B. Flower with the near lateral

petal removed, showing the

column with its two shields,
and the labellum in the position
which it occupies after having
been touched.

remains shut from half an hour to one hour and a
half, and on reopening is again sensitive to a touch.
Two membranous shields project on each side of the

$8

AKETHUSE^.

Chap. Ill

upper part of the column, with their edges meeting
in front, as may be seen in fig. B. In this drawing
the petal on the near side has been cut away, and
the labellum is represented in the position which it
assumes after having been touched. As soon as the
labellum has thus risen, an imprisoned insect cannot
escape except by crawling through the narrow passage
formed by the two projecting shields. In thus escaping
it can hardly fail to remove the pollinia, as, before
coming into contact with them, its body will have been
smeared with the viscid matter of the rostellum. On
being imprisoned in another flower, and on again escap-
ing by the same passage, it will almost certainly leave
at least one of the four pollen-masses on the adhesive
stigma, and thus fertilise the flower.

All that I have here said is taken from the admir-
able description given by Mr. Cheeseman * of Pterostylis
trullifolia ; but I have copied the figure of P. longifolia
from Mr. Fitzgerald's great work on the Australian
Orchids, as it shows plainly the relation of all the parts.

Mr. Cheeseman placed insects within several flowers
of P. trullifolia, and. saw them afterwards crawl out,
generally with pollinia attached to their backs. He
also proved the importance of the irritable labellum
by removing it from twelve flowers whilst young, and
in this case insects which entered the flowers would not
have been compelled to crawl out through the passage ;
and not one of these flowers produced a capsule. The
flowers seem to be frequented exclusively by Diptera ;
but what attraction they present is not known, as they
do not secrete nectar. Mr. Cheeseman believes that
hardly a quarter of the flowers produce capsules ; not-
withstanding that on one occasion he examined 110

* ' Transact. New Zealand Institute/ vol. v. 1873, p 352 ; and vol.
fii. p. 351.

Chap. III. PTEBOSTYLIS LONGIFOLIA. 89

flowers in a withered condition, and seventy-one of these
had pollen on their stigmas, and only twenty-eight had
all four pollinia still within their anthers. All the
New Zealand species bear solitary flowers, so that dis-
tinct plants cannot fail to be intercrossed. I may add
that Mr. Fitzgerald also placed a small beetle on the
labellum of P. longifolia, which was instantly carried
into the flower and imprisoned; afterwards he saw
it crawl out with two pollinia attached to its back.
Nevertheless he doubts, from reasons which seem to
me quite insufficient, whether the sensitiveness of the
labellum is not as great a disadvantage as an advan-
tage to the plant.

Mr. Fitzgerald has described another Orchid belong-
ing to the same sub-tribe, Caladenia dimorpJia, which
has an irritable labellum. He kept a plant in his room,
and says : " A house-fly lighting on the lip was carried
by its spring against the column, and becoming en-
tangled in the gluten of the stigma, and struggling to
escape, removed the pollen from the anther and smeared
it on the stigma." He adds, " Without some such aid
the species of this genus never produce seed." But
from the analogy of other Orchids we may feel sure
that insects usually behave very differently from the
fly which he saw caught on the stigma, and no doubt
they carry the pollen-masses from plant to plant. The
labellum of another Australia* genus, Calaena, one oi
the Arethusese, is said by Dr. Hooker * to be irritable ;
so that when touched by an insect it shuts up suddenly
against the column, and temporarily encloses its prey
as it were within a box. The labellum is covered by
curious papillae, which, as far as Mr. Fitzgerald has
seen, are not gnawed by insects.

1 Flora of Tasmania,' vol. ii. p. 17.

90

ARETHUSE-^E.

Chap. Ill,

Mr. Fitzgerald describes and figures several other
genera, and states with respect to Acianthus fornicatus
and exsertus that neither species produce seeds if
protected from insects, but are easily fertilised by
pollen placed on their stigmas. Mr. Cheeseman * has
witnessed the fertilisation of Acianthus sinclairii in
New Zealand, the flowers of which are incessantly
visited by Diptera, without whose aid the pollinia are
never removed. Out of eighty-seven flowers borne
by fourteen plants, no less than seventy-one matured
capsules. This plant according to the same observer
exhibits one remarkable peculiarity, namely, that the
pollen-masses are attached to the rostellum by means
of the exserted pollen-tubes, which serve as a caudicle ;
and the pollen-masses are thus removed together with
the rostellum, which is viscid, when the flowers are
visited by insects. The flowers of the allied Cyrto-
stylis are also much frequented by insects, but the
pollinia are not so regularly removed as those of the
Acianthus ; and with Corysanthes, only five out of 200
flowers produced capsules.

The Vanillidse according to Lindley form a sub-
tribe of the Arethusese. The large tubular flowers of
Vanilla aromatica are manifestly adapted to be ferti-
lised by insects ; and it is known that when this plant
is cultivated in foreign countries, for instance in Bour-
bon, Tahiti, and the East Indies, it fails to produce
its aromatic pods unless artificially fertilised. This
fact shows that some insect in its American home is
specially adapted for the work ; and that the insects
of the above-named tropical regions, where the Vanilla
flourishes, either do not visit the flowers, though they
secrete an abundance of nectar, or do not visit them

* ■ Transact. New Zealand Institute,' vol. vii. 1875, p. 349.

Chap. III. PTEROSTYLIS LONGIFOLIA. 91

in the proper manner.* I will mention only two pecu-
liarities in the structure of the flowers : the anterior
part of the pollen-masses is semi- waxy and the posterior
part somewhat friable ; the grains are not cemented
together into compound grains, and the single grains
are not united by fine elastic threads but by viscid
matter; this matter would aid in causing the pollen
to adhere to an insect, but I should have thought that
such aid was superfluous, as the viscid rostellum is
well developed. The other peculiarity is that the
labellum, in front of the stigma, and some way beneath
it, is furnished with a stiff hinged brush, formed of a
series of combs one over the other, which point down-
wards. This structure would allow an insect to crawl
easily into a flower, but would compel it whilst re-
treating to press close against the column ; and in
doing so it would remove the pollen-masses, leaving
them on the stigma of the next flower which was
visited.

The genus Sobralia is allied to Vanilla, and Mr.
Cavendish Browne informs me that he saw a large
humble-bee enter a flower of S. macrantha in his
hothouse, and when it crawled out it had the two
large pollen- masses firmly fixed to its back, nearer to
the tail than to the head. The bee then looked about,
and seeing no other flower re-entered the same one of

* For Bourbon see 'Bui. Soc. in the Blue Mountains of New
Bot. de France,' torn. i. 1854, p. South Wales; removed from
290. For Tahiti see H. A. Tilley, thence to Sydney, a number of
'Japan, the Amour, &e.,' 1861, p. plants, though flowering well, have
375. For the East Indies see not borne any seed if left to them-
Morren in 'Annals and Mag. of selves, though invariably fertile
Nat. Hist.' 1839, vol. iii. p. 6. I when the pollen-masses were re-
may give an analogous but more moved and placed on the stigma."
striking case from Mr Fitzgerald, Yet the Blue Mountains are less
who says "that Sarcochilus par- than one hundred miles distant
viflorus (one of the Vandeae) pro- from Sydney,
duces capsules not unfrequently

92 ARETHUSE^E. Chap. III.

the Sobralia, but quickly retreated, leaving the pollen-
masses on the stigma, with the viscid discs alone
adhering to its back. The nectar of this Guatemala
Orchid seemed too powerful for our British bee, for it
stretched out its legs and lay for a time as if dead on
the labellum, but afterwards recovered.

Chap. IV. EPIPACTIS PALUSTEIS. 93

CHAPTEE IV.

NEOTTE^].

Epipactis palustris ; curious shape of the labellum and its importance
in the fructification of the flower — Other species of Epipactis —
Epipogium — Goodyera repens — Spiranthes autumnalis; perfect
adaptation by which the pollen of a younger flower is carried to the
stigma of an older flower on another plant — Listera ovata ; sensi-
tiveness of the rostellum; explosion of viscid matter; action of
insects ; perfect adaptation of the several organs — Listera cordata —
Neottia nidus-avis ; its fertilisation effected in the same manner as
in Listera — Thelymitra, self-fertile.

We have now arrived at a third tribe, the Neotteas of
Lindley, which includes several British genera. These
present many interesting points with respect to their
structure and manner of fertilisation.

The Neotteae have a free anther standing behind the
stigma. Their pollen-grains are tied together by fine
elastic threads, which partially cohere and project at
the upper end of the pollen-mass, being there attached
(with some exceptions) to the back of the rostellum.
Consequently the pollen-masses have no true and dis-
tinct caudicles. In one genus alone (Goodyera) the
pollen-grains are collected into packets as in Orchis.
Epipactis and Goodyera agree pretty closely in their
manner of fertilisation with the Ophreae, but are more
simply organised. Spiranthes comes under the same
category, but has been differently modified in some
respects.

Epipactis palustris* — The lower part of the large

* I am much indebted to Mr. ing me fresh specimens of this
A. G. More, of Bembridge, in the beautiful Orchis.
Isle of Wight, for repeatedly send-

94

NEOTTE.E.

Chap. IV.

EPIPACTIS PALUST1US.

a. anther, with the two open cells
seen in the front view D.

a', rudin entary anther, or auricle,
referred to in a future chapter.

r. rostellum.

s. stigma.

I. labeilum.

A. Side view of flower, with the

lower sepals removed, in its
natural position.

B. Side view of flower, with the

distal portion of the labeilum
depressed, as if by the weight
of an insect.

C. Side view of flower, somewhat

enlarged, with all the sepals
and petals removed, excepting
the labeilum, of which the
near side has been cut away ;
the massive anther is seen to
be of large size.
D. Front view of column, somewhat
enlarged, with all the sepals
and petals removed: the ros-
tellum has sunk down a little
in the specimen figured, and
ought to have stood higher,
so as to hide more of the
anther-cells.

Chap. IV. EPIPACTIS PALUSTRIS. 95

stigma is bilobed and projects in front of the column
(see s in the side and front views, C, D, fig. 15). On
its square summit a single, nearly globular rostellum
is seated. The anterior face of the rostellum (r, C, D)
projects a little beyond the surface of the upper part of
the stigma, and this is of importance. In the early bud
the rostellum consists of a friable mass of cells, with the
exterior surface rough : these superficial cells undergo
a great change during development, and become con-
verted into a soft, smooth, highly elastic membrane or
tissue, so excessively tender that it can be penetrated
by a human hair; when thus penetrated, or when
slightly rubbed, the surface becomes milky and in some
degree viscid, so that the pollen-grains adhere to it.
In some cases, though I observed this more plainly in
Epipadis latifolia, the surface of the rostellum appa-
rently becomes milky and viscid without having been
touched. This exterior soft elastic membrane forms
a cap to the rostellum, and is internally lined with a
layer of much more adhesive matter, which, when ex-
posed to the air, dries in from five to ten minutes.
By a slight upward and backward push with any object,
the whole cap, with its viscid lining, is removed with
the greatest ease ; a minute square stump, the basis
of the rostellum, being alone left on the summit of the
stigma.

In the bud-state the anther stands quite free behind
the rostellum and stigma; it opens longitudinally
whilst the flower is still unexpanded, and exposes the
two oval pollen-masses, which now lie loose in their
cells. The pollen consists of spherical granules, co-
hering in fours, but not affecting each other's shapes :
and these compound grains are tied together by fine
elastic threads. The threads are collected into bundles
extending longitudinally along the middle line of the

96 NE0TTE2E. Chap. IV

front of each pollinium, where it comes into contact
with the back of tne uppermost part of the rostellum.
From the number of these threads this middle line
looks brown, and each pollen-mass here shows a
tendency to divide longitudinally into halves. In all
these respects there is a close general resemblance to
the pollinia of the Ophrese.

The line where the parallel threads are the most
numerous is the line of greatest strength ; elsewhere
the pollen-masses are extremely friable, so that large
portions can easily be broken off. In the bud-state
the rostellum is curved a little backwards, and is
pressed against the recently-opened anther ; and the
above-mentioned slightly projecting bundles of threads
become firmly attached to the posterior flap of the
membranous cap of the rostellum. The point of attach-
ment lies a little beneath the summit of the pollen-
masses ; but the exact point is somewhat variable, for
I have met with specimens in which the attachment
was one-fifth of the length of the pollen-masses from
their summits. This variability is so far interesting,
as it is a step leading to the structure of the Ophrese,
in which the confluent threads, or caudicles, always
spring from the lower ends of the pollen-masses. After
the pollinia are firmly attached by their threads to
the back of the rostellum, the rostellum bends a little
forwards, and this partly draws the pollinia out of the
anther-cells. The upper end of the anther consists of a
blunt, solid point, not including pollen ; this blunt point
projects slightly beyond the face of the rostellum,
which circumstance, as we shall see, is important.

The flowers stand out (fig. A) almost horiozontally
from the stem. The labellum is curiously shaped, as
may be seen in the drawings : the distal half, which
projects beyond the other petals and forms an excellent

Chap. IV. EPIPACTIS PALUSTRIS. 97

landing-place for insects, is joined to the basal half by
a narrow hinge, and naturally (fig. A) is turned a little
upwards, so that its edges pass within the edges of the
basal portion. So flexible and elastic is the hinge that
the weight of even a fly, as Mr. More informs me,
depresses the distal portion ; it is represented in fig. B
in this state ; but when the weight is removed it
instantly springs up to its former position (fig. A), and
with its curious medial ridges partly closes the entrance
into the flower. The basal portion of the labellum forms
a cup, which at the proper time is filled with nectar.

Now let us see how all the parts, which I have been
obliged to describe in detail, act. When I first ex-
amined these flowers I was much perplexed : trying in
the same manner as I should have done with a true
Orchis, I slightly pushed the protuberant rostellum
downwards, and it was easily ruptured ; some of the
viscid matter was withdrawn, but the pollinia remained
in their cells. Keflecting on the structure of the
flower, it occurred to me that an insect in entering one
in order to suck the nectar, would depress the distal
portion of the labellum, and consequently would not
touch the rostellum ; but that, when within the flower,
it would be almost compelled, from the springing up
of this distal half of the labellum, to rise a little up-
wards and back out parallel to the stigma. I then
brushed the rostellum lightly upwards and backwards
with the end of a feather and other such objects ; and
it was pretty to see how easily the membranous cap
of the rostellum came off, and how well from its elas-
ticity it fitted any object, whatever its shape might be,
and how firmly it clung to the object owing to the
viscidity of its under surface. Large masses of pollen,
adhering by the elastic threads to the cap of the ros-
tellum were at the same time withdrawn.

98 NEOTTE^. Chap. IV.

Nevertheless the pollen-masses were not removed
nearly so cleanly as those which had been naturally
removed by insects. I tried dozens of flowers, always
with the same imperfect result. It then occurred to
me, that an insect in backing out of the flower would
naturally push with some part of its body against the
blunt and projecting upper end of the anther, which
overhangs the stigmatic surface. Accordingly I so
held a brush that, whilst brushing upwards against the
rostellum, I pushed against the blunt solid end of the
anther (see fig. C) ; this at once eased the pollinia, and
they were withdrawn in an entire state. At last I
understood the mechanism of the flower.

The large anther stands above and behind the
stigma, forming an angle with it (fig. C), so that the
pollinia when withdrawn by an insect would adhere
to its head or body in a position fitted to strike the
sloping stigmatic surface as soon as another flower
was visited. Hence we have not here, or in any of
the Neotteas, that movement of depression so common
with the pollinia of the Ophrese. When an insect
with the pollinia attached to its back or head enters
another flower, the easy depression of the distal portion
of the labellum probably plays an important part ; for
the pollen-masses are extremely friable, and if they
were struck against the tips of the petals much of the
pollen would be lost ; but as it is, an open gangway
is offered, and the viscid stigma, with its lower pro-
tuberant part lying in front, is the first object against
which the pollen-masses projecting forwards from the
insect's head or back would naturally strike. I may
add that in one large lot of flower-spikes, a great
majority of the pollinia had been naturally and
cleanly removed.

In order to ascertain whether I was right in believing

Chap. IV. EPIPACTIS PALUSTKIS. 99

that the distal hinged portion of the labellum was of
importance in the fertilisation of the flowers, I asked
Mr. More to remove this part from some young flowers,
and to mark them. He tried the experiment on eleven
flowers, three of which did not produce seed-capsules;
but this may have been accidental. Of the eight
capsules which were produced, two contained about as
many seeds as those from unmutilated flowers on the
same plant ; but six capsules contained much fewer
seeds. Most of the seeds were well-formed. These
experiments, as far as they go, support the view that
the distal part of the labellum is of importance in
causing insects to enter and leave the flowers in the
best manner for their fertilisation.

Since the appearance of the first edition of this book,
my son William has observed for me this Epipactis in
the Isle of Wight. Hive-bees seem to be the chief
agents in fertilisation ; for he saw them visit about a
score of flowers, and many had pollen-masses attached
to their foreheads, just above the mandibles. I had
supposed that insects always crawled into the flowers ;
but hive-bees are too large to do this; they always
clung, whilst sucking the nectar, to the distal and
hinged half of the labellum, which was thus pressed
downwards. Owing to this part being elastic and
tending to spring up, the bees, as they left the flowers,
seemed to fly rather upwards ; and this favoured, in
the manner previously explained, the complete with-
drawal of the pollen-masses, quite as well as if the
insects had crawled, in an upward direction, out of
the flower. Perhaps the upward movement may not
be so necessary in all cases as I had supposed ; for,
judging from the manner in which the pollen-masses
were attached to the hive-bees, the back part of their
heads could hardly fail to press against and lift up the

100 NEOTTE.E. Chap. IV,

blunt, solid, upper end of the anther, thus freeing the
pollen-masses. Various other insects besides hive-bees
visit the flowers. My son saw several large flies (Sar-
cophaga carnosa) haunting them; but they did not
enter in so neat and regular a manner as the hive-bees ;
nevertheless two had pollen-masses attached to their
foreheads. Several smaller flies (Coelopa frigida) were
also seen entering and leaving the flowers, with pollen-
masses adhering rather irregularly to the dorsal surface
of the thorax. Three or four distinct kinds of Hymen-
optera (one of small size being Crabro hrevis) likewise
visited the flowers ; and three of these Hymenoptera
had pollen-masses attached to their backs. Other still
more minute Diptera, Coleoptera, and ants were seen
sucking the nectar ; but these insects appeared to be
too small to transport the pollen-masses. It is re-
markable that some of the foregoing insects should
visit the flowers ; for Mr. F. Walker informs me that
the Sarcophaga frequents decaying animal matter, and
the Coelopa haunts seaweed, occasionally settling on
flowers. The Crabro also, as I hear from Mr. F. Smith,
collects small beetles (Halticae) for provisioning its
nest. It is equally remarkable, seeing how many
kinds of insects visit this Epipactis, that although my
son watched hundreds of plants for some hours on three
occasions, not a single humble-bee alighted on a flower,
though many were flying about.

Epipactis latifolia. — This species agrees with the
last in most respects. The rostellum, however, projects
considerably further beyond the face of the stigma,
and the blunt upper end of the anther less so. The
viscid matter lining the elastic cap of the rostellum
takes a longer time to get dry. The upper petals and
sepals are more widely expanded than in E. palustris :
the distal portion of the labellum is smaller, and is

Chap. IV. EPIPACTIS LATIFOLIA. 101

firmly united to the basal portion (fig. 16), so that it
is not flexible and elastic ; it apparently serves only as
a landing-place for insects. The fertilisation of this
species depends simply on an insect striking in an
upward and backward direction the highly-protuberant
rostellum, which it would be apt to do when retreating
from the flower after having sucked the copious nectar

Ficr 16.

EPIPACTIS LATIFOLIA.

Flower viewed sideways, with all the sepals and petals removed, except the
labellum.

a. anther. $. stigma,

r. rostellum. /. labellum.

in the cup of the labellum. Apparently it is not at
all necessary that the insect should push upwards the
blunt upper end of the anther ; at least I found that
the pollinia could be removed easily by simply drag-
ging off the cap of the rostellum in an upward or
backward direction.

As some plants grew close to my house, I have been
able to observe here and elsewhere their manner of
fertilisation during several years. Although hive-bees
and humble-bees of many kinds were constantly flying
over the plants, I never saw a bee or any Dipterous
insect visit the flowers ; but in Germany Sprengel
caught a fly with the pollinia of this plant attached
to its back. On the other hand I have repeatedly

102 NEOTTEiE. Chap. FV.

observed the common wasp (Vespa sylvestris) sucking
the nectar out of the open cup-shaped labellum. I
thus saw the act of fertilisation effected by the pollen-
masses being removed by the wasps, and afterwards
carried attached to their foreheads to other flowers.
Mr. Oxenden also informs me that a large bed of
E. purpurata (which is considered by some botanists to
•be a distinct species, and by others a variety) was fre-
quented by " swarms of wasps." It is very remarkable
that the sweet nectar of this Epipactis should not be
attractive to any kind of bee. If wasps were to become
extinct in any district, so probably would the Epipactis
latifolia.

To show how effectually the flowers are fertilised, 1
may add that during the wet and cold season of 1860 a
friend in Sussex examined five spikes bearing eighty-five
expanded flowers ; of these, fifty-three had the pollinia
removed, and thirty-two had them in place : but as
many of the latter were immediately beneath the buds,
a larger number would almost certainly have been
afterwards remowed. In Devonshire I found a spike
with nine open flowers, and the pollinia in all were re-
moved with one exception, and in this case a fly, too
small to remove the pollinia, had become glued to the
rostellum, and had there miserably perished.

Dr. H. Miiller has published * some interesting
observations on the difference in structure and manner
of fertilisation, as well as on the intermediate forms
between Epipactis ruhiginosa, microphylla, and viridi-
flora. The latter species is remarkable for the absence
of a rostellum, and for being regularly self-fertilised.
Self-fertilisation here follows from the incoherent
pollen-grains in the lower part of the pollen-masses

* 'Veihandl. d. Nat. Ver. f. Westfal.' Jalirg. xxv. III. Folge, v.Bd.
pp. 7-36.

Chap. IV. GOODYEKA KEPENS. 103

emitting, whilst still within the anther-cells, their
tubes, which penetrate the stigma ; and this occurs even
in the bud. This species, however, is probably visited
by insects, and occasionally crossed ; for the labellum
contains nectar. E. microphylla is intermediate in
structure between E. latifolia, which is always fertilised
by the aid of insects, and E. viridiflora, which does not
necessarily require any such aid. The whole of this
memoir by Dr. H. Muller deserves to be attentively
studied.

Ejripogium gmelini. — This plant, which has only
once been found in Great Britain, has been fully de-
scribed by Dr. Eohrbach in a special memoir. * The
structure and manner of fertilisation is in many re-
spects like that of Epipactis, to which genus the author
believes the present one to be allied, though placed by
Lindley amongst the Arethuseae. Eohrbach saw the
flowers visited by Bomhus lucorum, but it appears that
only a few produce capsules.

Goody era repens.~\ — This genus is rather closely re-
lated to Epipactis, in most of the characters with
which we are concerned. The shield-like rostellum is
almost square, and projects beyond the stigma ; it is
supported on each side by sloping sides rising from
the upper edge of the stigma, in nearly the same
manner as we shall presently see in Spiranthes. The
surface of the protuberant part of the rostellum is rough,
and when dry can be seen to be formed of cells ; it is
delicate, and, when slightly pricked, a little milky
viscid fluid exudes ; it is lined by a layer of verj
adhesive matter, which quickly sets hard when exposed

* 'Ueber den Bliithenbau von f Specimens of this rare High-

Epipogium,' &c. 1866 ; see also land Orchid were kindly sent me

lrmisch, 'Beitr'age zur Biologie by the Rev. G. Gordon of Elgin.
der Orchideen,' 1853, p. 55.

104 NEOTTE^E. Chap. IV.

to the air. The protuberant surface of the rostellum,
when gently rubbed upwards, is easily removed, and
carries with it a strip of membrane, to the hinder part
of which the pollinia are attached. The sloping sides
which support the rostellum are not removed at the
same time, but remain projecting up like a fork and
soon wither. The anther is borne on a broad elon-
gated filament ; and a membrane on both sides unites
this filament to the edges of the stigma, forming an
imperfect cup or clinandrum. The anther-cells open
in the bud, and the pollen-masses become attached
by their anterior faces, just beneath their summits,
to the back of the rostellum. Ultimately the anther
opens widely, leaving the pollinia almost naked, but
partially protected within the membranous cup or
clinandrum. Each pollinium is partially divided
lengthways ; the pollen-grains cohere in subtriangular
packets, including a multitude of compound grains, each
consisting of four grains ; and these packets are tied
together by strong elastic threads, which at their upper
ends run together and form a single flattened brown
elastic ribbon, of which the truncated extremity adheres
to the back of the rostellum.

The surface of the orbicular stigma is remarkably
viscid, which is necessary in order that the unusually
strong threads connecting the packets of pollen should
be ruptured. The labellum is partially divided into
two portions ; the terminal portion is reflexed, and
the basal portion is cup-formed and filled with nectar.
The passage between the rostellum and labellum is
contracted whilst the flower is young ; but when mature
the column moves further back from the labellum, so
as to allow of insects with the pollinia adhering to
their proboscides, to enter the flowers more freely. In
many of the specimens received, the pollinia had been

Chap. IV. GOODYEEA REFENS. 105

removed, and the fork-shaped supporting sides of the
rostelluni were partially withered. Mr. K. B. Thomson
informs me that in the north of Scotland he saw many
humble-bees (Bombus pratorum) visiting the flowers
with pollen-masses attached to their proboscides.
This species grows also in the United States; and
Professor Asa Gray * confirms my account of its
structure and manner of fertilisation, which is likewise
applicable to another and very distinct species, namely,
Goody era pubescens.

Goodyera is an interesting connecting link between
several very distinct forms. In no other member of
the Neotteae observed by me is there so near an ap-
proach to the formation of a true caudicle ; t and it is
curious that in this genus alone the pollen-grains
cohere in large packets, as in the Ophrese. If the
nascent caudicles had been attached to the lower ends
of the pollinia, and they are attached a little beneath
their summits, the pollinia would have been almost
identical with those of a true Orchis. In the rostellum
being supported by sloping sides, which wither when
the viscid disc is removed, — in the existence of a
membranous cup or clinandrum between the stigma

* 'Amer. Journal of Science,' bundle of elastic threads, with

vol. xxxiv. 1862, p. 427. I for- very small and thin packets of

merly thought that with this plant pollen-grains attached to them

and Spiranth^-s. it was the label- and arranged like tiles one over

lum which moved from the column the other. The two caudieles are

to allow of the more free entrance united together near their bases,

of insects ; but Professor Gray is where they are attached to a disc

convinced that it is the column of membrane lined with viscid

which moves. matter. From the small size and

t In a foreign species, Goodyera extreme thinness of the basal

discolor, sent me by Mr. Bateman, packets of pollen, and from the

the pollinia approach in structure strength of their attachment to

still more closely those of the the threads, I believe that they

OphreaB ; for the pollinia extend are in a functionless condition ;

into long caudicles, resembling in if so, these prolongations of the

form those of an Orchis. The pollinia are true caudicles.
caudicle is here formed of a

6

106 NEOTTE^. Chap. IV.

and anther, — and in some other respects, we have a
clear affinity with Spiranthes. In the anther having
a broad filament we see a relation to Cephalanthera.
In the structure of the rostellum, with the exception
of the sloping sides, and in the shape of the labellum,
Goodyera resembles Epipactis. Goodyera probably
shows us the state of the organs in a group of Orchids,
now mostly extinct, but the parents of many living
descendants.

Spiranthes autumnalis. — This Orchid with its pretty
name of Ladies'-tresses, presents some interesting
peculiarities.* The rostellum is a long, thin, flat pro-
jection, joined by sloping shoulders to the summit of
the stigma. In the middle of the rostellum a narrow
vertical brown object (fig. 17, C) may be seen, bordered
and covered by transparent membrane. This brown
object I will call "the boat-formed disc." It forms
the middle portion of the posterior surface of the
rostellum, and consists of a narrow strip of the exterior
membrane in a modified condition. When removed
from its attachment, its summit (fig. E) is seen to be
pointed, with the lower end rounded; it is slightly
bowed, so as altogether to resemble a boat or canoe.
It is rather more than -^ of an inch in length,
and less than -p^-g- in breadth. It is nearly rigid, and
appears fibrous, but is really formed of elongated
and thickened cells, partially confluent.

This boat, standing vertically up on its stern, is filled
with thick, milky, extremely adhesive fluid, which,
when exposed to the air, rapidly turns brown, and in
about one minute sets quite hard. An object is well
glued to the boat in four or five seconds, and when the

* I am indebted to Dr Bat tersby me specimens. I subsequently
of Torquay, and to Mr. A. (t. examined many growing plants.
More of Bembridge, for sending

Chap. IV.

SPIRANTHES AUTUMNALIS.

107

cement is dry the attachment is wonderfully strong.
The transparent sides of the rostellum consist of mem-
brane, attached behind to the edges of the boat, and
folded over in front, so as to form the anterior face
of the rostellum. This folded membrane, therefore,
covers, almost like a deck, the cargo of viscid matter
within the boat.

Fig. 17.

SPIRANTHES AUTUMNALIS, OR LADIES'-TrESSES.

a. anther.

p. pollen-masses.

t. threads of the pollen-masses.

cl. margin of clinandrum.

r. rostellum.

s. stigma.

n. nectar receptacle.

A. Side view of flower in its natural

position, with the two lower
sepals alone removed. The
label lum can be recognised by-
its fringed and reflexed lip.

B. Side view enlarged of a mature

flower, with all the sepals and
petals removed. The positions
of the labellum and of the

upper sepal are shown by the
dotted lines.

C. Front view of the stigma, and

of the rostellum with its em-
bedded, central, boat-formed
disc.

D. Front view of the stigma and of

the rostellum after the disc has
been removed.

E. Disc, removed from the rostel-

lum, greatly enlarged, viewed
posteriorly, with the attached
elastic threads of the pollen-
masses; the pollen-grains have
been removed from the threads,

The anterior face of the rostellum is slightly furrowed
in a longitudinal line over the middle of the boat, and

108 NEOTTE^. Chap. IV.

is endowed with a remarkable kind of irritability ;
for, if the furrow be touched very gently by a needle,
or if a bristle be laid along the furrow, it instantly
splits along its whole length, and a little milky
adhesive fluid exudes. This action is not mechanical,
or due to simple violence. The fissure runs up the
whole length of the rostellum, from the stigma beneath
to the summit : at the summit the fissure bifurcates,
and runs down the back of the rostellum on each side
and round the stern of the boat-formed disc. Hence
after this splitting action the boat-formed disc lies
quite free, but embedded in a fork in the rostellum.
The act of splitting apparently never takes place
spontaneously. I covered a plant with a net, and after
five of the flowers had fully expanded they were kept
protected for a week : I then examined their rostella,
and not one had split; whereas almost every flower
on the surrounding and uncovered spikes, which would
almost certainly have been visited and touched by
insects, had their rostella fissured, though they had
been open for only twenty-four hours. Exposure for
two minutes to the vapour of a little chloroform causes
the rostellum to split ; and this we shall hereafter see
is likewise the case with some other Orchids.

"When a bristle is laid for two or three seconds in the
furrow of the rostellum, and the membrane has con-
sequently become fissured, the viscid matter within
the boat-formed disc, which lies close to the surface
and indeed slightly exudes, is almost sure to glue the
disc longitudinally to the bristle, and both are with-
drawn together. When the disc, with the pollinia
attached to it, is withdrawn, the two sides of the ros-
tellum (fig. D), which have been described by some
botanists as two distinct foliaceous projections, are left
sticking up like a fork. This is the common con-

Chap. IV. SPIRANTHES AUTUMN ALIS. 109

dition of the flowers after they have been open for a
day or two, and have been visited by insects. The
fork soon withers.

Whilst the flower is in bud, the back of the boat-
formed disc is covered with a layer of large rounded
cells, so that the disc does not strictly form the exterior
surface of the back of the rostellum. These cells
contain slightly viscid matter : they remain unaltered
(as may be seen at fig. E) towards the upper end of
the disc, but at the point where the pollinia are at-
tached they disappear. Therefore I at one time con-
cluded that the viscid matter contained in these cells,
when they burst, serve to fasten the threads of the
pollinia to the disc ; but, as in several other genera,
in which a similar attachment has to be effected, I
could see no trace of such cells, this view may be
erroneous.

The stigma lies beneath the rostellum, and projects
with a sloping surface, as may be seen at B in the
side-view : its lower margin is rounded and fringed
with hairs. On each side a membrane (cl, B) extends
from the edges of the stigma to the filament of the
anther, thus forming a membranous cup or clinandrum,
in which the lower ends of the pollen-masses lie safely
protected.

Each pollinium consists of two leaves of pollen,
quite disconnected at their lower and upper ends, but
united for about half their length in the middle by
elastic threads. A very slight modification would
convert the two pollinia into four distinct masses, as
occurs in the genus Malaxis and in many foreign
Orchids. Each leaf consists of a double layer of
pollen-grains, joined by fours together, and these
united by elastic threads, which are more numerous
along the edges of the leaves, and converge at the

110 NEOTTE^J. Chap. IV.

summit of the pollinium. The leaves are very brittle,
and, when placed on the adhesive stigma, large pieces
are easily broken off.

Long before the flower expands, the anther-cells,
which are pressed against the back of the rostellum,
open in their upper part, so that the included pollinia
come into contact with the back of the boat-formed
disc. The projecting threads then become firmly
attached to rather above the middle part of the back
of the disc. The anther-cells afterwards open lower
down, and their membranous walls contract and be-
come brown ; so that by the time the flower is fully
expanded the upper part of the pollinia lie quite
naked, with their bases resting in a little cup formed
by the withered anther-cell, and laterally protected by
the clinandrum. As the pollinia thus lie loose, they
are easily removed.

The tubular flowers are elegantly arranged in a
spire round the spike, and project from it horizontally
(fig. A). The labellum is channelled down the middle,
and is furnished with a reflexed and fringed lip, on
which bees alight ; its basal internal angles are pro-
duced into two globular processes, which secrete an
abundance of nectar. The nectar is collected (n, fig.
B) in a small receptacle in the lower part of the
labellum. Owing to the protuberance of the inferior
margin of the stigma and of the two lateral inflexed
nectaries, the orifice into the nectar-receptacle is
much contracted. When the flower first opens the
receptacle contains nectar, and at this period the
front of the rostellum, which is slightly furrowed,
lies close to the channelled labellum ; consequently
a passage is left, but so narrow that only a fine bristle
can be passed down it. In a day or two the column
moves a little farther from the labellum, and a wider

Chap. IV. SPIRANTHES AUTUMN ALIS. Ill

passage is left for insects to deposit pollen on the
stigmatic surface. On this slight movement of the
column the fertilisation of the flower absolutely
depends.*

With most Orchids the flowers remain open for
some time before they are visited by insects ; but
with Spiranthes I have generally found the boat-
formed discs removed very soon after their expansion.
For example, in the two last spikes which I happened
to examine there were numerous buds on the summit
of one, with only the seven lowest flowers expanded,
of which six had their discs and pollinia removed;
the other spike had eight expanded flowers, and the
pollinia of all were removed. We have seen that when
the flowers first open they would be attractive to
insects, for the receptacle already contains nectar;
and at this period the rostellum lies so close to the
channelled labellum that a bee could not pass down
its proboscis without touching the medial furrow of
the rostellum. This I know to be the case by repeated
trials with a bristle.

We thus see how beautifully everything is contrived
that the pollinia should be withdrawn by insects visit-
ing the flowers. They are already attached to the
disc by their threads, and, from the early withering
of the anther-cells, they hang loosely suspended but
protected within the clinandrum. The touch of the

* Professor Asa Gray was so of all the parts in Spiranthes, with
kind as to examine fur me Spi- the exception that it is the column
ranthes gracilis and cernua in the and not the labellum, as I former-
United States. He found the ly thought, which moves as the
same general structure as in our flowers become mature. He adds
S. autumnalis, and was struck that the widening oi the passage,
with the narrowness of the passage which plays so important a part
into the flower. He has since in the fertilisation of the flower,
confirmed (* Amer. Journ. of "is so striking that we wonder
Science,' vol. xxxiv. p. 427) my how we overlooked it."
account of the structure and action

112 NEOTTE^J. Chap. IV.

proboscis causes the rostellum to split in front and
behind, and frees the long, narrow, boat-formed disc,
which is filled with extremely viscid matter, and is sure
to adhere longitudinally to the proboscis. When the
bee flies away, so surely will it carry away the pollinia.
As the pollinia are attached parallel to the disc, they
adhere parallel to the proboscis. When the flower
first opens and is best adapted for the removal of the
pollinia, the labellum lies so close to the rostellum,
that the pollinia attached to the proboscis of an insect
cannot possibly be forced into the passage so as to
reach the stigma ; they would be either upturned or
broken off : but we have seen that after two or three
days the column becomes more reflexed and moves
from the labellum, — a wider passage being thus left.
When I inserted the pollinia attached to a fine bristle
into the nectar-receptacle of a flower in this condition
(n, fig. B), it was pretty to see how surely the sheets
of pollen were left adhering to the viscid stigma. It
may be observed in the diagram, B, that owing to the
projection of the stigma, the orifice into the nectar-
receptacle (n) lies close to the lower side of the flower ;
insects would therefore insert their proboscides along
this lower side, and an open space above is thus left
for the attached pollinia to be carried down to the
stigma, without being brushed off. The stigma evi-
dently projects so that the ends of the pollinia may
strike against it.

Hence, in Spiranthes, a recently expanded flower,
which has its pollinia in the best state for removal,
cannot be fertilised ; and mature flowers will be ferti-
lised by pollen from younger flowers, borne, as we
shall presently see, on a separate plant. In con-
formity with this fact the stigmatic surfaces of the
older flowers are far more viscid than those of the

Crap. IV. SPIRANTHES AUTUMN ALIS. 113

younger flowers. Nevertheless, a flower which in its
early state had not been yisited by insects would not
necessarily, in its later and more expanded condition,
have its pollen wasted : for insects, in inserting and
withdrawing their proboscides, bow thern forwards or
upwards, and would thus often strike the furrow in the
rostellum. I imitated this action with a bristle, and
often succeeded in withdrawing the pollinia from old
flowers. I was led to make this trial from having at
first chosen old flowers for examination ; and on passing
a bristle, or fine culm of grass, straight down into
the nectary, the pollinia were never withdrawn ; but
when it was bowed forward, I succeeded. Flowers
which have not had their pollinia removed can be
fertilised as easily as those which have lost them ; and
I have seen not a few cases of flowers with their
pollinia still in place, with sheets of pollen on their
stigmas.

At Torquay I watched for about half an hour a
number of these flowers growing together, and saw
three humble-bees of two kinds visit them. I caught
one and examined its proboscis : on the superior
lamina, some little way from the tip, two perfect
pollinia were attached, and three other boat-formed
discs without pollen ; so that this bee had removed
the pollinia from five flowers, and had probably left
the pollen of three on the stigmas of other flowers.
The next day I watched the same flowers for a quarter
of an hour, and caught another humble-bee at work ;
one perfect pollinium and four boat-formed discs ad-
hered to its proboscis, one on the top of the other,
showing how exactly the same part of the rostellum
had each time been touched.

The bees always alighted at the bottom of the
spike, and, crawling spirally up it, sucked one flower

114 NEOTTE^. Chap. IV.

after the other. 1 believe humble-bees generally act
in this manner when visiting a dense spike of flowers,
as it is the most convenient method ; on the same
principle that a woodpecker always climbs up a tree in
search of insects. This seems an insignificant observa-
tion ; but see the result. In the early morning, when
the bee starts on her rounds, let us suppose that she
alighted on the summit of a spike ; she would cer-
tainly extract the pollinia from the uppermost and
last opened flowers ; but when visiting the next suc-
ceeding flower, of which the column in all probability
would not as yet have moved from the labellum (for
this is slowly and very gradually effected), the pollen-
masses would be brushed off her proboscis and wasted.
But nature suffers no such waste. The bee goes first
to the lowest flower, and, crawling spirally up the
spike, effects nothing on the first spike which she
visits till she reaches the upper flowers, and then she
withdraws the pollinia. She soon flies to another plant,
and, alighting on the lowest and oldest flower, into
which a wide passage will have been formed from the
greater reflexion of the column, the pollinia strike the
protuberant stigma. If the stigma of the lowest flower
has already been fully fertilised, little or no pollen
will be left on its dried surface ; but on the next
succeeding flower, of which the stigma is adhesive,
large sheets of pollen will be left. Then as soon as
the bee arrives near the summit of the spike she will
withdraw fresh pollinia, will fly to the lower flowers
on another plant, and fertilise them ; and thus, as she
goes her rounds and adds to her store of honey, she
continually fertilises fresh flowers and perpetuates the
race of our autumnal Spiranthes, which will yield
honey to future generations of bees.

Spiranthes australis. — This species, an inhabitant

Chap. IV. LISTERA OVATA. 115

of Australia, has been described and figured by Mr.
Fitzgerald.* The flowers are arranged on the spike
in the same manner as in S. autumnalis ; and the
labellum with two glands at its base closely resembles
that of our species. It is therefore an extraordinary
fact that Mr. Fitzgerald could not detect even in the
bud any trace of a rostellum or of viscid matter. He
states that the pollinia touch the upper edge of the
stigma, and fertilise it at an early age. Protecting a
plant from the access of insects by a bell-glass made
no difference in its fertility ; and Mr. Fitzgerald,
though he examined many flowers, never noticed the
slightest derangement of the pollinia, or any pollen
on the surfaces of the stigmas. Here then we have
a species which fertilises itself as regularly as does
Ojphrys apifera. It would, however, be desirable to
ascertain whether insects ever visit the flowers, which
it may be presumed secrete nectar, as glands are
present ; and any such insects should be examined, so
as to make certain that pollen does not adhere to some
part of their bodies.

Listera ovata, or Tway-llade. — This Orchid is one
of the most remarkable in the whole order. The
structure and action of the rostellum has been the
subject of a valuable paper in the * Philosophical
Transactions,' by Dr. Hooker,f who has described
minutely and of course correctly its curious structure ;
he did not, however, attend to the part which insects
play in the fertilisation of the flowers. C. K. Sprengel
well knew the importance of insect-agency, but he
misunderstood both the structure and the action of
the rostellum.

The rostellum is of large size, thin, or foliaceous,

* ' Australian Orchids,' part ii. t ' Philosophical Transactions,'

1876. 1854, p. 259.

116

NEOTTEjE.

Chai\ IV.

convex in front and concave behind, with its sharp
summit slightly hollowed out on each side ; it arches
over the stigmatic surface (fig. 18, A, r, s). Internally,

Fig. 18.

LiSTERA OVATA, or Tway-blade. (Partly copied from Hooker.)

col.

summit of co

umn.

A. Flower viewed laterally, with

a.

anther,
pollen.

all the sepals and petals, except
the labellum, removed.

r.

rostellum.

B. Ditto, with the pollinia re-

s.

stigma.

moved, and with the rostellum

1.

labellum.

bent down after the ejection

H.

nectar-secreti

ng

furrow.

of the viscid matter.

Chap. IV. LISTEBA OVATA. 117

it is divided by longitudinal septa into a series of
loculi, which contain viscid matter and have the power
of violently expelling it. These loculi show traces of
their original cellular structure. I have met with this
structure in no other genus except in the closely
allied Neottia. The anther, situated behind the ros-
tellum and protected by a broad expansion of the top
of the column, opens in the bud. When the flower is
fully expanded, the pollinia are left quite free, sup-
ported behind by the anther-cells, and lying in front
against the concave back of the rostellum, with their
upper pointed ends resting on its crest. Each pol-
linium is almost divided into two masses. The pollen-
grains are attached together in the usual manner by
a few elastic threads ; but the threads are weak, and
large masses of pollen can be broken off easily. After
the flower has long remained open, the pollen becomes
more friable. The labellum is much elongated, con-
tracted at its base, and bent downwards, as represented
in the drawing ; the upper half above the bifurcation
is furrowed along the middle ; and the borders of this
furrow secrete much nectar.

As soon as the flower opens, if the crest of the
rostellum be touched ever so lightly, a large drop
of viscid fluid is instantaneously expelled ; and this,
as Dr. Hooker has shown, is formed by the coalescence
of two drops proceeding from two depressed spaces on
each side of the centre. A good proof of this fact
was afforded by some specimens kept in weak spirits
of wine, which apparently had expelled the viscid
matter slowly, and here two separate little spherical
balls of hardened matter had been formed, attached to
the two pollinia. The fluid is at first slightly opaque
and milky; but on exposure to the air for less than
a second, a film forms over it, and in two or three

118 NEOTTEiE. Chap. IV.

seconds the whole drop sets hard, soon assuming a
purplish-brown tint. So exquisitely sensitive is the
rostellum, that a touch from the thinnest human hair
suffices to cause the explosion. It will take place
under water. Exposure to the vapour of chloroform
for about one minute also caused an explosion; but
the vapour of sulphuric ether did not thus act, though
one flower was exposed for fixe, and another for
twenty minutes to a strong dose. The rostellum of
these two flowers when afterwards touched exploded in
the usual manner, so that sensitiveness had not been
lost in either case. The viscid fluid when pressed
between two plates of glass before it has set hard is
seen to be structureless ; but it has a reticulated
appearance, perhaps caused by the presence of glo-
bules of a denser immersed in a thinner fluid. As the
pointed tips of the pollinia lie on the crest of the
rostellum, they are always caught by the exploded
drop : I have never seen this once to fail. So rapid
is the explosion and so viscid the fluid, that it is
difficult to touch the rostellum with a needle, however
quickly this may be done, without removing the
pollinia. Hence, if a bunch of flowers be carried
home in the hand, some of the sepals or petals will
almost certainly touch the rostellum and withdraw the
pollinia ; and this gives the false appearance of their
having been ejected to a distance.

After the anther-cells have opened and the naked
pollinia have been left resting on the concave back of
the rostellum, this latter organ curves a little forwards,
and perhaps the anther also moves a little backwards.
This movement is of much importance ; if it did not
occur, the tip of the anther, within which the pollinia
are lodged, would be caught by the exploded viscid
matter, and the pollinia would be for ever locked up

Chap. IV. LISTERA OVATA. 119

and rendered useless. I once found an injured flower
which had been pressed and had exploded before fully
expanding, and the anther with the enclosed pollen-
masses was permanently glued to the crest of the ros-
tellum. The rostellum, which is naturally somewhat
arched over the stigma, quickly bends forwards and
downwards at the moment of the explosion, so as then
to stand (fig. B) at right angles to the surface of the
stigma. The pollinia, if not removed by the touching
object which causes the explosion, become fixed to the
rostellum, and by its movement are likewise drawn a
little forward. If their lower ends are now freed by a
needle from the anther-cells, they spring up ; but they
are not by this movement placed on the stigma. In
the course of some hours, or of a day, the rostellum
not only slowly recovers its original slightly-arched
position, but becomes quite straight and parallel to
the stigmatic surface. This backward movement of
the rostellum is of service ; for if after the explosion it
had remained permanently projecting at right angles
over the stigma, pollen could not readily have been
deposited by insects on the viscid surface of the
stigma. When the rostellum is touched so quickly
that the pollinia are not removed, they are, as I have
just said, drawn a little forward ; but by the subse-
quent backward movement of the rostellum they are
pushed back again into their original position.

From the account now given we may safely infer
how the fertilisation of this Orchid is effected. Small
insects alight on the labellum for the sake of the
nectar copiously secreted by it ; as they lick this they
slowly crawl up its narrowed surface until their heads
stand directly beneath the overarching crest of the
rostellum ; when they raise their heads they touch the
crest ; this then explodes, and the pollinia are instantly

120 NEOTTE^J. Chap. IV.

and firmly cemented to their heads. As soon as the
insect flies away, it withdraws the pollinia, carries
them to another flower, and there leaves masses of the
friable pollen on the adhesive stigma.

In order to witness what I felt sure would take
place, I watched for an hour a group of plants on
three occasions ; each time I saw numerous speci-
mens of two small Hymenopterous insects, namely, a
Haemiteles and a Cryptus, flying about the plants and
licking up the nectar ; most of the flowers, which were
visited over and over again, already had their pollinia
removed, but at last I saw both these species crawl
into younger flowers, and suddenly retreat with a pair
of bright yellow pollinia sticking to their foreheads ; I
caught them, and found the point of attachment was to
the inner edge of the eye; on the other eye of one
specimen there was a ball of the hardened viscid
matter, showing that it had previously removed
another pair of pollinia, and in all probability had subse-
quently left them on the stigma of a flower. As these
insects were captured, I did not witness the act of fertili-
sation ; but Sprengel saw a Hymenopterous insect
leave its pollen-mass on the stigma. My son watched
another bed of this Orchid at some miles' distance, and
brought me home the same Hymenopterous insects
with attached pollinia, and he saw Diptera also
visiting the flowers. He was struck with the number
of spider-webs spread over these plants, as if the
spiders were aware how attractive the Listera was to
insects.

To show how delicate a touch suffices to cause
the rostellum to explode, I may mention that I found
an extremely minute Hymenopterous insect vainly
struggling to escape, with its head cemented by the
hardened viscid matter, to the crest of the rostellum

Chap. IV. LISTERA OVATA. 121

and to the tips of the pollinia. The insect was not
so large as one of the pollinia, and after causing the
explosion had not strength enough to remove them ;
it was thus punished for attempting a work beyond
its strength, and perished miserably.

In Spiranthes the young flowers, which have their
pollinia in the best state for removal, cannot possibly
be fertilised ; they must remain in a virgin condition
until they are a little older and the column has
moved away from the labellum. Here the same end
is gained by widely different means. The stigmas of
the older flowers are more adhesive than those of the
younger flowers. These latter have their pollinia
ready for removal ; but immediately after the rostellum
has exploded, it curls forwards and downwards, thus
protecting the stigma for a time ; but it slowly be-
comes straight again, and now the mature stigma is
left freely exposed, ready to be fertilised.

I wished to know whether the rostellum would
explode, if never touched ; but I have found it difficult
to ascertain this point, as the flowers are highly at-
tractive to insects, and it is scarcely possible to exclude
very minute ones, the touch of which suffices to cause
the explosion. Several plants were covered by a net
and left till the surrounding plants had set their
capsules ; and the rostella in most of the covered-up
flowers were found not to have exploded, though their
stigmas were withered, and the pollen mouldy and
incapable of removal. Some few of the very old
flowers, however, when roughly touched, were still
capable of a feeble explosion. Other flowers under
the nets had exploded, and they had the tips of their
pollinia fixed to the crest of the rostellum ; but whether
these had been touched by some minute insect, or had
exploded spontaneously, it was impossible to deter-

122

NEOTTE.E.

Chap. IV

nime.

It should be observed, that although I looked
carefully, not a grain of pollen could be found on the
stigmas of any of these flowers, and their ovaria had
not swollen. During a subsequent year, several plants
were again covered by a net, and I found that the
rostellum lost its power of explosion in about four
days ; the viscid matter having turned brown within
the loculi of the rostellum. The weather at the time
was unusually hot, and this probably hastened the
process. Aitei the four days the pollen had become
very incoherent, and some had fallen on the two
corners, and even over the whole surface of the stigma,
which was penetrated by the pollen-tubes. But the
scattering of the pollen was largely aided by, and
perhaps wholly depended on, the presence of Thrips
— insects so minute that they could not be excluded
by any net, and which abounded on the flowers. This
plant, therefore, is capable of occasional self-fertilisa-
tion, if the access of winged insects be prevented ; bat
I have every reason to believe that this occurs very
rarely in a state of nature.

That insects do their work of cross-fertilisation
effectually is shown by the following cases. The
seven upper flowers on a young spike with many
unexpanded buds, still retained their pollinia, but
these had been removed from the ten lower flowers ;
and there was pollen on the stigmas of six of them.
In two spikes taken together, the twenty-seven lower
flowers all had their pollinia removed, and had pollen
on their stigmas; these were succeeded by five open
flowers with the pollinia not removed and without any
pollen on the stigmas ; and these were succeeded by
eighteen buds. Lastly, in an older spike with forty-
four fully expanded flowers, the pollinia had been
removed from every single one ; and there was pollen,

Chap. IV. LISTERA OVATA. 123

generally in large quantity, on all the stigmas which
I examined.

I will recapitulate the several special adaptations
for the fertilisation of this plant. The anther-cells
open early, leaving the pollen-masses free, protected
by the summit of the column, and with their tips
resting on the concave crest of the rostellum. The
rostellum then slowly curves over the stigmatic
surface, so that its explosive crest stands at a little
distance from the summit of the anther; and this
is very necessary, otherwise the summit would be
caught by the viscid matter, and the pollen for ever
locked up. The curvature of the rostellum over the
stigma and over the base of the labellum is excellently
adapted to favour an insect striking the crest when it
raises its head, after having crawled up the labellum
and licked the last drop of nectar. The labellum, as
C. K. Sprengel has remarked, becomes narrower where
it joins the column beneath the rostellum, so that
there is no risk of an insect going too much to either
side. The crest of the rostellum is so exquisitely
sensitive, that a touch from a very minute insect
causes it to rupture at two points, and instantly two
drops of viscid fluid are expelled, which coalesce. This
viscid fluid sets hard in so wonderfully rapid a manner
that it rarely fails to cement the tips of the pollinia,
nicely laid on the crest of the rostellum, to the fore-
head of the touching insect. As soon as the rostellum
has exploded it suddenly curves downwards so as to
project at right angles over the stigma, protecting it
from impregnation at an early age, in the same manner
as the stigmas of the young flowers of Spiranthes are
protected by the labellum clasping the column. But
as the column of Spiranthes after a time moves from
the labellum, leaving a free passage for the introduc-

124 NEOTTE.E. Chap. IV.

tion of the pollinia, so here the rostellum moves back-
wards, and not only recovers its former arched position,
but stands upright, leaving the stigmatic surface, now
rendered more adhesive, perfectly free for pollen to be
left on it. The pollen-masses, when once cemented to
an insect's forehead, will remain attached to it, until
they are brought into contact with the stigma of a
mature flower ; and then these encumbrances will be
removed, by the rupturing of the weak elastic threads
which tie the grains together ; the flower being at the
same time fertilised.

Listera cordata. — Professor Dickie of Aberdeen was
so kind as to send me, but rather too late in the
season, two sets of specimens. The flowers have essen-
tially the same structure as in the last species. The
loculi of the rostellum are very distinct. Two or three
little hairy points project from the middle of the crest
of the rostellum ; but I do not know whether these
have any functional importance. The labellum has
two basal lobes (of which vestiges may be seen in
L. ovata) which curve up on each side ; and these
would compel an insect to approach the rostellum
straight in front. In two of the flowers the pollinia
were firmly cemented to the crest of the rostellum ;
but in almost all the others the pollinia had been
previously removed by insects.

In the following year Professor Dickie observed the
flowers on living plants, and he informs me that, when
the pollen is mature, the crest of the rostellum is
directed towards the labellum, and that, as soon as
touched, the viscid matter explodes, the pollinia becom-
ing attached to the touching object ; after the explosion,
the rostellum bends downwards, thus protecting the
virgin stigmatic surface ; subsequently it rises up and
exposes the stigma ; so that here everything goes on

Chap. IV. NEOTTIA NIDUS-AVIS. 125

as 1 have described under Listera ovata. The flowers
are frequented by minute Diptera and Hymenoptera.

Neottia nidus-avis. — I made numerous observations
on this plant, the Bird's-nest Orchis,* but they are not
worth giving, as the action and structure of every
part is almost identically the same as in Listera ovata
and cordata. On the crest of the rostellum there are
about six minute rough points, which seem particularly
sensitive to a touch, causing the expulsion of the
viscid matter. The exposure of the rostellum to the
vapour of sulphuric ether for twenty minutes did not
prevent this action, when it was touched. The label-
lum secretes plenty of nectar, which I mention merely
as a caution, because during one cold and wet season
I looked several times and could not see a drop, and
was perplexed at the apparent absence of any attrac-
tion for insects ; nevertheless, had I looked more per-
severingly, perhaps I should have found some.

The flowers must be freely visited by insects, for
all in one large spike had their pollinia removed.
Another unusually fine spike, sent me by Mr. Oxenden
from South Kent, had borne forty-one flowers, and it
produced twenty-seven large seed-capsules, besides
some smaller ones. Dr. H. Muller of Lippstadt in-
forms me that he has seen Diptera sucking the nectar
and removing the pollinia.

The pollen-masses resemble those of Listera, in
consisting of compound grains tied together by a few
weak threads ; they differ in being much more inco-
herent ; after a few days they swell and overhang the
sides and summit of the rostellum ; so that if the ros-
tellum of a rather old flower be touched and an explo-

* This unnatural sickly-looking lives ; but, according to Irmisch

plant has generally been supposed (' Beitrage zur Biologic und Mor-

to b> parasitic on the roots of the phologie der Orchideen,' 1853, s.

trees under the shade of which it 25), this certainly is not the case.

126 NEOTTE.E. Chap. IV.

sion caused, the pollen-masses are not so neatly caught
by their tips as those of Listera. Thus a good deal of
the friable pollen is often left behind in the anther-
cells and is apparently wasted. Several plants were
protected from the access of winged insects by a net,
and after four days the rostella had almost lost their
sensitiveness and power to explode. The pollen had
become extremely incoherent, and in all the flowers
much had fallen on the stigmas which were penetrated
by the pollen-tubes. The spreading of the pollen
seems to be in part caused by the presence of Thrips,
many of which minute insects were crawling about the
flowers, dusted all over with pollen. The covered-up
plants produced plenty of capsules, but many of these
were much smaller and contained fewer seeds than
those produced by the adjoining uncovered plants.

If insects had been forced by the labellum being
more upturned to brush against the anther and stigma,
they would always have been smeared with the pollen
as soon as it became friable ; and they would thus
have fertilised the flowers effectually without the aid
of the explosive rostellum. This conclusion interested
me, because, when previously examining Cephalan-
thera, with its aborted rostellum, its upturned label-
lum and friable pollen, I had speculated how a transi-
tion, with each gradation useful to the plant, could
have been effected from the state of the pollen in the
similarly constructed flowers of Epipactis, with their
pollinia attached to a well-developed rostellum, to the
present condition of Cephalanthera. Neottia nidus-
avis shows us how such a transition might have been
effected. This Orchid is at present mainly fertilised
by means of the explosive rostellum, which acts effec-
tually only as long as the pollen remains in mass;
but we have seen that as the flower grows old the
pollen swells and becomes friable, and is then apt to

Chap. IV. THELYMITRA. 127

fall or be transported by minute crawling insects on
to the stigma. By this means self-fertilisation is
assured, should larger insects fail to visit the flowers.
Moreover, the pollen in this state readily adheres to
any object ; so that by a slight change in the shape of
the flower, which is already less open or more tubular
than that of Listera, and by the pollen becoming
friable at a still earlier age, its fertilisation would be
rendered more and more easy without the aid of the
explosive rostellum. Ultimately it would become a
superfluity ; and then, on the principle that every part
which is not brought into action tends to disappear,
from causes which I have elsewhere endeavoured to
explain,* this would happen with the rostellum. We
should then see a new species, in the condition of
Cephalanthera as far as its means of fertilisation were
concerned, but in general structure closely allied to
Neottia and Listera.

Mr. Fitzgerald, in the introduction to his ' Austra-
lian Orchids,' says that Thelymitra carnea, one of
the Neotteae, invariably fertilises itself by means of the
incoherent pollen falling on the stigma. Nevertheless
a viscid rostellum, and other structures adapted for
cross-fertilisation are present. The flowers seldom
expand, and never until they have fertilised them-
selves ; so that they seem tending towards a cleisto-
gene condition. Thelymitra longifolia is likewise fer-
tilised in the bud, according to Mr. Fitzgerald, but
the flowers open for about an hour on fine days, and
thus cross-fertilisation is at least possible. On the
other hand, the species of the allied genus Diuris are
said to be wholly dependent on insects for their
fertilisation.

* * Variation of Animals and Plants under Domestication,' 2nd edit.
vol. ii. p. 309.

128

MALAXED.

Chap. V.

CHAPTER V.

MALAXEiE AND EPIDENDKEiE.

Malaxis paludosa— Masdevallia, curious closed flowers — Bolbophyllum,
labellum kept in constant movement by every breath of air — Dendro-
bium, contrivance for self-fertilisation — Cattleya, simple manner of
fertilisation — Epidendrum — Self-fertile Epidendrese.

I have now described the manner of fertilisation of
fifteen genera, found in Britain, which belong, accord-
ing to Lindley's classification, to the Ophreae, Arethu-
sese, and Neottese. A brief account of several foreign
genera belonging to these same tribes has been added,
from observations published since the appearance of
the first edition of this book. We will now turn to
the great exotic tribes of the Malaxeae, Epidendrese,
and Yandeae, which ornament in so wonderful a
manner the tropical forests. My chief object in
examining these latter forms has been to ascertain
whether their flowers were as a general rule fertilised
by pollen brought by insects from another plant. I
also wished to learn whether the pollinia underwent
those curious movements of depression by which, as
I had discovered, they are placed, after being removed
by insects, in the proper position for striking the
stigmatic surface.

By the kindness of many friends and strangers I
have been enabled to examine fresh flowers of several
species, belonging to at least fifty exotic genera, in
the several sub-tribes of the above three great tribes.*

* I am particularly indebted to Dr. Hooker, who on every occa-

Chap. V.

MALAXIS PALUDOSA.

129

It is not my intention to describe the means of fertili-
sation in all these genera, but merely to select a few
curious cases which illustrate the foregoing descrip-
tions. The diversity of the contrivances adapted to
favour the intercrossing of flowers, seems to be ex-
haustless.

MALAXED.

Malaxis paludosa. — This rare orchid* is the sole
representative of the tribe in this country, and it is
the smallest of all the British species. The labellum
is turned upwards,f instead of downwards, so that it
does not afford a landing-place for insects as in most
other Orchids. Its lower margin clasps the column,
making the entrance into the flower tubular. From

sion has given me his invaluable
advice, and has never become
weary of sending me specimens
from the Royal Gardens at Kew.

Mr. James Veitch, jun., has
generously given me many beau-
tiful Orchids, some of which were
of especial service. Mr. R. Parker
also sent me an extremely valu-
able series of forms. Lady Dorothy
Nevill most kindly placed her
magnificent collection of Orchids
at my disposal. Mr. Rucker of
West Hill, Wandsworth, sent me
repeatedly large spikes of Catase-
tum, a Morraodes of extreme value
and some Dendrobiums. Mr.
Rudgers of Sevenoaks has given
me interesting information. Mr.
Bateman, so well known for his
magnificent work on Orchids,
sent me a number of interesting
forms, including the wonderful
Angr&cum eesquipedale. I am
greatly indebted to Mr. Turnbull
of Down for allowing me the free
use of his hothouses, and for
giving me some interesting Or-
chids ; and to his gardener, Mr.

Horwood, for his aid in some of
my observations.

Professor Oliver has kindly
assisted me with his large stores
of knowledge, and has called my
attention to several papers. Lastly,
Dr. Lindley has sent me fresh
and dried specimens, and has in
the kindest manner helped me in
various ways.

To these gentlemen I can only
express my cordial thanks for
their unwearied and generous
kindness.

* I am greatly indebted to Mr.
Wallis, of Hartfield, in Sussex,
for numerous living specimens of
this Orchid.

t Sir James Smith, I believe,
first noticed this fact in the
1 English Flora,' vol. iv. p. 47,
1828. Towards the summit of
the spike the lower sepal does not
depend, as represented in the
woodcut (fig. 19, A), but projects
nearly at right angles. Nor are
the flowers always so completely
twisted round as here represented.

Fig. 19.

Malaxis paludosa.
(Partly copied from Bauer, but modified from living specimens.)

a. anther. v. spiral vessels.

p. pollen. r. rostellum.

cl. clinandrum. s. stigma.
I. labellum.

it. the sepal which in most orchids
stands on the upper side of the
flower.

A.. Perfect flower viewed laterally,
with the labellum in its natu-
ral position, upwards.

B. Column viewed in front, showing
the rostellum, the pocket-like
stigma, and the anterior late-
ral portions of the clinandrum.

C. Back view of the column in a

flower-bud, showing the anther
with the included pear-shaped
polliuia dimly seen, and the
posterior edges of the clinan-
drum.

D. Back view of an expanded flower,

with the anther now contracted
and shrivelled, exposing the
pollinia.

E. The two pollinia attached to a

little transverse mass of viscid
matter, hardened by spirits of
wine.

Chap. V. MALAXIS PALUDOSA. 131

its position it partially protects the organs of fructi-
fication (fig. 19). In most of the Orchidese, the upper
sepal and the two upper petals afford protection ; but
here these two petals and all the sepals are reflexed
(as may be seen in the drawing, fig. A), apparently to
allow insects freely to visit the flower. The position
of the labellum is the more remarkable, because it
has been purposely acquired, as shown by the ovarium
being spirally twisted. In all Orchids the labellum
is properly directed upwards, but assumes its usual
position on the lower side of the flower by the twist-
ing of the ovarium ; but in Malaxis the twisting has
been carried so far that the flower occupies the posi-
tion which it would have held if the ovarium had
not been at all twisted, and which the ripe ova-
rium afterwards assumes, by a process of gradual
untwisting.

When the minute flower is dissected, the column is
seen to be longitudinally tripartite; the middle
portion of the upper half (see fig. B) is the rostellum.
The upper edge of the lower part of the column
projects where united to the base of the rostellum,
and forms a rather deep fold. This fold is the stig-
matic cavity, and may be compared to a waistcoat-
pocket. I found pollen-masses which had their broad
ends pushed by insects into this pocket ; and a
bundle of pollen-tubes had here penetrated the
stigmatic tissue.

The rostellum, which stands immediately above the
stigmatic cavity, is a tall-membranous projection of a
whitish colour, formed of square cells, and is covered
with a thin layer of viscid matter : it is slightly con-
cave posteriorly, and its crest is surmounted by a
minute tongue-shaped mass of viscid matter. The
column, with its narrow pocket-like stigma and the

132 MALAXED. Chap. V.

rostellum above, is united on each side behind to a
green membranous expansion, convex exteriorly and
concave interiorly, of which the summits on each side
are pointed and stand a little above the crest of the
rostellum. These two membranes sweep round (see
back views, figs. C and D), and are united to the
filament or base of the anther ; they thus form a cup-
like clinandrum behind the rostellum. The use of this
cup is to protect laterally the pollen-masses. When
I have to treat of the homologies of the different parts,
it will be shown by the course of the spiral vessels
that these two membranes consist of the two upper
anthers of the inner whorl, in a rudimentary condition,
but utilised for this special purpose.

In a flower before it expands, a little mass or drop
of viscid fluid may be seen on the crest of the ros-
tellum, rather overhanging its front surface. After
the flower has remained open for a little time, this
drop shrinks and becomes more viscid. Its chemical
nature is different from that of the viscid matter in
most Orchids, for it remains fluid for many days,
though fully exposed to the air. From these facts
I concluded that the viscid fluid exuded from the
crest of the rostellum; but fortunately I examined
a closely-allied Indian form, namely, the Mierostylis
rhedii (sent me from Kew by Dr. Hooker), and in
this, before the flower opened, there was a similar drop
of viscid matter ; but on opening a still younger bud,
I found a minute, regular, tongue-shaped projection
on the crest of the rostellum, formed of cells, which
when slightly disturbed resolved themselves into a
drop of viscid matter. At this age, also, the front
surface of the whole rostellum, between its crest and
the pocket-like stigma, was coated with cells filled
with similar brown viscid matter ; so that there can

Vraf.Y. malaxis paludosa. 133

be little doubt, had I examined a young enough bud
of Malaxis, I should have found a similar minute
tongue-shaped cellular projection on the crest of the
rostellum.

The anther opens widely whilst the flower is in
bud, and then shrivels and contracts downwards, so
that, when the flower is fully expanded, the pollinia
are quite naked, with the exception of their broad
lower ends, which rest in two little cups formed by
the shrivelled anther-cells. This contraction of the
anther is represented in fig. D in comparison with fig.
C, which shows the state of the anther in a bud.
The upper and much pointed ends of the pollinia
rest on, but project beyond, the crest of the rostellum;
in the bud they are unattached, but by the time the
flower opens they are always caught by the posterior
surface of the drop of viscid matter, of which the
anterior surface projects slightly beyond the face of
the rostellum. That they are caught without any
mechanical aid I ascertained by allowing some buds
to open in my room. In fig. E the pollinia are shown
exactly as they appeared (but not quite in their
natural position) when removed by a needle from a
specimen kept in spirits of wine, in which the irre-
gular little mass of viscid matter had become hardened
and adhered firmly to their tips.

The pollinia consist of two pairs of very thin leaves
of waxy pollen ; and the four leaves are formed of
angular compound grains which never separate. As
the pollinia are almost loose, being retained merely by
the adhesion of their tips to the viscid fluid, and by
their bases resting in the shrivelled anther-cells, and
as the petals and sepals are much reflexed, the pollinia,
when the flower is fully expanded, would have been
liable to be blown away or out of their proper position,

134 MALAXED. Chap. V.

had it not been for the membranous expansions on
each side of the column forming the clinandrum,
within which they lie safely.

When an insect inserts its proboscis or head into
the narrow space between the upright labellum and
the rostellum, it will infallibly touch the little pro-
jecting viscid mass, and as soon as it flies away it
will withdraw the pollinia. I easily imitated this
action by inserting any small object into the tubular
flower between the labellum and rostellum. When
the insect visits another flower, the very thin pollen-
leaves attached parallel to the proboscis, or head, will
be forced into the pocket-like stigma with their broad
ends foremost. I found pollinia in this position glued
to the upper membranous expansion of the rostellum,
and with a large number of pollen-tubes penetrating
the stigmatic tissue. The use of the thin layer of
viscid matter, which coats the surface of the rostellum
in this genus and in Microstylis, and which is of no
use for the transportal of the pollen from flower to
flower, seems to be to keep the leaves of pollen fixed
in the narrow stigmatic cavity when their lower ends
have been inserted by insects. This fact is rather
interesting under a homological point of view, for, as
we shall hereafter see, the primordial nature of the
viscid matter of the rostellum is that which is common
to the stigmatic secretion of most flowers, namely, the
retention of the pollen, when placed by any means on
its stigma.

The flowers of the Malaxis, though so small and
inconspicuous, are highly attractive to insects. This
was shown by the pollinia having been removed from
all the flowers on the spikes which I examined,
excepting from one or two close under the buds. In
some old flower-spikes every single pollinium had

Chap.Y. pleurothallis pkolifera. 135

been carried away. Insects sometimes remove only
one of the two pairs. I noticed a flower with all four
pollen-leaves still in place, with a single one in the
stigmatic cavity; and this mnst clearly have been
brought by some insect. Within the stigmas of many
other flowers pollen-leaves were observed. The plant
produces plenty of seed ; and thirteen of the twenty-one
lower flowers on one spike had formed large capsules.

We will now turn to some exotic genera. The pol-
linia of Pleurothallis prolifera and ligulata (?) have a
minute caudicle, and mechanical aid is requisite to
force the viscid matter from the under side of the
rostellum into the anther, thus to catch the caudicles
and remove the pollinia. On the other hand, in our
British Malaxis and in Microstylis rhedii from India,
the upper surface of the minute tongue-shaped ros-
tellum becomes viscid and adheres to the pollinia
without any mechanical aid. This appears likewise to
be the case with Stelis racemiflora, but the flowers were
not in a good state for examination. * I mention this
latter flower partly because some insect in the hot-
house at Kew had removed most of the pollinia, and
had left some of them adhering to the lateral stigmas.
These curious little flowers are widely expanded and
much exposed ; but after a time the three sepals close
together with perfect exactness, so that it is scarcely
possible to distinguish an old flower from a bud : yet,
to my surprise, the closed flowers opened when im-
mersed in water.

The allied Masdevallia fenestrata bears an extra-
ordinary flower. The three sepals instead of closing,
as in the case of Stelis after the flower has remained
for a time expanded, cohere together and never open.
Two minute, lateral, oval windows (hence the name
fenestrata), are seated high up the flower opposite each

136

MALAXED.

Chap. V.

Fig. 20.

other, and afford the only entrance ; but the presence
of these two minute windows (fig. 20) shows how neces-
sary it is that insects should visit the flower in this
case as in that of most other Orchids. How insects
perform the act of fertilisation I have failed to under-
stand. At the bottom of the roomy and dark chamber
formed by the closed sepals, the minute column stands,
and in front of it is the furrowed labellum, with a
highly flexible hinge, and on each side the two upper
petals ; a little tube being thus formed. When there-
fore a minute insect enters, or
which is less probable, a larger in-
sect inserts its proboscis through
either window, it has to find by
the sense of touch the inner tube
in order to reach the nectary at
the base of the flower. Within
the little tube, formed by the
column, labellum, and lateral
petals, a broad and hinged rostel-
lum projects at right angles,
which can easily be upturned.
Its under surface is viscid, and
this viscid matter soon sets hard and dry. The minute
caudicles of the pollinia, projecting out of the anther-
case, rest on the base of the upper membranous surface
of the rostellum. The stigmatic cavity when mature
is not very deep. After cutting away the sepals I
vainly endeavoured, by pushing a bristle into the
tubular flower, to remove the pollinia, but by the aid
of a bent needle, this was effected without much
difficulty. The whole structure of the flower seems
as if intended to prevent the flower from being easily
fertilised ; and this proves that we do not understand
its structure. Some small insect had entered one of

MaSDEVALLIA FENES-
TRATA.

The window on the near side
is shown darkly shaded.

n. nectary.

Chap. V. BOLBOPHYLLUM. 137

the flowers in the hothouse at Kew, for many eggs
were deposited within it, near the base.

Of Bolbophyllum I examined the curious little
flowers of four species, which I will not attempt fully
to describe. In B. cupreum and cocoinum, the upper and
lower surfaces of the rostellum resolve themselves into
viscid matter, which has to be forced upwards by insects
into the anther, so as to secure the pollinia. I effected
this easily by passing a needle down the flower, which
is rendered tubular by the position of the labellum,
and then withdrawing it. In B. rhizopJiorse the anther-
case moves backwards, when the flower is mature,
leaving the two pollen-masses fully exposed, adhering
to the upper surface of the rostellum. They are held
together by viscid matter, and, judging from the
action of a bristle, are always removed together. The
stigmatic chamber is very deep with an oval orifice,
which exactly fits one of the two pollen-masses. After
the flower has remained open for some time, the sides
of the oval orifice close in and shut the stigmatic
chamber completely, — a fact which I have observed in
no other Orchid, and which, I presume, is here related
to the much exposed condition of the whole flower.
When the two pollinia were attached to a needle or
bristle, and were forced against the stigmatic chamber,
one of the two glided into the small orifice more readily
than could have been anticipated. Nevertheless, it is
evident that insects must place themselves on suc-
cessive visits to the flowers in precisely the same
position, so as first to remove the two pollinia, and
then force one of them into the stigmatic orifice. The
two upper filiform petals would serve as guides to
the insect ; but the labellum, instead of making the
flower tubular, hangs down just like a tongue out of a
widely open mouth.

138

MALAXED.

Chap. V.

The labellum in all the species which I have seen,
more especially in B. rhizophoree, is remarkable by
being joined to the base of the column by a very
narrow, thin, white strap, which is highly elastic and
flexible ; it is even highly elastic when stretched,
like an india-rubber band. When the flowers of this
species were blown by a breath of wind the tongue-like
labella all oscillated to and fro in a very odd manner.
In some species not seen by me, as in B. barbigerum,
the labellum is furnished with a beard of fine hairs,
and these are said to cause the labellum to be in
almost constant motion from the slightest breath of
air. What the use can be of this extreme flexibility
and liability to movement in the labellum, I cannot
conjecture, unless it be to attract the notice of insects,
as the flowers of these species are dull-coloured, small,
and inconspicuous, instead of being large, brightly-
coloured, and conspicuous or odoriferous, as in so many
other Orchids. The labella of some of the species are
said to be irritable, but I could not detect a trace of
this quality in those examined by me. According to
Lindley, the labellum of the allied Megaclinium falca-
tum spontaneously oscillates up and down.

The last genus of the Malaxeae which I will mention
is Dendrobium, of which one at least of the species,
namely D. chrysanthum, is interesting, from being
apparently contrived to effect its own fertilisation, if
an insect, when visiting the flower, should fail to
remove the pollen-masses. The rostellum has an
upper and a small lower surface composed of mem-
brane; and between these is a thick mass of milky-
white matter which can be easily forced out. This
white matter is less viscid than is usual ; but when
exposed to the air a film forms over it in less than
half a minute, and it soon sets into a waxy or cheesy

Chap. V.

DENDROBIUM CHRYSANTHUM.

139

substance. The large concave but shallow stigmatic
surface is seated beneath the rostellum. The pro-
duced anterior lip of the anther (see A) almost entirely
covers the upper surface of the rostellum. The fila-

Fig. 21.

DKNDROBIUM CHRYSANTHUM.

«. anther. s. stigma.

r. rostellum. I. labellum.

n. nectary.

A. Lateral view of flower, with the
anther in its proper position,
before the. ejection of the pol-
linia. All the sepals and petals
are removed except the label-
lum, which is longitudinally
bisected.

B. Outline of column, viewed later-
ally, after the anther has ejected
the pollinia.

0. Front view of column, showing
the empty cells of the anther,
after it has ejected its pollinia.
The anther is represented hang-
ing too low down, and covering
more of the stigma than it
really does.

ment of the anther is of considerable length, but is
hidden in the side view, A, behind the middle of the
anther; in the section, B, it is seen, after it has
sprung forward : it is elastic, and presses the anther
firmly down on the inclined surface of the clinan-

140

MALAXED

Chap. V.

drum (see fig. B) which lies behind the rostellum.
When the flower is expanded the two pollinia,
united into a single mass, lie quite loose on the
clinandrum and under the anther-case. The labellum
embraces the column, leaving a passage in front. The
middle portion of the labellum (as may be seen in
fig. A) is thickened, and extends up as far as the
top of the stigma. The lowest part of the column
is developed into a saucer-like nectary, which secretes
honey.

As an insect forces its way into one of these flowers,
the labellum, which is elastic, will yield, and the
projecting lip of the anther will protect the rostellum
from being disturbed ; but as soon as the insect
retreats, the lip of the anther will be lifted up, and
the viscid matter from the rostellum forced into the
anther, gluing the pollen-mass to the insect, which
will thus be transported to another flower. I easily
imitated this action ; but as the pollen-masses have
no caudicle and lie rather far back within the clinan-
drum beneath the anther, and as the matter from the
rostellum is not highly viscid, they were sometimes
left behind.

Owing to the inclination of the base of the clinan-
drum, and owing to the length and elasticity of the
filament, as soon as the anther is lifted up it always
springs forward, over the rostellum, and remains
hanging there with its lower empty surface (fig. C) sus-
pended over the summit of the stigma. The filament
now stretches across the space (see fig. B) which
was originally covered by the anther. Several times,
having cut off all the petals and labellum, and laid
the flower under the microscope, I raised the lip of the
anther with a needle, without disturbing the rostellum,
and saw the anther assume, with a spring, the position

Chap. V. DENDKOBIUM CHKYSANTHUM. 141

represented sideways in fig. B, and frontways in fig.
C. By this springing action the anther scoops the
pollinium ont of the concave clinandrum, and pitches
it up in the air, with exactly the right force so as to
fall down on the middle of the viscid stigma, where it
adheres.

Under nature, however, the action cannot be as thus
described, for the labellum hangs downwards ; and to
understand what follows, the drawing should be placed
in an almost reversed position. If an insect failed to
remove the pollinium by means of the viscid matter
from the rostellum, the pollinium would first be jerked
downwards on to the protuberant surface of the label-
lum, placed immediately beneath the stigma. But it
must be remembered that the labellum is elastic, and
that at the same instant that the insect, in the act of
leaving the flower, lifts up the lip of the anther, and
so causes the pollinium to be shot out, the labellum
will rebound back, and striking the pollinium will
pitch it upwards, so as to hit the adhesive stigma.
Twice I succeeded in effecting this by imitating the
retreat of an insect, with the flower held in its natural
position ; and on opening it, found the pollinium
glued to the stigma.

This view of the use of the elastic filament, seeing
how complicated the action must be, may appear
fanciful ; but we have seen so many and such curious
adaptations, that I cannot believe the strong elasticity
of the filament and the thickening of the middle part
of the labellum to be useless points of structure. If
the action be as I have described, we can perceive
their meaning, fur it would be an advantage to the
plant that its single large pollen-mass should not be
wasted, supposing that it failed to adhere to an insect
by means of the viscid matter from the rostellum.

142 EPIDENDEE^. Chap. V.

This contrivance is not common to all the species of
the genus ; for in neither D. higibbum nor D. formosum
was the filament of the anther elastic, nor was the
middle line of the labellum thickened. In D. tortile
the filament is elastic ; but as I examined only a
single flower, and before I had made out the structure
of D. chrysanthum, I cannot say how it acts.

Mr. Anderson states * that on one occasion the flowers
of his Dendrobium cretaceum did not expand, and yet
they produced capsules, one of which he sent me.
Almost all the numerous seeds in this capsule con-
tained embryos, thus differing greatly from the cases
presently to be given of the self-fertilised seeds from
the non-expanded flowers of a Cattleya. Mr. Anderson
remarks that Dendrobiums are the sole representatives
of the Malaxeae which, as far as he has seen, spon-
taneously form capsules. He likewise states that in
the immense group of the Vandese, hereafter to be
described, none of the species under his care, with
the exception of some belonging to the sub-division
of the Brassidse and of Sarcanthus parishii, has ever
spontaneously produced a capsule.

EPIDENDRE.E.

The Epidendreae and Malaxeae are characterised by
the pollen-grains cohering into large waxy masses.
In the latter of these groups the pollinia are said not
to be furnished with caudicles, but this is not uni-
versally the case, for they exist in Masdevallia fenes-
trate!, and some other species in an efficient condition,
although unattached and of minute size. In the
Epidendreae, on the other hand, free or unattached
caudicles are always present. For my purpose these

Journal of Horticulture,' 1863, pp. 206, 287.

Chap. V. CATTLEYA. 143

two great tribes might have been run together ; as the
distinction drawn from the presence of caudicles does
not always hold good. But difficulties of this nature
are frequently encountered in the classification of
largely developed or so-called natural groups, in which
there has been comparatively little extinction.

I will begin with the genus Cattleya, of which I
have examined several species. These are fertilised
in a very simple manner, different from that in any
British Orchid. The rostellum (r, fig. 22, A, B) is a
broad, tongue-shaped projection, which arches slightly
over the stigma ; the upper surface is formed of smooth
membrane ; the lower surface together with the central
portion (originally a mass of cells) consists of a very
thick layer of viscid matter. This viscid mass is
hardly separated from the viscid matter thickly coating
the stigmatic surface which lies close beneath the ros-
tellum. The projecting upper lip of the anther rests
on, and opens close over the base of the upper mem-
branous surface of the tongue-shaped rostellum. The
anther is kept closed by a spring, at its point of at-
tachment on the top of the column. The pollinia
consist of four (or eight in Cattleya crista) waxy
masses, each furnished (see figs. C and D) with a
ribbon-like tail, formed of a bundle of highly elastic
threads, to which numerous separate pollen-grains are
attached. The pollen therefore consists of two kinds,
namely, waxy masses and separate though compound
grains (each, as usual, consisting of four) united by
elastic threads. This latter kind of pollen is identical
with that of Epipactis and other Neottese.* These tails,
with their appended pollen-grains, act as caudicles,

* The pollen-masses of Bletia published by Lindley in Ms * II-
are admirably represented on a lustrations.'
large scale in Bauer's drawings,

144

EPIDENDEE.E.

Chap. V.

and are thus designated, for they serve as the means
for the removal of the larger waxy masses from the
anther-cells. The tips of the caudicles are generally
reflexed, and in the mature flower protrude a little

Fig. 22.

Cattleya.

a. anther.

6. spring at the top of the column.
p. pollen-masses.
r. rostellum.
s. stigma.
col. column.
/. label lum.
». nectary.
g. ovarium, or germen.
A. Front view of column, with all
the sepals and petals removed.

B. Section and lateral view of the

flower, with all the sepals and
petals removed, except the bi-
sected labellum shown only in
outline.

C. Anther viewed on the under side,

showing the four caudicles with
the four pollen-masses beneath.

D. A single pollinium, viewed later-

ally, showing the pollen-mass
and caudicle.

way out of the anther-case (see fig. A) lying on the
base of the upper membranous lip of the rostellum.
The labellum enfolds the column, making the flower

Chap. V. CATTLEYA. 145

tubular, and its lower part is produced into a nectary,
which penetrates the ovarium.

Now for the action of these parts. If any body of
size proportional to that of the tubular flower be
forced into it — a dead humble-bee acts very well — the
tongue-shaped rostellum is depressed, and the object
often gets slightly smeared with viscid matter ; but
in withdrawing it, the rostellum is upturned, and a
surprising quantity of viscid matter is forced over the
edges and sides, and at the same time into the lip of
the anther, which is also slightly raised by the up-
turning of the rostellum. Thus the protruding tips
of the caudicles are instantly glued to the retreating
object, and the pollinia are withdrawn. This hardly
ever failed to occur in my repeated trials. A living
bee or other large insect alighting on the fringed
edge of the labellum, and scrambling into the flower,
would depress the labellum and would be less likely
to disturb the rostellum, until it had sucked the
nectar and began to retreat. When a dead bee, with
the four waxy balls of pollen dangling by their
caudicles from its back, is forced into another flower,
some or all of them are caught with certainty by the
broad, shallow, and highly viscid stigmatic surface,
which likewise tears off the grains of pollen from the
threads of the caudicles.

That living humble-bees can thus remove the
pollinia is certain. Sir W. C. Trevelyan sent to Mr.
Smith of the British Museum a Bomhus hortorum,
which was forwarded to me — caught in his hothouse,
where a Cattleya was in flower — with its whole back,
between the wings, smeared with dried viscid matter,
and with the four pollinia attached to it by their
caudicles, ready to be caught by the stigma of any
other flower if the bee had entered one.

146 EPIDENDEE^. Chap. V

Those species which I have examined of Laelia,
Leptotes, Sophronitis, Barkeria, Phaius, Evelyna,
Bletia, Chysis, and Coelogyne, resemble Cattleya in
the caudicles of the pollinia being free, and in the
viscid matter from the rostellum not coming into
contact with them without mechanical aid, as well as
in their general manner of fertilisation. In Coelogyne
cristata the npper lip of the rostellum is much elon-
gated. In Evelyna carivata and Chysis eight balls of
waxy pollen are all united to a single caudicle. In
Barkeria the labellum, instead of enfolding the column,
is pressed against it, and this would effectually compel
insects to brush against the rostellum. In Epidendrum
we have a slight difference ; for the upper surface of
the rostellum, instead of permanently remaining mem-
branous, as in the above-named genera, is so tender
that by a touch it breaks up, together with the whole
lower surface, into a mass of viscid matter. In this
case the whole of the rostellum, together with the
adherent pollinia, must be removed by insects as they
retreat from the flower. I observed in E. glaucum that
viscid matter exuded from the upper surface of the
rostellum when touched, as happens with Epipactis.
In fact it is difficult to say, in these cases, whether
the upper surface of the rostellum should be called
membrane or viscid matter. With Chysis this matter
sets nearly hard and dry in twenty minutes, and
quite so in thirty minutes after its removal from the
rostellum.

In Epidendrum floribundum, there is a rather greater
difference : the anterior horns of the clinandrum (i. e.
the cup on the summit of the column in which the
pollinia lie) approach each other so closely as to
adhere to the two sides of the rostellum, which con-
sequently lies in a nick, with the pollinia seated over

Chap V. CATTLE YA. 147

it ; and as, in this species, the upper surface of the
rostellum resolves itself into viscid matter, the cau-
dicles of the pollinia become glued to it without any
mechanical aid. The pollinia, though thus attached,
cannot, of course, be removed from their anther-cells
without the aid of insects. In this species it seems
possible (though, from the position of parts, not
probable) that an insect might drag the pollinia out
and leave them on the stigma of the same flower. In
all the other species of Epidendrum which I examined,
and in all the above-mentioned genera, it is evident
that the viscid matter has to be forced upwards into
the lip of the anther by a retreating insect, which
would thus necessarily carry the pollinia from one
flower to the stigma of another.

Nevertheless, self-fertilisation takes place in some
Epidendrese. Dr. Cruger says * that " we have in
Trinidad three plants belonging to this family (a
Schomburgkia, Cattleya, and Epidendron) which rarely
open their flowers, and they are invariably found to be
impregnated when they do open them. In these cases
it is easily seen that the pollen-masses have been acted
on by the stigmatic fluid, and that the pollen-tubes
descend from the pollen-masses in situ down into the
ovarian canal." Mr. Anderson, a skilful cultivator of
Orchids in Scotland, also states that several of his
Epidendreae fertilise themselves spontaneously.! In
the case of Cattleya crista, the flowers sometimes do
not expand properly ; nevertheless they produce cap-
sules, one of which he sent to me. It contained an
abundance of seeds, but on examination I found that

* ' Journ. Linn. Soc. Bot.' vol. paper Mr. Gosse gives an account

viii. 1864, p. 131. of his microscopical examination

t 'Journal of Horticulture/ of the self-fertilised seeds.
1863, p. 206 and 287 : in the latter

148

EPIDENDBE.E.

Chap. V.

only about one per cent, contained an embryo. Similar
seeds were more carefully examined by Mr. Gosse, who
found that two per cent, contained an embryo. About
twenty-five per cent, of the seeds from a self-fertilised
capsule of Ldelia cinndbarina, also sent to me by
Mr. Anderson, were found to be good. It is therefore
doubtful whether the capsules spontaneously self-ferti-
lised in the West Indies, as described by Dr. Criiger,
were fully and properly fertilised. Fritz Muller in-
forms me that he has discovered in South Brazil
an Epidendrum which bears three pollen-producing
anthers, and this is a great anomaly in the order.
This species is very imperfectly fertilised by insects ;
but by means of the two lateral anthers the flowers
are regularly self-fertilised. Fritz Muller assigns good
reasons for his belief that the appearance of the two
additional anthers in this Epidendrum, is a case of
reversion to the primitive condition of the whole
group.*

See also ■ Bot. Zeitung/ 1869, p. 226, and 1870, p. 155*.

Chap. VI. STRUCTURE OF COLUMN. 149

CHAPTEK VI.

YANDEX.

Structure of the column and pollinia — Importance of the elasticity of
the pedicel ; its power of movement — Elasticity and strength of the
caudicles — Calanthe with lateral stigmas, manner of fertilisation —
Angrsecum sesquipedale, wonderful length of nectary — Species with
the entrance into the stigmatic chamber much contracted, so that
the pollen-masses can hardly be inserted— Coryanthes, extraordinary
manner of fertilisation.

We now come to the immense tribe of the Vandeae,
which includes many of the most magnificent produc-
tions of our hothouses, but like the Epidendreae has
no British representative. I have examined twenty-
nine genera. The pollen consists of waxy masses, as
in the two last tribes, and each ball of pollen is
furnished with a caudicle, which becomes, at an early
period of growth, united to the rostellum. The cau-
dicle is seldom attached directly to the viscid disc, as
in most of the Ophreae, but to the upper and posterior
surface of the rostellum ; and this part is removed by
insects, together with the disc and pollen-masses. The
sectional diagram (fig. 23), with the parts separated,
will best explain the type-structure of the Vandeae.
As in the rest of the Orchideae there are three con-
fluent pistils ; of these the dorsal one (2) forms the
rostellum arching over the two others (3) which unite
to form a single stigma. On the left hand we have
the filament (1) bearing the anther. The anther opens
at an early period, and the tips of the two caudicles
(but only one caudicle and one pollen-mass are re-

150

VANDE^.

Chap. VI.

presented in the diagram) protrude in a not fully-
hardened condition through a small slit, and adhere to
the back of the rostellum. The upper surface of the
rostellum is generally hollowed out for the reception
of the pollen-masses ; it is represented as smooth in
the diagram, but is really often furnished with crests

Fig. 23.

anther. caudicle
/

pollen.

filament
of anther.

pedicel of
rostellum.

viscid disc.

stigma.

12 3

Imaginary Section, illustrative of the structure of the column in the
Vande.e.

(1.) The filament, bearing the an-
ther with its pollen-masses ;
the anther is represented after
it has opened along its whole
under surface, so that the
section shows only the dorsal
surface.

(2.) The upper pistil, with the

upper part modified into the

rostellum.
(3.) The two lower confluent pistils,

bearing the two confluent

stigmas.

or knobs for the attachment of the two caudicles.
The anther afterwards opens more widely along its
under surface, and leaves the two pollen-masses un-
attached, excepting by their caudicles to the rostellum.
During an early period of growth, a remarkable
change has been going on in the rostellum : either its
extremity or its lower surface becomes excessively
viscid (forming the viscid disc), and a line of separa-

Chap. VI. STKUCTURE OF COLUMN. 151

tion, at first appearing as a zone of hyaline tissue, is
gradually formed, which sets free the disc, as well as
the whole upper surface of the rostellum, as far back
as the point of attachment of the caudicles. If any
object now touches the viscid disc, it, together with
the whole back of the rostellum, the caudicles and
pollen-masses, can all be readily removed together.
In botanical works the whole structure between the
disc or viscid surface (generally called the gland) and
the balls of pollen is designated as the caudicle ; but
as these parts play an essential part in the fertilisation
of the flower, and as they are fundamentally different
in their origin and in their minute structure, I shall
call the two elastic ropes, which are developed strictly
within the anther-cells, the caudicles ; and the portion
of the rostellum to which the caudicles are attached
(see diagram), and which is not viscid, the pedicel.
The viscid portion of the rostellum I shall call, as
heretofore, the viscid surface or disc. The whole may
be conveniently spoken of as the pollinium.

In the Ophreae we have (except in 0. pyramidalis
and a few other species) two separate viscid discs. In
the Vandeae, with the exception of Angraecum, we have
only one disc. The disc is naked, or is not enclosed
in a pouch. In Habenaria the discs, as we have seen,
are separated from the two caudicles by short drum-
like pedicels, answering to the single and generally
much more largely developed pedicel in the Vandeae.
In the Ophreae the caudicles of the pollinia, though
elastic, are rigid, and serve to place the packets of
pollen at the right distance from the insect's head or
proboscis, so as to reach the stigma. In the Vandeae
this end is gained by the pedicel of the rostellum.
The two caudicles in the Vandeae are embedded and
attached within a deep cleft in the pollen-masses,

152 VANDE^E. Chap. "VI.

and until stretched are rarely visible, for the pollen-
masses lie close to the pedicel of the rostellum. These
caudicles answer both in position and function to the
elastic threads, by which the packets of pollen are tied
together in the Ophreaa, at the point where they become
confluent ; for the function of the true caudicle in the
Vandeae is to break when the masses of pollen, trans-
ported by insects, adhere to the stigmatic surface.

In many Vandeae the caudicles are easily ruptured,
and the fertilisation of the flower, as far as this point
is concerned, is a simple affair ; but in other cases their
strength, and the length to which they can be stretched
before they break, are surprising. I was at first per-
plexed to understand what purpose these qualities
could serve. The explanation probably is that the
pollen-masses in this tribe are very precious objects ;
in most of the genera a flower produces only two, and
judging from the size of the stigma both are generally
left adhering to it. In other genera, however, the
orifice leading into the stigma is so small that probably
only one pollen-mass is left on it, and in this case the
pollen from one flower would suffice to fertilise two
flowers, but never a greater number. From the large
size of the flowers of many of the Yandeae, they no
doubt are fertilised by large insects, and these whilst
flying about would be likely to brush away and lose
the pollinia attached to them, unless the caudicles were
very strong and highly elastic. So again, when an
insect thus provided visited a flower either too young,
with its stigma not yet sufficiently adhesive, or one
already impregnated, with its stigma beginning to dry,
the strength of the caudicle would prevent the pollen-
masses from being uselessly removed and lost.

Although the stigmatic surface is astonishingly
adhesive at the proper period in many of these Orchids,

Chap. VI. SHAPE OF THE POLLINIA. 153

tor instance, in Phalaenopsis and Saccolabium, yet when
I inserted their pollinia attached to a rough object into
the stigmatic chamber, they did not adhere with suffi-
cient force to prevent their removal from the object. I
even left them for some little time in contact with the
adhesive surface, as an insect would do whilst feeding ;
but when I pulled the pollinia straight out of the
stigmatic chamber, the caudicles, though they were
stretched to a great length, did not rupture, nor did
their attachment to the object yield so that the balls
of pollen were withdrawn. It then occurred to me
that an insect in flying away would not pull the
pollinia straight out of the chamber, but would pull
at nearly right angles to its orifice. Accordingly I
imitated the action of a retreating insect, and dragged
the pollinia out of the stigmatic chamber at right
angles to its orifice; and now the friction on the
caudicles thus caused, together with the adhesiveness
of the stigmatic surface, generally sufficed to rupture
them; the pollen-masses being left on the stigma.
Thus, it seems that the great strength and extensi-
bility of the caudicles, which, until stretched, lie em-
bedded within the pollen-masses, serve to protect the
pollen-masses from being accidentally lost by an insect
whilst flying about, and yet, by friction being brought
into play, allow them at the proper time, to be left
adhering to the stigmatic surface ; the fertilisation of
the flower being thus safely effected.

The discs and pedicels of the pollinia present great
diversities in shape, and an apparently exhaustless
number of adaptations. Even in species of the same
genus, as in Oncidium, these parts differ greatly. I
here give a few figures (fig. 24), taken almost at hazard.
The pedicel generally consists, as far as I have seen,
of a thin ribbon-shaped membrane (fig. A) ; sometimes

154

VANDEiR.

Chap. VI.

it is almost cylindrical (fig. C) but often of the most
diversified shapes. The pedicel is generally nearly
straight, but in Miltonia clowesii it is naturally curved ;
and in some cases, as we shall immediately see, it
assumes, after removal, various shapes. The extensible
and elastic caudicles, by which the pollen-masses are
attached to the pedicel, are barely or not at all visible,
being embedded in a cleft or hollow within each
pollen-mass. The disc, which is viscid on the under
side, consists of a piece of thin or thick membrane of

Fig. 24.

POLLINIA OF VANDE^.

d. viscid disc.

ped. pedicel.

p. pollen-masses.

Tbe caudicles, being embedded within

the pollen-masses, are not shown.
A. Pollinium of Oncidium grande

after partial depression.

B. Pollinium oi Brassia maculata

(copied from Bauer).

C. Pollinium of Stanhopea saccata

after depression.

D. Pollinium of Sarcanthus tereti-

folius after depression.

varied forms. In Acropera it is like a pointed cap •
in some cases it is tongue-shaped, or heart-shaped
(fig. C), or saddle-shaped, as in some Maxillarias, or
like a thick cushion (fig. A), as in many species of
Oncidium, with the pedicel attached at one end, instead
of, as is more usual, nearly to the centre. In Angrsecum
distichum and sesquipedale the rostellum is notched,
and two separate, thin, membranous discs can be
removed, each carrying by a short pedicel a pollen-
mass. In Sarcanthus teretifolius the disc (fig. D) is

Chap. VI. MOVEMENTS OF THE POLLINIA. 155

very oddly shaped; and as the stigmatic chamber
is deep and likewise curiously shaped, we are led to
believe that the disc is fastened with great precision
to the square projecting head of some insect.*

In most cases there is a plain relation between the
length of the pedicel and the depth of the stigmatic
chamber, into which the pollen-masses have to be
inserted. In some few cases, however, in which a long
pedicel and a shallow stigma co-exist, we shall presently
meet with curious compensating actions. After the
disc and pedicel have been removed, the shape of the
remaining part of the rostellum is of course altered,
being now slightly shorter and thinner, and sometimes
notched. In Stanhopea, the entire circumference of
the extremity of the rostellum is removed, and a thin,
pointed, needle-like process alone is left, which origin-
ally ran up the centre of the disc.

If we now turn to the diagram (fig. 23, p. 150), and
suppose the rectangularly bent rostellum to be thinner
and the stigma to lie closer beneath it than is there
represented, we shall see that, if an insect with a polli-
nium attached to its head were to fly to another flower
and occupy exactly the same position which it held
whilst the attachment was effected, the pollen-masses
would be in the right position for striking the stigma,
especially if, from their weight, they were to become
in the least degree depressed. This is all that takes
place in Ly caste shinnerii, Cymbidium giganteum,
Zygopetalum machai, Angr tecum, eburneum, Miltonia
elowesii, in a Warrea, and, I believe, in Galeandra
funhii. But if in our diagram we suppose, for instance,

* I may here remark that Del- dium, Epidendrum, Phaius, and

pino (' Fecondazione nelle Piante/ Dendrobium, and is able to con-

Firenze, 1867, p. 19) says he has firm in general my statements,
examined flowers of Vanda, Onci-

156 VANDE^l. Chap. VL

the stigma to be seated at the bottom of a deep cavity,
low down in the column, or the anther to be seated
higher up, or the pedicel of the rostellum to slope
more upwards, &c. — all of which contingencies occur
in various species, — in such cases, an insect with a
pollinium attached to its head, if it flew to another
flower, would not place the pollen-masses on the
stigma, unless their position had become greatly
changed after attachment.

This change is effected in many Vandese in the same
manner as is so general with the Ophreae, namely, by a
movement of depression in the pollinium in the course
of about half a minute after its removal from the
rostellum. I have seen this movement conspicuously
displayed, generally causing the pollinium to rotate
through about a quarter of a circle, in several species
of Oncidium, Odontoglossum, Brassia, Vanda, Aerides,
Sarcanthus, Saccolabium, Acropera, and Maxillaria.
In Bodriguezia suaveolens the movement of depression
is remarkable from its extreme slowness ; in Eulophia
viridis from its small extent. Mr. Charles Wright, in
a letter to Professor Asa Gray, says that he observed
in Cuba a pollinium of an Oncidium attached to a
humble-bee, and he concluded at first that I was
completely mistaken about the movement of depres-
sion ; but after several hours it moved into the proper
position for fertilising the flower. In some of the
cases above specified in which the pollinia apparently
undergo no movement of depression, I am not sure that
there was not a very slight one after a time. In the
various Ophreae the anther-cells are sometimes seated
exteriorly and sometimes interiorly with respect to
the stigma ; and there are corresponding outward and
inward movements in the pollinia : but in the Vandese
the anther-cells always lie, as far as I have seen,

Chap. VI. MOVEMENTS OF THE POLLINIA. 157

directly over the stigma, and the movement of the
pollinium is always directly downwards. In Calanthe,
however, the two stigmas are placed exteriorly to the
anther-cells, and the pollinia, as we shall see, are made
to strike them by a peculiar mechanical arrangement
of the parts.

In the OphresB the seat of contraction, which causes
the act of depression, is in the upper surface of the
viscid disc, close to the point of attachment of the
caudicles : in most of the Vandeae the seat is likewise
in the upper surface of the disc, but at the point
where the pedicel is united to it, and therefore at a
considerable distance from the point of attachment of
the true caudicles. The contraction is hygrometric, but
to this subject I shall return in the ninth chapter ;
therefore the movement does not take place until the
pollinium has been removed from the rostellum, and
the point of union between the disc and pedicel has
been exposed for a few seconds or minutes to the air.
If, after the contraction and consequent movement of
the pedicel, the whole body be placed into water, the
pedicel slowly moves back and resumes its former
position with respect to the viscid disc. When taken
out of water, it again undergoes the movement of de-
pression. It is of importance to notice these facts, as
we thus get a test by which this movement can be
distinguished from certain other movements.

In Maxdlaria orniihorhyncha> we have a unique case.
The pedicel of the rostellum is much elongated, and
is entirely covered by the produced front lip of the
anther, and is thus kept damp. When removed it
bends quickly backwards on itself, at about its central
point, and thus becomes only half as long as it was
before. When placed in water it resumes its original
straight form. If the pedicel had not been in some

158 VANDE^]. Chap. VI.

manner shortened, it is hardly possible that the flower
could have been fertilised. After this movement, the
pollinium attached to any small object can be inserted
into the fiWer, and the balls of pollen readily adhere
to the stigmatic surface. Here we have an instance
of one of those compensating actions in the pollinia,
before alluded to, in relation to the shallowness of
the stigma.

In some cases, besides hygrometric movements,
elasticity comes into play. In Aerides odorata and
virens, and in an Oncidium (roseum ?), the pedicel of
the rostellum is fastened down in a straight line, at
one extremity by the disc, and at the other by the
anther ; it has, however, a strong elastic tendency to
spring up at right angles to the disc. Consequently,
if the pollinium, attached by its viscid disc to some
object, is removed from the anther, the pedicel instantly
springs up and stands at nearly right angles to its
former position, with the pollen-masses carried aloft.
This has been noticed by other observers ; and I agree
with them that the object gained is to free the pollen-
masses from the anther-cells. After this upward elastic
spring, the downward hygrometric movement imme-
diately commences, which, oddly enough, carries the
pedicel back again into almost exactly the same
position, relatively to the disc, which it held whilst
forming part of the rostellum. In Aerides the end of
the pedicel, to which the pollen-masses are attached
by short dangling caudicles, after springing up, remains
a little curved upwards ; and this curvature seems
well adapted to drop the pollen-masses into the deep
stigmatic cavity over the ledge in front. The differ-
ence between the first elastic and the second or re-
versed hygrometric movement, was well shown by
placing the pollinium of the above Oncidium into

Chap. VI. MOVEMENTS OF THE POLLINIA. 159

water, after both movements had taken place ; and
the pedicel then moved into the same position which
it had at first assumed through its elasticity ; this
movement not being in any way affected by the
water. When taken out of water the hygrometric
movement of depression soon commenced for the
second time.

In Ilodriguezia secunda there was no hygrometric
movement of depression in the pedicel as in the before-
mentioned B. suaveolens, but there was a rapid down-
ward movement, due to elasticity, and of this I have
seen no other instance ; for when the pedicel was put
into water it showed no tendency to recover its original
position, as occurred in many other cases.

In Phdlsenopsis grandiflora and amdbilis the stigma
is shallow and the pedicel of the rostellum long.
Some compensating action is therefore requisite, which,
differently from that in Maxillaria ornitliorhyncha is
effected by elasticity. There is no movement of de-
pression ; but, when the pollinium is removed, the
straight pedicel suddenly curls up in the middle, thus
( — ^— ■ ) : the full-stop on the left hand may re-
present the balls of pollen, and the thick hyphen to
the right may be supposed to represent the triangu-
larly shaped disc. The pedicel does not straighten
itself when placed in water. The end carrying the
balls of pollen is a little raised up after this elastic
movement, and the pedicel, with one end raised, and
with the middle part upwardly bowed, is well adapted
to drop the pollen-masses into the deep stigmatic
cavity, over a ledge in front. Fritz Muller informs
me of a case in which the shortening of a very long
pedicel is effected partly by elasticity and partly by a
hygrometric movement. A small Ornithocephalus,
growing in South Brazil, has a very long pedicel,

160

YANDEX.

Chap. IV.

which is shown closely attached to the rostellum in
the accompanying figure A.

Fig. 25.

Pollinium OF Ornithocephalus. (From a sketch by Fritz Miiller.)

A. Pollinium still attached to the

rostellum with the pollen-
mass still lying in the cli-
nandrum on the summit of
the column.

B. Pollinium in the position which

it first assumes from the elas-
ticity of the pedicel.
Pollinium in the position ul-
timately assumed from the
hygrometric movement.

The pedicel when freed suddenly bends into the
form represented at B, and soon afterwards owing to
the hygrometric contraction curls up into the odd
figure shown at C. When placed in water it resumes
the form represented at B.

CHAr. VI.

CALANTHE MASUCA.

161

In Calanthe masuca and the hybrid G. dominii the
structure is very different to what it is in most other
Vandea?. We here have two oval, pit-like stigmas
on each side of the rostellum (fig. 26). The viscid
disc is oval (fig. B), and has no pedicel, but eight
masses of pollen are attached to it by very short and

Fig. 26.

A C

Calanthe masuca.

p. pol leu-masses.

s s. the two stigmas.

In. mouth of nectary,
labellum.

d. viscid disc.

cl. in fig. C, clinandrum the pol-
len-masses being removed.

A. Flower viewed from above, with
the anther -case removed,
showing the eight pollen-
masses in their proper position
within the clinandrum. All
the sepals and petals have been
cut away except the labellum.

B. Pollen-masses attached to the

viscid disc, seen from the
under side.

C. Flower in same position as in A,

but with the disc and pollen-
masses removed, and now
showing the deeply notched
rostellumand the empty clin-
andrum in which the pollen
masses lay. Within the left-
hand stigma two pollen-
masses may be seen adhering
to its viscid surface.

easily ruptured caudicles. These pollen-masses radiate
from the disc like the leaves of a fan. The rostellum
is broad, and its sides slope on each side towards the
lateral pit-like stigmas. When the disc is removed
the rostellum is seen (fig. C) to be deeply notched
in the middle. The labellum is united to the column
almost up to its summit, leaving a passage (n, A) to

162 VANDE^E. Chap. VI

the long nectary close beneath the rostellum. The
labellum is studded with singular, wartlike, globular
excrescences.

If a thick needle be inserted into the mouth of the
nectary (fig. A), and then withdrawn, the viscid disc
is removed, bearing with it the elegant fan of radiating
pollen-masses. These undergo no change in position.
But if the needle be now inserted into the nectary of
another flower, the ends of the pollen-masses neces-
sarily hit the upper and laterally sloping sides of the
rostellum, and, glancing off both ways, strike down
into the two lateral pit-like stigmas. The thin cau-
dicles being easily ruptured, the pollen-masses are left
adhering like little darts to the viscid surface of both
stigmas (see left-hand stigma in fig. C), and the fertili-
sation of the flower is completed in a simple manner
pleasing to behold.

I should have stated that a narrow transverse rim of
stigmatic tissue, beneath the rostellum, connects the
two lateral stigmas ; and it is probable that some of
the middle pollen-masses may be inserted through the
notch in the rostellum, so as to adhere to this rim.
I am the more inclined to this opinion from having
found in the elegant Calanthe vestita the rostellum
extending so widely over the two lateral stigmas, that
apparently all the pollen-masses must be inserted
beneath its surface.

The Angrmcum sesquipedale, of which the large six-
rayed flowers, like stars formed of snow-white wax,
have excited the admiration of travellers in Madagascar,
must not be passed over. A green, whip-like nectary
of astonishing length hangs down beneath the label-
lum. In several flowers sent me by Mr. Bateman I
found the nectaries eleven and a half inches long, with
only the lower inch and a half filled with nectar.

Chap. VI. ANGR^ECUM SESQUIPEDALE. 163

What can be the use, it may be asked, of a nectary of
such disproportionate length ? We shall, I think, see
that the fertilisation of the plant depends on this
length, and on nectar being contained only within the
lower and attenuated extremity. It is, however, sur-
prising that any insect should be able to reach the
nectar. Our English sphinxes have proboscides as long
as their bodies ; but in Madagascar there must be
moths with proboscides capable of extension to a length
of between ten and eleven inches! This belief of
mine has been ridiculed by some entomologists, but we
now know from Fritz Muller * that there is a sphinx-
moth in South Brazil which has a proboscis of nearly
sufficient length, for when dried it was between ten
and eleven inches long. When not protruded it is
coiled up into a spiral of at least twenty windings.

The rostellum is broad and foliaceous, and arches
rectangularly over the stigma and over the orifice of
the nectary : it is deeply notched by a cleft enlarged
or widened at the inner end. Hence the rostellum
nearly resembles that of Calanthe after the disc has
been removed (see fig. 26, C). The under surfaces of
both margins of the cleft, near their ends, are bordered
by narrow strips of viscid membrane, easily removed ;
so that there are two distinct viscid discs. A short
membranous pedicel is attached to the middle of the
upper surface of each disc ; and the pedicel carries a
pollen-mass at its other end. Beneath the rostellum
a narrow, ledge-like, adhesive stigma is seated.

I could not for some time understand how the
pollinia of this Orchid were removed, or how the
stigma was fertilised. I passed bristles and needles

* See letter with a drawing by Hermann Muller, 'Nature,' 1873,
p. 223.

164 TANDEM. Chap. VI.

down the open entrance into the nectary and through
the cleft in the rostellum with no result. It then
occurred to me that, from the length of the nectary,
the flower must be visited by large moths, with a
proboscis thick at the base ; and that to drain the last
drop of nectar, even the largest moth would have to
force its proboscis as far down as possible. Whether
or not the moth first inserted its proboscis by the open
entrance into the nectary, as is most probable from the
shape of the flower, or through the cleft in the ros-
tellum, it would ultimately be forced in order to drain
the nectary to push its proboscis through the cleft,
for this is the straightest course ; and by slight pressure
the whole foliaceous rostellum is depressed. The dis-
tance from the outside of the flower to the extremity of
the nectary can be thus shortened by about a quarter
of an inch: I therefore took a cylindrical rod one-
tenth of an inch in diameter, and pushed it down
through the cleft in the rostellum. The margins
readily separated, and were pushed downwards together
with the whole rostellum. When I slowly withdrew the
cylinder the rostellum rose from its elasticity , and
the margins of the cleft were upturned so as to clasp
the cylinder. Thus the viseid strips of membrane on
each under side of the cleft rostellum came into contact
with the cylinder, and firmly adhered to it ; and the
pollen-masses were withdrawn. By this means I suc-
ceeded every time in withdrawing the pollinia ; and
it cannot, I think, be doubted that a large moth would
thus act; that is, it would drive its proboscis up to
the very base through the cleft of the rostellum, so as
to reach the extremity of the nectary ; and then the
pollinia attached to the base of its proboscis would be
safely withdrawn.

I did not succeed in leaving the pollen-masses on

Chap. VI. ANGR^CUM SESQUIPEDALE. 165

the stigma so well as I did in withdrawing them. As
the margins of the cleft rostellum must be upturned
before the discs adhere to a cylindrical body, during
its withdrawal, the pollen -masses become affixed some
little way from its base. The two discs did not always
adhere at exactly opposite points. Now, when a moth
with the pollinia adhering to the base of its proboscis,
inserts it for a second time into the nectary, and exerts
all its force so as to push down the rostellum as far as
possible, the pollen-masses will generally rest on and
adhere to the narrow, ledge-like stigma which projects
beneath the rostellum. By acting in this manner with
the pollinia attached to a cylindrical object, the pollen-
masses were twice torn off and left glued to the stig-
matic surface.

If the Angraecum in its native forests secretes more
nectar than did the vigorous plants sent me by Mr.
Bateman, so that the nectary ever becomes filled, small
moths might obtain their share, but they would not
benefit the plant. The pollinia would not be with-
drawn until some huge moth, with a wonderfully long
proboscis, tried to drain the last drop.* If such great
moths were to become extinct in Madagascar, assur-
edly the Angraecum would become extinct. On the
other hand, as the nectar, at least in the lower part
of the nectary, is stored safe from the depredation of
other insects, the extinction of the Angraecum would
probably be a serious loss to these moths. We can
thus understand how the astonishing length of the

* Mr. Belt suggests (' The Na- ment can thus be accounted for.

turalist in Nicaragua,' 1874, p. I have no doubt of the truth of

133) that the great length of the this principle, but it is hardly

nectary of this plant serves to applicable here, as the moth has

prevent other moths which are to be compelled to drive its pro-

not well-adapted for the fertilisa- boscis as deeply down as possible

tion of the flowers from sucking into the flower,
the nectar, and that its develop-

166 VANDE.E. Chap. VI.

nectary had been acquired by successive modifications.
As certain moths of Madagascar became larger through
natural selection in relation to their general conditions
of life, either in the larval or mature state, or as the
proboscis alone was lengthened to obtain honey from
the Angraecum and other deep tubular flowers, those
individual plants of the Angraecum which had the
longest nectaries (and the nectary varies much in
length in some Orchids), and which, consequently,
compelled the moths to insert their proboscides up to
the very base, would be best fertilised. These plants
would yield most seed, and the seedlings would
generally inherit long nectaries; and so it would be
in successive generations of the plant and of the moth.
Thus it would appear that there has been a race in
gaining length between the nectary of the Angraecum
and the proboscis of certain moths ; but the Angraecum
has triumphed, for it flourishes and abounds in the
forests of Madagascar, and still troubles each moth
to insert its proboscis as deeply as possible in order to
drain the last drop of nectar.

I could add descriptions of many other curious
structures in the Vandeae, more especially from the
letters of Fritz Miiller with respect to those of Brazil ;
but the reader would be wearied. I must, however,
make a few remarks on certain genera, the fertilisation
of which remains a mystery, chiefly on account of the
narrowness of the mouth of the stigma, as this renders
the insertion of the pollen-masses extremely difficult.
Two closely allied species or varieties of Acropera, viz.,
A. luteola and loddigesii have been observed by me
during several seasons, and every detail of their struc-
ture seems as if specially adapted to render their
fertilisation almost impossible. I have met with hardly

Cuai'.VI. ACROPERA, AND SOME ALLIED GENERA. 167

any other such case, not that I fully understand the
contrivances in any Orchid, for new and admirable
ones become apparent, the longer I study even one of
our commonest British species.

The thin and elongated rostellum of Acropera projects
at right angles to the column (see diagram, fig. 23, p.
150) ; and the pedicel of the pollinium is of course
equally long and much thinner. The disc consists of
an extremely small cap, viscid within, which fits on
the extremity of the rostellum. The viscid matter
sets hard but slowly. The upper sepal forms a hood
enclosing and protecting the column. The labellum
is an extraordinary organ, baffling all description : it
is articulated to the column by a thin strap, so elastic
and flexible that a breath of wind sets it vibrating.
It hangs downwards ; and the retention of this posi-
tion seems to be of importance, for the footstalk (ova-
rium) of each flower is curved into a semicircle, so
as to compensate for the pendulous habit of the plant.
The two upper petals and the lateral lobes of the
labellum serve as guides leading into the hood-like
upper sepal.

The pollinium, when adhering by its disc to an
object, undergoes the common movement of depression ;
and this seems superfluous, for the stigmatic cavity lies
(see diagram, fig. 23) high up at the base of the rect-
angularly projecting rostellum. But this is a com-
paratively trifling difficulty ; the real difficulty lies in
the orifice of the stigmatic chamber being so narrow
that the pollen-masses, though consisting of thin sheets,
can hardly be forced in. I repeatedly tried, and suc-
ceeded only three or four times. Even after leaving
them to dry for four hours before a fire, and thus to
shrink a little, I rarely succeeded in forcing them
into the stigma. I examined quite young flowers and

168 VANDE.E. Chap. VI.

almost withered ones, for I imagined that the mouth
of the chamber might be of larger size at some period
of growth ; but the difficulty of insertion remained
the same. Now when we observe that the viscid disc
is extraordinarily small, and consequently its power of
attachment not so firm as with Orchids having a large
disc, and that the pedicel is very long and thin, it
would seem almost indispensable that the stigmatic
chamber should be unusually large for the easy
insertion of the pollinium, instead of being much con-
tracted. Moreover, the stigmatic surface, as Dr. Hooker
has likewise observed, is singularly little adhesive !

The flowers when ready for fertilisation do not
secrete nectar ; * but this is no difficulty, for as Dr.
Criiger has seen humble-bees gnawing the projections
on the labellum of the closely allied Gongora maculata,
there can be little doubt that the distal cup-shaped
part of the labellum of Acropera offers a similar at-
traction to insects. After numberless trials in many
ways, I have found that the pollinia can be removed
with certainty only by pushing the rostellum a little
upwards with a camel-hair brush, held in such a
position that the tip slides along the under side of the
rostellum, so as to brush off the little viscid cap on its
extremity, into which the hairs enter and are glued
fast. I further find that if the brush with a pollinium
thus attached to its tip is pushed into and then with-
drawn from the stigmatic cavity, the mouth of which
is furnished with a sharp ridge, the end of the pedicel

* Mr. Scott 1 as observed that at no other time could he find a

after the flowers of Acropera and trace of nectar. This exudation

of two species in the allied genus can, therefore, be of no use to the

of Gongora have been fertilised, plant with respect to its fertili-

an abundance of nectar exudes sation, and must be viewed as an

from the front of the column ; but excretion.

Chap. VI. ACROPEKA, AND SOME ALLIED GENERA. 169

which bears the viscid cap is often left sticking within
the chamber, with the pollen-masses close outside.
Many flowers were thus treated, and three of them
produced fine capsules. Mr. Scott also succeeded in
fertilising two flowers in the same apparently unnatural
manner, as he likewise did on one occasion by placing
a pollen-mass, moistened with the viscid matter from a
distinct kind of Orchis, at the mouth of the stigmatic
chamber. These facts lead me to suspect that an
insect with the extremity of its abdomen produced
into a sharp point alights on the flower, and then turns
round to gnaw the distal portion of the labellum. In
doing so it removes the pollinium, the viscid cap of
which adheres to the extremity of its abdomen. The
insect then visits another flower, by which time the
movement of depression will have caused the pedicel
to lie flat on its back ; and from occupying the same
position as before, the insect will be apt to insert the
end of its abdomen into the stigmatic chamber, and
the viscid cap will then be scraped off by the ledge in
front, and the pollen-masses will be left close outside,
as in the above experiments. The whole operation
would probably be aided by the oscillatory movement
of the labellum whilst gnawed by an insect. This
whole view is very improbable, but it is the only one,
as far as I can see, which explains the fertilisation of
the flower.

The allied genera Gongora, Acineta, and Stanhopea
present nearly the same difficulty from the narrowness
of the entrance into the stigmatic chamber. Mr.
Scott tried repeatedly but in vain to force the pollen-
masses into the stigma of Gongora atro-purpurea and
truncata ; but he readily fertilised them by cutting off
the clinandrum and placing pollen-masses on the now
exposed stigma; as he likewise did in the case of

170 VANDE^. Chap. VL

Acropera. Dr. Criiger says* that Gongora maculata
"often bears fruit in Trinidad. It is visited, exclu-
sively during the day, as far as I can see, by a splendid
bee, probably a Euglossa, but with the tongue nearly
twice as long as the body. The tongue passes out
behind the abdomen, and is there curved upwards.
As these bees only come for biting and gnawing the
anterior side of the labellum, the protruding tongue
touches or approaches the gland (i. e., viscid disc) at
every retrograde movement of the insect. By this it
can hardly fail to be loaded sooner or later with the
pollen-masses, which are then easily inserted into the
stigmatic cleft. I have, however, not as yet observed
this fact." I am surprised that Dr. Criiger should
speak of the pollen-masses being easily inserted, and I
suppose that he must have experimented with dried
and shrunken ones. The doubled-up, immensely elon-
gated proboscis, projecting beyond the abdomen, would
answer as well as a pointed extremity to the abdomen,
which in the case of Acropera I imagine is the instru-
ment for removing the pollen-masses ; but I presume
that with Gongora it is not the viscid disc, but the
broad and free ends of the pollen-masses which are in-
serted into the stigmatic cavity. As in the case of
Acropera, I found it scarcely possible to insert the
pollen-masses of Gongora into the stigma; but some
which were removed from the anther and left exposed
to the sun for nearly five hours, became much shrunk
and formed thin sheets ; and these could be inserted
without much difficulty into the cleft-like entrance
of the stigma. The pollinia attached to an insect
flying about in the torrid zone would shrink after a
time; and the delay thus caused would ensure the

* ' Journ. Linn. Soc. Bot.' vol. viii. 18G4, p. 131.

Chap. VI. ACROPERA, AND SOME ALLIED GENERA. 171

flowers being fertilised with pollen from a distinct
plant.

With respect to Stanhopea, Dr. Criiger says* that
in the West Indies a bee (Euglossa) often visits the
flowers for the sake of gnawing the label lum, and he
caught one with a pollinium attached to its back ; but
he adds that he cannot understand how the pollen-
masses are inserted into the narrow mouth of the stigma.
With Stanhopea oculata I found that the pollinia could
almost always be attached to my naked or gloved
finger, by gently sliding it down the concave surface
of the arched column ; but this occurred only within a
short time after the expansion of the flowers, whilst
they are highly odoriferous. By again sliding my
finger down the column, the pollinia were almost
always rubbed off by the sharp edge of the stigmatic
chamber, and were left adhering close to its entrance.
Flowers thus treated occasionally, though rarely,
yielded capsules. The removal of the pollinia from
my finger seemed to depend on the existence of a
point projecting beyond the viscid disc, and which I
suspect is specially adapted for this purpose. If this
be so, the pollen-masses must emit their tubes without
being inserted into the stigmatic chamber. I may
add that the pollen-masses shrink very little by being
thoroughly dried, and could not in this state be easily
inserted.

The entrance into the stigma is in like manner,
as I hear from Fritz Miiller, f so much contracted in
Cirrhaea and Notylia, w7hich belong to another sub-
division of the Vandese, that the pollinia can be inserted

* 'Journ. Linn. Soc. Bot.' vol. translation of the first edition of

viii. 18G4, p. 130. Bronn has this work.

described the structure of Stan- f ' Bot. Zeitung,' 1868, p. 630.
hopea devoniensis, in his German

172 VANDEiE. Chap. VI.

into it only with extreme difficulty. In the case of
Cirrhaea, he found that this could be effected more
easily, after they had shrunk a little from being left
to dry for half an hour or an hour. He observed two
flowers with pollen-masses naturally inserted by some
means into their stigmas. On several occasions after
forcing the end of a pollen-mass into the mouth of the
stigma, he witnessed a most curious process of deglu-
tition. The extremity of the pollen-mass swells from
imbibing moisture, and as the chamber gradually
widens downwards, the swelling part is forced down-
wards ; so that the whole is at last drawn inwards and
disappears. In the case of Notylia, Fritz Muller ob-
served that the entrance into the stigma became a
little larger after the flower had remained expanded
for about a week. In whatever manner this latter
plant is fertilised, it is certain that it must be im-
pregnated with pollen from a distinct plant ; as it
offers one of those extraordinary cases in which its own
pollen acts like poison on the stigma.

In the last edition of this work it was shown that
the ovaria of mature flowers of Acropera do not con-
tain any ovules. But I erred greatly in the interpre-
tation of this fact, for 1 concluded that the sexes were
separate. I was however soon convinced of my error
by Mr. Scott, who succeeded in artificially fertilising
the flowers with their own pollen. A remarkable dis-
covery by Hildebrand, * namely, that in many Orchids
the ovules are not developed unless the stigma is
penetrated by the pollen-tubes, and that their develop-
ment occurs only after an interval of several weeks
or even months, explains the state of the ovarium
in Acropera, as observed by me. According also to

Bot. Zeitung,' 18G3, Oct. 30, et seq, and Aug. 4, 1865.

Chap VI. CORYANTHES. 173

Fritz Miiller, * the ovules of many endemic Epidendreae
and Vandea) in Brazil remain in a very imperfect state
of development for some months, and even in one case
for half a year, after the flowers had been fertilised.
He suggests that a plant which produces hundreds of
thousands of ovules, would waste much power if these
were formed and did not happen to be fertilised, and
we know that fertilisation is a doubtful and difficult
operation with many Orchids. It would therefore be
an advantage to such plants, if the ovules were not at
all developed until their fertilisation was assured by
the pollen- tubes having already penetrated the stigma.

Coryanthes. — I will conclude this chapter by giving
an account of the fertilisation of the flowers of Cory-
anthes, which is effected in a manner that might perhaps
have been inferred from their structure, but would have
appeared utterly incredible had it not been repeatedly
witnessed by a careful observer, namely, the late Dr.
Criiger, Director of the Botanical Gardens at Trinidad.
The flowers are very large and hang downwards. The
distal portion of the labellum (L) in the following wood-
cut, fig. 27, is converted into a large bucket (B). Two
appendages (H), arising from the narrowed base of the
labellum, stand directly over the bucket and secrete so
much fluid that drops may be seen falling into it.
This fluid is limpid and so slightly sweet that it does
not deserve to be called nectar, though evidently of the
same nature ; nor does it serve to attract insects. M.
Meniere estimates that the total quantity secreted by
a single flower is about an English ounce, f When
the bucket is full the fluid overflows by the spout (P).

* « Bot. Zeitung.' 1868, p. 164.

f 4 Bulletin de la Soo. Bot. dc France,' torn. ii. 1855, p. 351.

171

VrANDE.E.

Chap. VL

Fig. 27.

Coryanthes speciosa. (Copied from Lindley's ' Vegetable Kingdom.')

L. labellum.

B. bucket of the labellum.

H. fluid-secreting appendages.

P. spout of bucket, over-arched by
the end of the column, bearing
the anther and stigma.

Chap. VI. CORYANTHES. 175

This spout is closely over-arched by the end of the
column, which bears the stigma and pollen-masses in
such a position, that an insect forcing its way out of
the bucket through this passage would first brush with
its back against the stigma and afterwards against the
viscid discs of the pollinia, and thus remove them.
We are now prepared to hear what Dr. Criiger says
about the fertilisation of an allied species, the C.
macrantha, the labellum of which is provided with
crests.* I may premise that he sent me specimens of
the bees which he saw gnawing these crests, and they
belong, as I am informed by Mr. F. Smith, to the genus
Euglossa. Dr. Criiger states that these bees may be
" seen in great numbers disputing with each other for
a place on the edge of the hypochil (i. e. the basal part
of the labellum). Partly by this contest, partly perhaps
intoxicated by the matter they are indulging in, they
tumble down into the * bucket/ half-full of a fluid
secreted by organs situated at the base of the column.
They then crawl along in the water towards the
anterior side of the bucket, where there is a passage
for them between the opening of this and the column.
If one is early on the look-out, as these Hymenopterae
are early risers, one can see in every flower how
fecundation is performed. The humble-bee, in forcing
its way out of its involuntary bath, has to exert itself
considerably, as the mouth of the epichil (i. e. the
distal part of the labellum) and the face of the column
fit together exactly, and are very stiff and elastic. The
first bee, then, which is immersed will have the gland

* ' Journal of Linn. Soc. Bot.' drawing of C.feildingii in * Jour-

?ol. viii. 1864. p. 130. There is nal of Hort. Soc' vol. iii. p. 16.

a drawing of this species in Pax- I am indebted to Mr. Thiselton

ton's ' Mag. of Botany/ vol. v. p. Dyer for informing me of these

31, but it is too complicated to be figures,
reproduced. There is also a

176 VANDEJS. Chap. VI

of the pollen -mass glued to its back. The insect then
generally gets through the passage, and comes out
with this peculiar appendage, to return nearly imme-
diately to its feast, when it is generally precipitated a
second time into the bucket, passing out through the
same opening, and so inserting the pollen-masses into
the stigma while it forces its way out, and thereby im-
pregnating either the same or some other flower. I
have often seen this ; and sometimes there are so many
of these humble-bees assembled that there is a continual
procession of them through the passage specified."

There cannot be the least doubt that the fertilisation
of the flower absolutely depends on insects crawling
out through the passage formed by the extremity of
the labellum and the over-arching column. If the
large distal portion of the labellum or bucket had been
dry, the bees could easily have escaped by flying away.
Therefore we must believe that the fluid is secreted by
the appendages in such extraordinary quantity and is
collected in the bucket, not as a palatable attraction
for the bees, as these are known to gnaw the labellum,
but for the sake of wetting their wings, and thus
compelling them to crawl out through the passage.

I have now described, perhaps in too much detail,
a few of the many contrivances by which the Vandeae
are fertilised. The relative position and shape of the
parts — friction, viscidity, elastic and hygrometric move-
ments, all nicely related to one another — come into
play. But all these appliances are subordinate to the
aid of insects. Without their aid, not a plant belong-
ing to this tribe, in the species of the twenty-nine
genera examined by me, would set a seed. It is also
certain in a majority of the cases, that insects withdraw
the pollinia only when retreating from the flower, and

Chap. VI CORYANTHES. 177

by carrying them away, effect a union between two
flowers, generally on distinct plants. This can hardly
fail to occur in all the many cases in which the pollinia
slowly change their position, when removed from the
rostellum, in order to assume a proper direction for
striking the stigma ; for the insects during this in-
terval will have had time to fly from the flowers on
one plant which will serve as the male, to those
on another plant which will serve as the female.

9

178 VANDEJE. Chap. Vn.

CHAPTEE Til.

VANDE.E continued, — CATASETIDiE

Catasetidae, the most remarkable of all Orchids — The mechanism by
which the pollinia of Catasetum are ejected to a distance and are
transported by insects — Sensitiveness of the horns of the rostellura
— Extraordinary difference in the male, female, and hermaphrodite
forms of Catasetum trideutatum — Mormodes ignea, curious structure
of the flowers; ejection of the pollinia — Mormodes luxata — Cyc-
noches ventricosum, manner of fertilisation.

I have reserved for separate description one sub-family
of the Vandeae, namely, the Catasetidae, which must, I
think, be considered as the most remarkable of all
Orchids.

I will begin with Catasetum. A brief inspection of
the flower shows that here, as with most other Orchids,
some mechanical aid is requisite to remove the pollen-
masses from their cells, and to carry them to the
stigmatic surface. We shall, moreover, presently see
that Catasetum is exclusively a male form; so that
the pollen-masses must be transported to the female
plant, in order that seed should be produced. The
pollinium is furnished with a viscid disc of huge size ;
but this, instead of being placed in a position likely
to touch and adhere to an insect visiting the flower, is
turned inwards and lies close to the upper and back
surface of a chamber, which must be called the stig-
matic chamber, though functionless as a stigma. There
is nothing in this chamber to attract insects ; and even
if they did enter it, the viscid surface of the disc could
not possibly come into contact with them.

Chap. VII. CATASETUM. 179

How then does Nature act ? She has endowed these
plants with, what must be called for want of a better
term, sensitiveness, and with the remarkable power of
forcibly ejecting their pollinia even to a considerable
distance. Hence, when certain definite points of the
flower are touched by an insect, the pollinia are shot
forth like an arrow, not barbed however, but having
a blunt and excessively adhesive point. The insect,
disturbed by so sharp a blow, or after having eaten its
fill, flies sooner or later away to a female plant, and,
whilst standing in the same position as before, the
pollen-bearing end of the arrow is inserted into the
stigmatic cavity, and a mass of pollen is left on its
viscid surface. Thus, and thus alone, can the five
species of Catasetum which I have examined be
fertilised.

In many Orchideae, as in Listera, Spiranthes, and
Orchis, the surface of the rostellum is so far sensitive,
that, when touched or when exposed to the vapour of
chloroform, it ruptures in certain defined lines. So it
is in the tribe of the Catasetidse, but with this re-
markable difference, that in Catasetum the rostellum is
prolonged into two curved tapering horns, or, as I shall
call them, antennae, which stand over the labellum
where insects alight. If these are touched even very
lightly, they convey some stimulus to the membrane
which surrounds and connects the disc of the pol-
linium with the adjoining surface, causing it instantly
to rupture; and as soon as this happens the disc is
suddenly set free. We have also seen in several
Vandese that the pedicels of the pollinia are fastened
flat down in a state of tension, and are highly elastic,
so that, when freed, they immediately spring up, appa-
rently for the sake of detaching the pollen-masses from
the anther-cells. In the genus Catasetum, on the

180 VANDE.E. Chjlp. VII.

other hand, the pedicels are fastened down in a curved
position ; and when freed by the rupture of the attached
edges of the disc, they straighten themselves with such
force, that not only do they drag the balls of pollen
together with the anther-cells from their places of
attachment, but the whole pollinium is jerked forward,
over and beyond the tips of the so-called antennae, to
the distance sometimes of two or three feet. Thus,
as throughout nature, pre-existing structures and capa-
cities are utilised for new purposes.

Gataseturri saccatum* — I will first describe the male
forms, belonging to five species, which are included
under the generic name of Catasetum. The general
appearance of the present species is represented in the
following woodcut, fig. 28. A side view of the flower,
with all the petals and sepals excepting the labellum
cut off, is shown by B ; and A gives a front view of
the column. The upper sepal and two upper petals
surround and protect the column ; the two lower sepals
project out at right angles. The flower stands more
or less inclined to either side, but with the labellum
downwards, as represented in the drawing. The dull
coppery and orange-spotted tints, — the yawning cavity
in the great fringed labellum, — the one antenna
projecting with the other hanging down — give to
these flowers a strange, lurid, and almost reptilian
appearance.

In front of the column, in the middle, the deep
stigmatic chamber (fig. 28, A, s), may be seen ; but this
is best shown in the section (fig. 29, C, s), in which a]l

* I am much indebted to Mr. magnificent collection of Orchids,

James Veitch of Chelsta for the generously sent me two fine spikes,

first specimen which I saw of and has aided me in the kindest

this Orchid ; subsequently Mr. manner with other specimens.
S. Kucker, so well known for his

Chap. VII. CATASETUM SACCATUM. 181

the parts are a little separated from each other, in
order that the mechanism may be intelligible. In
the middle of the roof of the stigmatic chamber, far
back (d, in A, fig. 28), the upturned anterior edge of
the viscid disc can just be seen. The upper mem-
branous surface of the disc, before it is ruptured, is
continuous with the fringed bases of the two antenna)
between which it lies. The rostellum projects over
the disc and stigmatic chamber (see section C, fig. 29),
and is prolonged on each side so as to form the two
antennas ; the middle part is covered b}| the ribbon-
like pedicel (jped.) of the pollinium. The lower end of
the pedicel is attached to the disc, and the upper end
to the two pollen-masses (p) within the anther-cell.
The pedicel in its natural position is held much
bowed round the protuberant rostellum ; when freed
it forcibly straightens itself, and at the same time its
lateral edges curl inwards. At an early period of
growth, it is continuous with the rostellum, but sub-
sequently becomes separated from it by the solution
of a layer of cells.

The pollinium when set free and after it has
straightened itself, is represented at D, fig. 29. Its
under surface, which lies in contact with the rostellum,
is shown at E, with the lateral edges of the pedicel
now curled inwards. In this latter view, the clefts in
the under sides of the two pollen-masses are shown.
Within these clefts, near their bases, a layer of strong
extensible tissue is attached, forming the caudicles, by
which the pollen-masses are united to the pedicel.
The lower end of the pedicel is joined to the disc by a
flexible hinge, which occurs in no other genus, so that
the pedicel can play backwards and forwards, as far as
the upturned end (fig. D) of the disc permits. The
disc is large and thick ; it consists of a strong upper

182

VANDE.E.

Chap. VII.

Fte. 28.

Catasetum saocatum

Chap. VII. CATASETUM SACCATUM.

183

Fig. 29.

...-7>

CATASETUM SACCATUM.

a. anther.

em. antennae of the rostellum.

d. disc of pollinium.

/. filament of anther.

g. germen or ovarium.

/. labellum.

p. pollen-masses.

pd or ped. pedicel of pollinium.

s. stigmatic chamber.

A. Front view of column.

B. Side view of flower, with all the

sepals and petals removed ex-
cept the labellum.

C. Diagrammatic section through

the column, with all the parts
a little separated.

D. Pollinium, upper surface.

E. Pollinium, lower surface, which

before removal lies in close
contact with the rostellum.

184 VANDEJ5. Chap. VII.

membrane, to which the pedicel is united, with an
inferior cushion of great thickness, of pulpy, flocculent,
and viscid matter. The posterior margin is much the
most viscid part, and this necessarily first strikes any
object when the pollinium is ejected. The viscid
matter soon sets hard. The whole surface of the disc
is kept damp before ejection, by resting close against
the roof of the stigmatic chamber ; but in the section
(fig. C) it is represented, like the other parts, a little
separated from the roof.

The connective membrane of the anther (a in all the
figures) is produced into a spike, which adheres loosely
to the pointed end of the column ; this pointed end
(/, fig. C) is homologically the filament of the anther.

The anther has this peculiar shape apparently for
the sake of leverage, so that it may be easily torn off
by a pull at its lower end, when the pollinium is
jerked out by the elasticity of the pedicel.

The labellum stands at right angles to the column,
or hangs a little downwards ; its lateral and basal
lobes are turned under the middle portion, so that an
insect can stand only in front of the column. In the
middle of the labellum there is a deep cavity, bordered
by crests. This cavity does not secrete nectar, but its
walls are thick and fleshy, with a slightly sweet nutri-
tious taste ; and it will presently be shown that they
are gnawed by insects. The extremity of the left-
hand antenna stands immediately over the cavity, and
would infalliby be touched by an insect visiting this
part of the labellum for any purpose.

The antennae are the most singular organs of the
flower, and occur in no other genus. They form rigid,
curved horns, tapering to a point. They consist of a
narrow ribbon of membrane, with the edges curled in-
wards so as to touch; each horn therefore is tubular,

Chap. VII. CATASETUM SACCATUM. 185

with a slit down one side, like an adder's fang. They
are composed of numerous, much elongated, generally-
hexagonal cells, pointed at both ends ; and these cells
(like those in most of the other tissues of the flower)
have nuclei with nucleoli. The antennae are prolonga-
tions of the sides of the anterior face of the rostellnm.
As the viscid disc is continuous with a little fringe of
membrane on each side, and as this fringe is continuous
with the bases of the antennae, these latter organs are
put into direct connection with the disc. The pedicel
of the pollinium passes, as already stated, between the
bases of the two antennae. The antennae are not free
for their whole length; but their exterior edges are
firmly united to and blend for a considerable space
with the margins of the stigmatic chamber.

In all the flowers which I examined, taken from
three plants, the two antennae which are alike in
structure occupied the same relative position. The
extreme part of the left-hand antenna bends upwards
(see B, fig. 28, in which the position is shown plainer
than in A), and at the same time a little inwards, so
that its tip is medial and guards the entrance into
the cavity of the labellum. The right-hand antenna
hangs down, with its tip turned a little outwards ; and
as we shall immediately see, is almost paralysed, so as
to be functionless.

Now for the action of the parts. When the left-
hand antenna of this species (or either of the antennae
in three of the following species) is touched, the edges
of the upper membrane of the disc, which are con-
tinuously united with the surrounding surface, instantly
rupture, and the disc is set free. The highly elastic
pedicel then instantly flirts the heavy disc out of the
stigmatic chamber with such force, that the whole
pollinium is ejected, bringing away with it the two

186 VANDEJS. Chap. VII.

balls of pollen, and tearing the loosely attached spike-
like anther from the top of the column. The pollinium
is always ejected with its viscid disc foremost. I
imitated the action with a minute strip of whalebone,
slightly weighted at one end to represent the disc;
this was then bent half round a cylindrical object,
the upper end being at the same time gently held by
the smooth head of a pin, to represent the retarding
action of the anther, the lower end was then suddenly
set free, and the whalebone was pitched forward, like
the pollinium of the Catasetum, with the weighted
end foremost.

That the disc is first jerked out of the stigmatic
chamber, I ascertained by pressing the middle of the
pedicel ; and when I touched the antenna the disc
instantly sprung forth, but, owing to the pressure on
the pedicel, the pollinium was not dragged out of the
anther-cell. Besides the spring from the straighten-
ing of the pedicel, elasticity in a transverse direction
comes into play : if a quill be split lengthways, and
the half be forced longitudinally on a too thick pencil,
immediately the pressure is removed the quill jumps
off; and an analogous action takes place with the
pedicel of the pollinium, owing to the sudden inward
curling of its edges, when set free. These combined
forces suffice to eject the pollinium with considerable
force to the distance of two or three feet. Several
persons have told me that, when touching the flowers
of this genus in their hothouses, the pollinia have
struck their faces. I touched the antennae of C. cal-
losum whilst holding the flower at about a yard's
distance from a window, and the pollinium hit the
pane of glass, and stuck by its adhesive disc, to the
smooth vertical surface.

The following observations on the nature of the

Ouap. VII. CATASETUM. 187

excitement which causes the disc to separate from the
surrounding parts, include some made on the following
species. Several flowers were sent me by post and by
the railroad, and must have been much jarred, but
they had not exploded. I let two flowers fall from a
height of two or three inches on the table, but the
pollinia were not ejected. I cut off with a crash with
a pair of scissors the thick labellum and ovarium
close beneath the flower ; but this violence produced
no effect. Nor did deep pricks in various parts of the
column, even within the stigmatic chamber. A blow,
sufficiently hard to knock off the anther, causes the
ejection of the pollinium, as occurred to me once
by accident. Twice I pressed rather hard on the
pedicel, and consequently on the underlying ros-
tellum, without any effect. Whilst pressing on the
pedicel, I gently removed the anther, and then the
pollen-bearing end of the pollinium sprang up from
its elasticity, and this movement caused the disc to
separate. M. Meniere,* however, states that the
anther-case sometimes detaches itself, or can be gently
detached, without the disc separating ; and that then
the upper end of the pedicel, bearing the pollen-masses,
swings downwards in front of the stigmatic chamber.

After trials made on fifteen flowers of three species,
I find that no moderate degree of violence on any
part of the flower, except on the antennae, produces
any effect. But when the left-hand antenna of G.
saccatum, or either antenna of the three following
species, is touched, the pollinium is instantly ejected.
The extreme tip and the whole length of the antennae
are sensitive. In one specimen of C. triclentatum a
touch from a bristle sufficed ; in five specimens of

* 'Bull, de la Soc. Bot. de France," torn. i. 1854, p. 367.

188 VANDE.E. Chap. VIL

G. saccatum a gentle touch from a fine needle was
necessary ; but in four other specimens a slight blow
was requisite. In G tridentatum a stream of air and
of cold water from a small pipe did not suffice ; nor
in any case did a touch from a human hair ; so that
the antennae are less sensitive than the rostellum of
Listera. Such extreme sensitiveness would indeed
have been useless to the plant, for, as is now known,
the flowers are visited by powerful insects.

That the disc does not separate owing to the simple
mechanical movement of the antennas is certain; for
they adhere firmly for a considerable space to the
sides of the stigmatic chamber, and are thus im-
movably fixed near their bases. If a vibration is
conveyed along them, it must be of some special
nature, for ordinary jars of manifold greater strength
do not excite the act of rupture. The flowers in some
cases, when they first arrived, were not sensitive, but
after the cut-off spikes had stood for a day or two in
water they became sensitive. Whether this was owing
to fuller maturity or to the absorption of water, I know
not. Two flowers of G. caUosum, which were completely
torpid, were immersed in tepid water for an hour;
and then the antennae became highly sensitive ; this
indicates either that the cellular tissue of the antennae
must be turgid in order to receive and convey the
effects of a touch, or, as is more probable, heat in-
creases their sensitiveness. Two other flowers placed
in hot water, but not so hot as to scald my fingers,
spontaneously ejected their pollinia. A plant of G.
tridentatum had been kept for some days in a rather
cool house, and the antennae were consequently in a
torpid condition ; a flower was cut off and placed in
water at a temperature of 100° F. (37*7° C), and no
effect was immediately produced ; but when it was

Chap. VII. CATASETUM. 189

looked at after an interval of lh 30m the pollinium was
found ejected. Another flower was placed in water at
90° F. (32-2° C), and after 25m- the pollinium was found
ejected : two other flowers left for 20m- in water at
87° F. (30*5° C.) did not explode, though they were after-
wards proved to be sensitive to a slight touch. Lastly,
four flowers were placed in water at 83° F. (28*3° C.) ;
two of these did not eject their pollinia in 45m, and
were then found to be sensitive ; whereas the other two,
when looked at after lh 15™*, had spontaneously ejected
their pollinia. These cases show that immersion in
water raised to a temperature only a little higher than
that to which the plant had been exposed, causes the
membrane by which the discs are attached to rupture.
A thin stream of almost boiling water was allowed to
fall through a line pipe on the antennae of some flowers
on the above plant ; these were softened and killed
but the pollinia were not ejected. Nor did sulphuric
acid, dropped on the tips of the antennae, cause any
action ; though their upper parts which had not
been injured by the acid were afterwards found to be
sensitive to a touch. In these two latter cases, I
presume that the shock was so sudden and violent
that the tissue was instantly killed. Considering
the above several facts, we may infer that it must
be some molecular change which is conveyed along
the antennae, causing the membrane round the discs to
rupture. In G. tridentatum the antennae were one inch
and a tenth in length, and a gentle touch from a bristle
on the extreme tip was conveyed, as far as I could
perceive, instantaneously throughout this length. I
measured several cells in the tissue composing the
antennae of this species, and on a rough average it
appeared that the stimulus must travel through no less
than from seventy to eighty cells.

190 VANDE.E. Chap. VH.

We may, at least, safely conclude that the antennae,
which are characteristic of the genus Catasetum, are
specially adapted to receive and convey the effects of
a touch to the disc of the pollinium. This causes the
membrane to rupture, and the pollinium is then ejected
by the elasticity of its pedicel. If we required further
proof, nature affords it in the case of the so-called
genus Monachanthus, which, as we shall presently see,
is the female of Catasetum tridentatum, and it does not
possess pollinia which can be ejected, and the antennae
are here entirely absent.

I have stated that in C. saccatum the right-hand
antenna invariably hangs down, with the tip turned
slightly outwards, and that it is almost paralysed. I
ground my belief on five trials, in which I violently
hit, bent, and pricked this antenna, and this produced
no effect ; but when immediately afterwards the left-
hand antenna was touched with much less force, the
pollinium was shot forth. In a sixth case a forcible
blow on the right-hand antenna did cause the act of
ejection, so that it is not completely paralysed. As
this antenna does not guard the labellum, which in all
Orchids is the part attractive, that is to insects, its
sensitiveness would be useless.

From the large size of the flower, more especially
of the viscid disc, and from its wonderful power of
adhesion, I formerly inferred that the flowers were
visited by large insects, and this is now known to be
the case. The viscid matter sticks so firmly after it
has set hard, and the pedicel is so strong (though very
thin and only one-twentieth of an inch in breadth at
the hinge), that to my surprise a pollinium attached
to an object supported for a few seconds a weight of
1262 grains, or nearly three ounces ; and it supported
for a considerable time a slightly less weight. When

Chap. VII.

CATASETUM.

191

the pollinium is shot forth, the large spike-like anther
is generally carried with it. If the disc strikes a flat
surface like a table, the momentum from the weight
of the anther often carries the pollen-bearing end
beyond the disc, and the pollinium is thus affixed in
a wrono; direction for the fertilisation of another
flower, supposing it to have been attached to an
insect's body. The flight of the pollinium is often
rather crooked. * But it must not be forgotten that
under nature the ejection is caused by the antennae
being touched by a large insect standing on the la-
bellum, which will thus have its head and thorax
placed near to the anther. A rounded object thus
held is always accurately struck in the middle, and
when removed with the pollinium adhering to it, the
weight of the anther depresses the hinge of the pol-
linium ; and in this position the anther-case readily
drops off, leaving the balls of pollen free, in a proper
position for fertilising the female flower. The utility

* M. Baillon (' Bull, de la Soc.
Bot. de France,' torn. i. 1854, p.
285) states that Catasetum luridum
ejects its pollinia always in a
straight line, and in such a direc-
tion that it sticks fast to the
bottom of the concavity of the
labellum ; and he imagines that
in this position it fertilises the
flower in a manner not clearly
explained. In a subsequent paper
in the same volume (p. 307) M.
Meniere justly disputes M. Bail-
Ion's conclusion. He remarks
that the anther-case is easily de-
tached, and sometimes naturally
detaches itself ; the pollinia then
swing downwards by the elasticity
of the pedicel, the viscid disc still,
remaining attached to the roof
of the stigmatic chamber. M.
Meniere hints that, by the subse-

quent and progressive retraction
of the pedicel, the pollen -masses
might be carried into the st'gmatic
chamber. This is not possible in
the three species which I have
examined, and would be useless.
But M. Me'niere himself then goes
on to show how important insects
are for the fertilisation of Orchids ;
and apparently infers that their
agency comes into play with
Catasetum, and that this plant
does not fertilise itself. Both M.
Baillon and M. Me'niere correctly
describe the curved position in
which the elastic pedicel lies
before it is set free. Neither of
these botanists seems to be aware
that the species of Catasetum
(at least the five which I have
examined) are exclusively male
plants.

192 VANDEJE. Chap. VII.

of so forcible an ejection no doubt is to drive the soft
and viscid cushion of the disc against the hairy thorax
of the large hymenopterous insects which frequent the
flowers. When once attached to an insect, assuredly
no force which the insect could exert would remove
the disc and pedicel ; but the caudicles are ruptured
without much difficulty, and thus the balls of pollen
might readily be left on the adhesive stigma of the
female flower.

Catasetum callosum. — The flowers of this species * are
smaller than those of the last, but resemble them in
most respects. The edge of the labellum is covered
with papillae ; the cavity in the middle is small, and
behind it there is an elongated anvil-like projection,
— facts which I mention from the resemblance in some
of these points between the labellum of this species
and that of Myanthus barbatus, the hermaphrodite form
of Catasetum tride?itatum, presently to be described.
When either antenna is touched, the pollinium is
ejected with much force. The yellow-coloured pedicel
is much bowed, and is joined by a hinge to the ex-
tremely viscid disc. The two antennae stand sym-
metrically on each side of the anvil-like projection,
with their tips lying within the small cavity of the
labellum. The walls of this cavity have a pleasant
nutritious taste. The antennae are remarkable, from
their whole surface being roughened with papillae.
The plant is a male, and the female form is at present
unknown.

Catasetum tabulare. — This species belongs to the
same type as C. saccatum, but differs greatly from it in
appearance. The central portion of the labellum con-
sists of a narrow, elongated, table-like projection, of

* A fine sp'ke of flowers of this Mr. Rucker, and was named for
species was kindly sent me by me by Dr. Lindlt-y.

Chap. VII. CATASETUM TRIDENTATUM. 193

an almost white colour and formed of a thick mass
of succulent tissue, having a sweetish taste. Towards
the base of the labellum there is a large cavity, which
externally resembles the nectary of an ordinary flower,
but apparently never contains nectar. The pointed
extremity of the left-hand antenna lies within this
cavity, and would infallibly be touched by an insect
gnawing the bilobed and basal end of the medial pro-
jection of the labellum. The right-hand antenna is
turned inwards, with the extreme part bent at right
angles and pressed against the column; therefore I
do not doubt that it is paralysed as in C. saccatum ;
but the flowers examined by me had lost almost all
their sensitiveness.

Catasetum planicej)s (?). — This species does not differ
much from the following one, so I will describe it
briefly. The green and spotted labellum stands on
the upper side of the flower ; it is jar-shaped, with
a small orifice. The two elongated and roughened
antennae lie coiled up some little way apart and
parallel to one another, within the labellum. They
are both sensitive to a touch.

Catasetum tridentatum. — The general appearance
of this species, which is very different from that of
C. saccatum, callosum and tabular e, is represented in
fig. 30, with a sepal on each side cut off.

The flower stands with the labellum uppermost, that
is, in a reversed position compared with most Orchids.
The labellum is helmet-shaped, its distal portion being
reduced to three small points. It cannot hold nectar
from its position ; but the walls are thick, and have, as
in the other species, a pleasant nutritious taste. The
stigmatic chamber, though functionless as a stigma,
is of large size. The summit of the column, and the
spike-like anther, are not so much elongated as in

194

MONACHANTHUS VIRIDIS.

Chap. Vll.

C. saccatum. In other respects there is no important
difference. The antennae are of greater length ; their
tips for about one-twentieth of their length arc
roughened by cells produced into papilla?.

Fiff. 30.

Catasetum tridentatum.

a. anther.

pd. pedicel of pollinium.

an. antennae.

/. labellum.

A. Side view of flower in its natural

position, with two of the sepals
cut off.

B. Front view of column, in position
j reverse of fig. A.

The pedicel of the pollinium is articulated as before
by a hinge to the disc ; it can move freely only in one
direction owing to one end of the disc being upturned,
and this restricted power of movement apparently
comes into play when the pollinium is carried by an
insect to the female flower. The disc is, as in the other
species, of large size, and the end which when ejected
first strikes any object, is much more viscid than the
rest of the surface. This latter surface is drenched
with a milky fluid, which, when exposed to the air,
rapidly turns brown, and sets into a cheesy consistence.
The upper surface of the disc consists of strong mem-

Chap. VII. CATASETUM TKIDENTATUM. 195

brane formed of polygonal cells, resting on and adhering
to a thick cushion, formed of irregular rounded balls
of brown matter, separated from each other and em-
bedded in a transparent, structureless, highly elastic
substance. This cushion towards the posterior end of
the disc graduates into viscid matter, which when
consolidated is brown, translucent, and homogeneous.
Altogether the disc of Catasetum presents a much
more complex structure than in the other Vandeae.

I need not further describe the present species,
except as to the position of the antennae. They oc-
cupied exactly the same position in all the many
flowers which were examined. Both lie curled within
the helmet-like labellum ; the left-hand one stands
higher up, with its inwardly bowed extremity in the
middle ; the right-hand antenna lies lower down and
crosses the whole base of the labellum, with the tip
just projecting beyond the left margin of the base of
the column. Both are sensitive, but apparently the
one which is coiled within the middle of the labellum
is the more sensitive of the two. From the position
of the petals and sepals, an insect visiting the flower
would almost certainly alight on the crest of the la-
bellum; and it could hardly gnaw any part of the
great cavity without touching one of the two antennae,
for the left-hand one guards the upper part, and the
right-hand one the lower part. When either of these
is touched the pollinium is ejected and the disc will
strike the head or thorax of the insect.

The position of the antennae in this Catasetum may
be compared with that of a man with his left arm raised
and bent so that his hand stands in front of his chest,
and with his right arm crossing his body lower down
so that the fingers project just beyond his left side.
In Catasetum callosum both arms are held lower down

196 VANDE^E. Chap. VII.

and are extended symmetrically. In G. saccatum the
left arm is bowed and held in front, as in G. triden-
tatum, but rather lower down ; whilst the right arm
hangs downwards paralysed, with the hand turned a
little outwards. In every case notice will be given in
an admirable manner, when an insect visits the label-
lum, and the time has arrived for the ejection of the
pollinium, so that it may be transported to the female
plant.

Catasetum tridentatum is interesting under another
point of view. Botanists were astonished when Sir R.
Schomburgk* stated that he had seen three forms,
believed to constitute three distinct genera, namely,
Catasetum tridentatum, Monachanthus viridis, and
Myanthus barhatus, all growing on the same plant.
Lindley remarked f that "such cases shake to the
foundation all our ideas of the stability of genera and
species." Sir R. Schomburgk affirms that he has seen
hundreds of plants of G tridentatum in Essequibo with-
out ever finding one specimen with seeds ; J whereas

* 'Transactions of the Lirmt an Bristol. Lastly Dran Herbert

Soc' vol. xvii. p. 522. Another informed me many years ago that

account by Dr. Lindley appeared Catasetum luridum flowered and

in the 'Botanical Register,' fol. kept true for nine years in the

1951, of a distinct species of My- Botanic Garden at York ; it then

anthus and Monachanthus appear- threw up a scape of a Myanthus,

ing on the same scape : he alludes which as we shall prtsently tee is

also to other cases. Some of the an hermaphrodite, intermediate in

flowers in these cases were in an in- form between the male and fomale.

termediate condition, which is not M. Duchartro has given a full his-

surprising, t-eeing that in dioecious tori<al account of the appearance

plants we sometimes have a p trtial of these forms on the same plant,

resumption of the characters of in 'Bull, de la Soc. Bot. de

both sexes. Mr. R< dgers of River- France,' vol. ix. 1862, p. 113.

hill informs me that he imported t The 'Vegetable Kingdom/

from Demerara a Myanthus, and 1853, p. 178.

that when it flowered a second % Brongniart states (' Bull, de

time it was metamorphosed into la Soc. But. de France,' torn. ii.

a Catasetum. Dr. Carpenter 1855, p. 20) that M. Neumann, a

('Comparative Physiology,' 4th skilful fertiliser of Orchids, could

edit. p. 633) alludes to an ana- never succeed in fertilising Cata-

logous case which occurred at sutum.

Chap. VII. CATASETUM TRIDENTATUM. 197

he was surprised at the gigantic seed-vessels of the
Monachanthus ; and he correctly remarks that " here
we have traces of sexual difference in Orchideous
flowers." Dr. Criiger also informs me that in Trinidad
he never saw capsules naturally produced by the
flowers of this Catasetum ; * nor when they were fer-
tilised by him with their own pollen, as was done
repeatedly. On the other hand, when he fertilised
the flowers of the Monachanthus viridis with pollen
from the Catasetum, the operation never failed. The
Monachanthus also commonly produces fruit in a state
of nature.

From what I had myself observed, I was led to
examine carefully the female organs of G. tridentatum,
callosum, and saccatum. In no case was the stigmatic
surface viscid, as it is in all other Orchids (except as
we shall hereafter see in Cypripedium), and as is
indispensable for securing the pollen-masses by the
rupture of the caudicles. I carefully looked to this
point both in young and old flowers of C. tridentatum.
When the surface of the stigmatic chamber and of the
stigmatic canal of the above-named three species is
scraped off, after having been kept in spirits, it is found
to be composed of utriculi (including nuclei of the
proper shape), but not nearly so numerous as with
ordinary Orchids. The utriculi cohere more together

* Dr. Hance writes to me that often occurred. J. G. Beer says

he lias in bis collection a plant of (quoted by Irmisch, * Beitrage zu

Catasetum tridentatum from the Biologie der Orchideen,' 1853, p.

West Indies bearing a tine capsule; 22) that during three years he

but it does not appear to have tried in vain to fertilise Catasetum,

been ascertained that this par- but on one occasion, by placing

ticular flower was that of Cata- only the viscid disc of a pollinium

Bctum. and tbere is no great im- within the stigma, a ripe fruit

probability iu a single flower of was produced ; but it may be

Monachanthus being produced by asked, Did the seeds contain

a plant of Catasetum. as well as a embryos?
whole scape, which we know has

198 VANDEiE. Chap. VII.

and are more transparent ; T examined for comparison
those of many kinds of Orchids which had been kept
in spirits, and in all found them much less transparent.
In G. tridentatum, the ovarium is shorter, much less
deeply furrowed, narrower at the base, and internally
more solid than in Monachanthus. Again, in all
three species of Catasetum the ovule-bearing cords
are short ; and the ovules present a considerably dif-
ferent appearance, in being thinner, more transparent,
and less pulpy than in the numerous other Orchids
examined for the sake of comparison. Perhaps these
bodies hardly ought to be called ovules, although they
correspond closely in general appearance and position
with true ovules, for I was unable in any case to make
out the opening of the testa and the included nucleus ;
nor were the ovules ever inverted.

From these several facts, namely, — the shortness,
smoothness, and narrowness of the ovarium, the short-
ness of the ovule-bearing cords, the state of the ovules
themselves, the stigmatic surface not being viscid, the
transparent condition of the utriculi, — and from neither
Sir R. Schomburgk nor Dr. Cruger having ever seen
C. tridentatum producing seed in its native home,
or when artificially fertilised, we may confidently
look at this species, as well as the other species of
Catasetum, as male plants.

With respect to Monachanthus viridis, and Myanthus
barbatus, the President of the Linnean Society has
kindly permitted me to examine the spike bearing
these two so-called genera, preserved in spirits, which
was sent home by Sir K. Schomburgk. The flower of
the Monachanthus (A, fig. 31) resembles pretty closely
in external appearance that of Catasetum tridentatum
(fig. 30). The labellum, which holds the same relative
position to the other parts, is not nearly so deep,

Chap. VII.

CATASETUM TRIDENT ATUM.

199

especially on the sides, and its edge is crenated. The
other petals and sepals are all reflexed, and are not so
much spotted as in the Catasetum. The bract at the
base of the ovarium is much larger. The whole column,

Fag. 81.

B. Myanthus barbatus.

a. anther.

cm. antennae.

I. labellum.

p. pollen-mass, rudimentary.

s. stigmatic cleft.

sep. two lower sepals.

A. MONACHANTHUS VIRIDIS.

A. Side view of Monach<mthus mri-

dis in its natural position. (The
shading in both drawings has
been added from Mr. Reiss'
drawing in the ' Linnean Trans-
actions.')

B. Side view of Myanthus barbatus

in its natural position.

especially the filament and the spike-like anther, are
much shorter ; and the rostellum is much less protu-
berant. The antennae are entirely absent, and the
pollen-masses are rudimentary. These are interesting

200 - VANDE^. Chap. VII.

facts, from corroborating the view taken of the function
of the antennae ; for as there are no pollinia to eject,
an organ adapted to convey the stimulus from the
touch of an insect to the rostellum would be useless.
I could find no trace of a viscid disc or pedicel, and
no doubt they had been lost ; for Dr. Criiger says *
that " the anther of the female flower drops off imme-
diately after the opening of the same, i. e. before the
flower has reached perfection as regards colour, size,
and smell. The disc does not cohere, or very slightly,
to the pollen-masses, but drops off about the same
time, -with the anther ;" leaving behind them the rudi-
mentary pollen-masses.

Instead of a large stigmatic chamber, there is a
narrow transverse cleft close beneath the small anther.
I was able to insert one of the pollen-masses of the
male Catasetum into this cleft, which from having been
kept in spirits was lined with coagulated beads of
viscid matter, and with utriculi. The utriculi, differ-
ently from those in Catasetum, were charged (after
having been kept in spirits) with brown matter. The
ovarium is longer, thicker near the base, and more
plainly furrowed than in Catasetum ; the ovule-bearing
cords are also much longer, and the ovules more opaque
and pulpy, as in all common Orchids. I believe that
I saw the opening at the partially inverted end of the
testa, with a large projecting nucleus ; but as the speci-
mens had been kept many years in spirits and were
somewhat altered, I dare not speak positively. From
these facts alone it is almost certain that Monachanthus
is a female plant; and as already stated, Sir R.
Schomburgk and Dr. Criiger have both seen it seeding
abundantly. Altogether the flower differs in a most

* ' Journ. Linn. Soc. Bot' vol. viii. 1864, p. 127.

Chap. VII. MONACHAKTHUS VIRIDIS. 201

remarkable manner from that of the male Catasetum
tridentatum, and it is no wonder that the two plants
were formerly ranked as distinct genera.

The pollen-masses offer so curious and good an illus-
tration of a structure in a rudimentary condition, that
they are worth description ; but I must first recur to
the perfect pollen-masses of the male Catasetum.
These may be seen at D and E, fig. 29, attached to
the pedicel : they consist of a large sheet of cemented
or waxy pollen-grains, folded over so as to form a
sack, with an open slit along the lower surface, within
which at the lower and produced end, a layer of highly
elastic tissue, forming the caudicle, is attached; the
other end being attached to the pedicel of the rostellum.
The exterior grains of pollen are more angular, have
thicker walls, and are yellower than the interior grains.
In the early bud the two pollen-masses are enveloped
in two conjoined membranous sacks, which are soon
penetrated by the two produced ends of the pollen-
masses and by their caudicles ; and afterwards the
extremities of the caudicles adhere to the pedicel.
Before the flower expands the membranous sacks in-
cluding the two pollen-masses open ; and the pollen-
masses are left resting naked on the back of the
rostellum.

In Monachanthus, on the other hand, the two mem-
branous sacks containing the rudimentary pollen-
masses never open ; but they easily separate from each
other and from the anther. The tissue of which they
are formed is thick and pulpy. Like most rudi-
mentary parts, the pollen-masses vary much in size
and form ; they are only about one-tenth of the bulk
of those of the male ; they are flask-shaped (p, fig. 31),
with the lower end greatly produced so as almost to
penetrate the exterior or membranous sack. There is
10

202 VANDEJE. Chap. VII.

no fissure along their lower surfaces for the protrusion
of the caudicles. The exterior pollen-grains are square
and have thicker walls than the interior grains, just as
in the proper male pollen ; and, what is very curious,
each cell has its nucleus. Now, K. Brown states * that
in the early stages of the formation of the pol] en-grains
of ordinary Orchids (as with other plants) a minute
nucleus is often visible ; so that the rudimentary pollen-
grains of Monachanthus apparently have retained — as
is so general with rudiments in the animal kingdom —
an embryonic character. Lastly, at the base, within
each flask-shaped pollen-mass, there is a little mass of
brown elastic tissue, — that is, a vestige of a caudicle, —
which runs far up the pointed end of the flask, but
does not (at least in some of the specimens) come to
the surface, and could never be attached to any part of
the pedicel. These rudimentary and enclosed caudicles
are, therefore, utterly useless. Notwithstanding the
small size and almost aborted condition of the female
pollen-masses, when they were placed by Dr. Criiger
within the stigma of a female plant they emitted " here
and there a rudimentary tube." The petals then faded
and the ovarium enlarged, but after a week it turned
yellow and finally dropped off without bringing any
seeds to perfection. This appears to me a very curious
instance of the slow and gradual manner in which
structures are modified ; for the female pollen-masses,
which can never be naturally removed or applied to
the stigma, still partially retain their former powers
and function.

Thus every detail of structure which characterises
the male pollen-masses is represented in the female
plant in a useless condition. Such cases are familiar to

Transactions of the Linnean Soc' vol. xvi. p. 711.

Chap. VII. JVIYANTHUS BARBATUS. 203

every naturalist, but can never be observed without
renewed interest. At a period not far distant, natura-
lists will hear with surprise, perhaps with derision, that
grave and learned men formerly maintained that such
useless organs were not remnants retained by inherit-
ance, but were specially created and arranged in their
proper places like dishes on a table (this is the simile
of a distinguished botanist) by an Omnipotent hand
* to complete the scheme of nature."

The third form, Myanthus harbatus (fig. 31, B), is
sometimes borne on the same plant together with the
two preceding forms. The flowers differ greatly in
external appearance, but not in essential structure,
from those of both the other forms. They generally
stand in a reversed position, compared with those of
Gatasetum tridentatum and of Monachanthus viridis,
that is, with the labellum downwards. The labellum
is fringed in an extraordinary manner with long
papillae ; it has a quite insignificant medial cavity,
at the hinder margin of which a curious curved and
flattened horn projects, which represents the anvil-like
projection on the labellum of the male G. callosum.
The other petals and sepals are spotted and elongated,
with the two lower sepals alone reflexed. The antennas
are not so long as in the male G. tridentatum; they
project symmetrically on each side of the horn-like
process at the base of the labellum, with their tips,
which are not roughened with papillae, almost entering
the medial cavity. The stigmatic chamber is of nearly
intermediate size between that of the male and female
forms; it is lined with utriculi charged with brown
matter. The straight and well-furrowed ovarium is
nearly twice as long as that of the female Monachan-
thus, but not so thick where it joins the flower ; the
ovules are opaque and pulpy after having been kept

204 VANDE^E. Chap. VII.

in spirits, and resemble those of the female in all
respects, but are not so numerous. I believe that I
saw the nucleus projecting from the testa, but dare
not, as in the case of the Monachanthus, speak posi-
tively. The pollinia are about a quarter of the size
of those of the male Catasetum, but have a perfectly
well developed disc and pedicel. The pollen-masses
were lost in the specimens examined by me ; but
Mr. Reiss has given, in the Linnean Transactions, a
drawing of them, showing that they are of due pro-
portional size and have the proper folded or cleft
structure, within which the caudicles are attached.
Thus as both the male and female organs are in
appearance perfect, Myanthus barbatus may be con-
sidered as an hermaphrodite form of the same species,
of which the Catasetum is the male and Monachan-
thus the female. Nevertheless, the intermediate forms,
which are common in Trinidad, and which resemWe
more or less closely the above described Myanthus,
have never been seen by Dr. Cruger to produce seed-
capsules.

It is a highly remarkable fact, that this sterile
hermaphrodite form resembles in its whole appearance
and structure the males of two other species, namely,
G. saceatum and more especially G. callosum, much
more closely than it does either the male or female
form of the same species. As all orchids, with the
exception of a few in the present small sub-family, as
well as all the members of several allied groups of
plants, are hermaphrodites, there can be no doubt
that the common progenitor of the Orchideae was
an hermaphrodite. We may therefore attribute the
hermaphrodite condition and the general appearance
of Myanthus to reversion to a former state; and if
so, the ancestors of all the species of Catasetum must

Chap. VII. CATASETUM TKIDENTATUM. 205

have resembled the males of G. saccatum and callosum,
for as we have just seen, it is to these two plants that
Myanthus presents so many striking resemblances.*

Lastly I may be permitted to add that Dr. Cruger,
after having carefully observed these three forms in
Trinidad, fully admits the truth of my conclusion that
Catasetum tridentatum is the male and Monachanthm
viridis the female of the same species. He further
confirms my prediction that insects are attracted to
the flowers for the sake of gnawing the labellum, and
that they carry the pollen-masses from the male to the
female plant. He says "the male flower emits a
peculiar smell about twenty-four hours after opening,
and the antennae assume their greatest irritability at
the same time. A large humble-bee, noisy and quarrel-
some, is now attracted to the flowers by the smell,
and a great number of them may be seen every morning
for a few hours disputing with each other for a place in
the interior of the labellum, for the purpose of gnawing
off the cellular tissue on the side opposite to the column,
so that they turn their backs to the latter. As soon as
they touch the upper antenna of the male flower, the
pollen-mass, with its disc and gland, is fixed on their
back, and they are often seen flying about with this
peculiar-looking ornament on them. I have never
seen it attached except to the very middle of the

* The male of the Indian ante- to reversion to a former sfate of

lope (A.bezoartica) after castration the sptcies; for we have good

produces horns of a widely dif- reason to believe that any cause

ferent shape from those of the which disturbs the constitution

perfect male; and larger and leads to reversion. Myanthus,

thicker than those occasionally though having the organs of both

produced by the female. We see sexes apparently perfect, is sterde;

something of the same kind in the it has therefore had its sexual

horns of the common ox. I have constitution disturbed, and this

remnrked in my ' Descent of Man ' seems to have caused it to revert

(2nd edit. p. 506), that such in character to a former state.
cases may probably be attributed

206 VANDE.E. Chap. VII.

thorax. When the bee walks about, the pollen-mass
lies flat on the back and wings ; but when the insect
enters a female flower, always with the labellum turned
upwards, the pollinium, which is hinged to the gland
by elastic tissue, falls back by its own weight and rests
on the anterior face of the column. When the insect
returns backwards from the flower, the pollinia are
caught by the upper margin of the stigmatic cavity,
which projects a little beyond the face of the column ;
and if the gland be then detached from the back of
the insect, or the tissues which connect the pollinia
with the caudicle, or this with the gland, break, fecun-
dation takes place." Dr. Criiger sent me specimens
of the humble-bees which he caught gnawing the
labellum, and these consist of Euglossa nov. spec, ca-
jennensis and piliventris.

Catasetum mentosum and a Monachanthus, according
to Fritz Muller,* grow in the same district of South
Brazil ; and he easily succeeded in fertilising the
latter with pollen from the former. The pollen-masses
could be inserted only partially into the narrow
stigmatic cleft ; but when this was done, a process of
deglutition, as described under Cirrhsea, commenced
and was slowly completed. On the other hand, Fritz
Muller entirely failed in his attempts to fertilise the
flowers of this Catasetum with its own pollen or with
that from another plant. The pollinia of the female
Monachanthus are very small ; the pollen-grains are
variable both in size and shape ; the anther never
opens, and the pollen-masses are not attached to
the caudicle. Nevertheless, when these rudimentary
pollen-masses, which can never naturally be removed
from their cells, were placed on the slightly viscid

* ■ Bot. Zcitung/ 1868, p. 630.

Chap. VII. CATASETUM. 207

stigma of the male Catasetum, they emitted their
tubes.

The genus Catasetum is interesting to an unusual
degree in several respects. The separation of the
sexes is unknown amongst other Orchids, except per-
haps in the allied genus Cycnoches. In Catasetum
we have three sexual forms, generally borne on sepa-
rate plants, but sometimes mingled together on the
same plant; and these three forms are wonderfully
different from one another, much more different than,
for instance, a peacock is from a peahen. But the
appearance of these three forms now ceases to be an
anomaly, and can no longer be viewed as an unparal-
leled instance of variability.

This genus is still more interesting in its manner of
fertilisation. We see a flower patiently waiting with
its antennae stretched forth in a well-adapted position,
ready to give notice whenever an insect puts its head
into the cavity of the labellum. The female Mona-
chanthus, not having true pollinia to eject, is destitute
of antennae. In the male and hermaphrodite forms,
namely Catasetum tridentatum and Myanthus barbatus,
the pollinia lie doubled up, like a spring, ready to be
instantly shot forth when the antennae are touched.
The disc end is always projected foremost, and is coated
with viscid matter which quickly sets hard and affixes
the hinged pedicel firmly to the insect's body. The
insect flies from flower to flower, till at last it visits a
female plant : it then inserts one of the pollen-masses
into the stigmatic cavity. As soon as the insect flies
away the elastic caudicle, made weak enough to yield
to the viscidity of the stigmatic surface, breaks, and
leaves behind a pollen-mass ; then the pollen-tubes
slowly protrude, penetrate the stigmatic canal, and the
act of fertilisation is completed. Who would have

208 VANDE^. Chap. VII.

been bold enough to have surmised that the propaga-
tion of a species depended on so complex, so apparently
artificial, and yet so admirable an arrangement ?

I have examined three other genera placed by
Lindley in the small sub-family of Catasetidoe, namely,
Mormodes, Cycnoches and Cyrtopodium. The latter
plant was purchased by me under this name, and bore
a flower-stem about four feet in height with yellowish
bracts spotted with red ; but the flowers presented
none of the remarkable peculiarities of the three other
genera, with the exception that the anther was hinged
to a point projecting from the summit of the column,
as in Catasetum.

Mormodes ignea. — To show how diffi cult it sometimes
is to understand the manner in which an Orchid is
fertilised, I may mention that I carefully examined
twelve flowers,* trying various experiments and re-
cording the results, before I could at all make out the
meaning and action of the several parts. It was plain
that the pollinia were ejected, as in Catasetum, but
how each part of the flower played its proper part I
could not even conjecture. I had given up the case
as hopeless, until summing up my observations, the
explanation presently to be given, and subsequently
proved by repeated experiments to be correct, suddenly
occurred to me.

The flower presents an extraordinary appearance,
and its mechanism is even more curious than its ap-
pearance (fig. 32). The base of the column is bent
backwards, at right angles to the ovarium or footstalk,

* I must expre-s my cordial two fine spikes, bearing an abun-

thanks to Mr. Rucker, of West dance of flowers, and for having

Hill, Wandsworth, for having lent allowed mo to keep the plant for

me a plant of this Mormodes with a considerable time.

Chap. VII.

MORMODES IGNEA.

209

and then resumes an upright position to near its
summit, where it is again bent. It is, also, twisted in
a unique manner, so that its front surface, including

Fig. 32.

MORMODES IGNEA.

Lateral view of flower, with the tipper sepal and the near upper petal

cut off.

N.B. The labellum in the drawing is a little lifted up, to show the de-
pression on its under surface, which ought to be pressed close down
on the bent summit of the column.

a. anther.

pd. pedicel of pollinium.

s. stigma.

/. labellum.
I. s. lateral sepal.

the anther, rostellum, and the upper part of the stigma
faces one side of the flower ; this being either to the

210 VANDEJE. Chap. VII.

right or left, according to the position of the flower
on the spike. The twisted stigmatic surface extends
down to the base of the column and is hollowed out
into a deep cavity at its upper end. The large viscid
disc of the pollinium is lodged in this cavity close be-
neath the rostellum ; and the rostellum is seen in the
drawing (pd.) covered by the bowed pedicel.

The anther-case (a in the figure) is elongated and
triangular, closely resembling that of Catasetum ; but
it does not extend up to the apex of the column. The
apex consists of a thin flattened filament, which from
the analogy of Catasetum I suppose to be the produced
filament of the stamen ; but it may be a prolongation
of some other element of the column. In the bud-
state it is straight, but before the flower expands, it
becomes much bent by the pressure of the labellum.
A group of spiral vessels runs up the column as far as
the summit of the anther-case ; they are then reflexed
and run some way down the anther-case. The point
of reflexion forms a short thin hinge by which the top
of the anther-case is articulated to the column beneath
its bent summit. The hinge, although smaller than a
pin's head in size, is of paramount importance ; for it
is sensitive and conveys the stimulus from a touch to
the disc of the pollinium, causing it to separate from
its place of attachment. The hinge also serves to
guide the pollinium during its ejection. As it has
to convey the necessary stimulus to the disc, one may
suspect that a portion of the rostellum, which lies in
close contact with the filament of the anther, runs up
to this point ; but I could not here detect any differ-
ence in structure on comparing these parts with those
of Catasetum. The cellular tissue round the hinge
is gorged with fluid, and a large drop exudes when
the anther is torn from the column during the ejection

Chap. VII. MORMODES IGNEA. 211

of the pollinium. This gorged condition may perhaps
facilitate the rupture of the hinge.

The pollinium does not differ much from that of
Catasetum (see fig. 29, D, p. 183); and it lies in like
manner curved round the rostellum, which is less protu-
berant than in that genus. The upper and broad end of
the pedicel, however, extends beneath the pollen-masses
within the anther ; and these are attached by rather
weak caudicles to a medial crest on its upper surface.

The viscid surface of the large disc lies in contact
with the roof of the stigmatic cavity, so that it cannot
be touched by an insect visiting the flower. The
anterior end of the disc is furnished with a small de-
pendent curtain (dimly shown in fig. 32) ; and this,
before the act of ejection, is continuously joined on
each side to the upper margins of the stigmatic cavity.
The pedicel is united to the posterior end of the disc ;
but when the disc is freed, the lowermost part of the
pedicel becomes doubly bent, so that it then appears
as if attached by a hinge to the centre of the disc.

The labellum is a highly remarkable structure : it
is narrowed at its base into a nearly cylindrical foot-
stalk, and its sides are so much reflexed as almost to
meet at the back, forming a folded crest on the sum-
mit of the flower. After rising up perpendicularly
it arches over the apex of the column, against which it
is firmly pressed down. The labellum at this point is
hollowed out (even in the bud) into a slight cavity,
which receives the bent summit of the column. This
slight depression manifestly represents the large cavity,
with thick fleshy walls, which insects gnaw, on the
anterior surface of the labellum in the several species
of Catasetum. Here by a singular change of function,
the cavity serves to keep the labellum in its proper
position on the summit of the column, but is, perhaps,

212 VANDEiE. Chap. VII

likewise attractive to insects. In the drawing (fig. 32)
the labellum has been forcibly raised a little up, so as
to show the depression and the bent filament. In its
natural position it may almost be compared to a huge
cocked-hat, supported by a footstalk and placed on the
head of the column.

The twisting of the column, which I have seen in
no other Orchid, causes all the important organs of
fructification in the flowers on the left side of the
spike to face to the left, and in all those on the right
side to face to the right. So that two flowers taken
from opposite sides of the same spike and held in
the same relative position are seen to be twisted in
opposite directions. One single flower, which was
crowded by the others, was barely twisted, so that its
column faced the labellum. The labellum is also
slightly twisted : for instance, in the flower figured,
which faced to the left, the midrib of the labellum was
first twisted to the right-hand, and then to the left, but
in a less degree, and being bent over it pressed on the
posterior surface of the crooked summit of the column.
The twisting of all the parts of the flower commences
in the bud.

The position thus acquired by the several organs is
of the highest importance; for if the column and
labellum had not been twisted laterally, the pollinia,
when shot forth, would have struck the overarching
labellum and have then rebounded, as actually oc-
curred with the single abnormal flower having a nearly
straight column. If the organs had not been twisted
in opposite directions on the opposite sides of the same
crowded spike, so as always to face to the outside, there
would not have been a clear space for the ejection of
the pollinia and their adhesion to insects.

When the flower is mature the three sepals hang

Chap. Vn. MORMODES IGNEA. 213

down, but the two upper petals remain nearly upright.
The bases of the sepals, and especially of the two
upper petals, are thick and swollen and have a
yellowish tint ; when quite mature, they are so gorged
with fluid, that, if punctured by a fine glass tube, the
fluid rises by capillary attraction to some height in it.
These swollen bases, as well as the footstalk of the
labellum, have a decidedly sweet and pleasant taste ;
and I can hardly doubt that they are attractive to
insects, for no free nectar is secreted.

I will now endeavour to show how all the parts of
the flower are co-ordinated and act together. The
pedicel of the pollinium is bowed round the rostellum,
as in Catasetum; in this latter genus, when freed,
it merely straightens itself with force, in Mormodes
something more takes place. If the reader will look
forward to fig. 34 (p. 223), he will see a section of the
flower-bud of the allied genus of Cycnoches, which
differs only in the shape of the anther and in the viscid
disc having a much deeper dependent curtain. Now
let him suppose the pedicel of the pollinium to be so
elastic that, when freed, it not only straightens itself,
but suddenly bends back on itself with a reversed
curvature, so as to form an irregular hoop. The
curved surface which was before in contact with
the protuberant rostellum now forms the outside
of the hoop. The exterior surface of the curtain,
which depends beneath the disc, is not viscid; and
it now lies on the anther-case, with the viscid surface
of the disc on the outside. This is exactly what takes
place with Mormodes. But the pollinium assumes
with such force its reversed curvature (aided, appa-
rently, by a transverse curling outwards of the margins
of the pedicel), that it not only forms itself into a
hoop, but suddenly springs away from the protuberant

214 VANDE.E. Chap. VII.

face of the rostellum. As the two pollen-masses
adhere, at first, rather firmly to the anther-case, the
latter is torn off by the rebound ; and as the thin
hinge at the summit of the anther-case does not yield
so easily as the basal margin, the pollinium together
with the anther-case is instantly swung upwards like a
pendulum. But in the course of the upward swing
the hinge yields, and the whole body is projected
perpendicularly up in the air, an inch or two above and
close in front of the terminal part of the labellum. If
no object is in the way, as the pollinium falls down,
it generally alights and sticks, though not firmly, on
the folded crest of the labellum, directly over the
column. I witnessed repeatedly all that has been
here described.

The curtain of the disc, which, after the pollinium
has formed itself into a hoop, lies on the anther-case,
is of considerable service in preventing the viscid edge
of the disc from adhering to the anther, and thus
permanently retaining the pollinium in the form of a
hoop. This would have been fatal, as we shall pre-
sently see, to a subsequent movement of the pollinium
which is necessary for the fertilisation of the flower.
In some of my experiments, when the free action
of the parts was checked, this did occur, and the
pollinium, together with the anther-case, remained
permanently glued together in the shape of an ir-
regular hoop.

I have already stated that the minute hinge by
which the anther-case is articulated to the column, a
little way beneath its bent filamentary apex, is sen-
sitive to a touch. I tried four times and found
that I could touch with some force any other part ;
but when I gently touched this point with the finest
needle, instantly the membrane which unites the disc

Chap. VII. MORMODES IGNEA. 215

to the edges of the stigmatic cavity where it is lodged,
ruptured, and the pollinium was shot upwards and fell
on the crest of the labellum as just described.

Now let us suppose an insect to alight on the
folded crest of the labellum, and no other convenient
landing-place is afforded, and then to lean over the
front of the column so as to gnaw or suck the bases of
the petals swollen with sweet fluid. The weight and
movements of the insect would disturb the labellum
and the bent underlying summit of the column ; and
the latter, pressing on the hinge in the angle, would
cause the ejection of the pollinium, which would in-
fallibly strike the head of the insect and adhere to
it. I tried by placing my gloved finger on the summit
of the labellum, with the tip just projecting beyond
its margin, and then gently moving my finger it was
really beautiful to see how instantly the pollinium
was projected upwards, and how accurately the viscid
surface of the disc struck my finger and firmly
adhered to it. Nevertheless, I doubt whether the
weight and movements of an insect would suffice to
thus act indirectly on the sensitive point ; but look
at the drawing and see how probable it is that an
insect leaning over would place its front legs over the
edge of the labellum on the summit of the anther-
case, and thus touch the sensitive point. The pol-
linium would then be ejected, and the viscid disc
would certainly strike and adhere to the insect's head.

Before proceeding, it may be worth while to mention
some of the early trials which I made. I pricked,
deeply the column in different parts, including the
stigma, and cut off the petals, and even the labellum,
without causing the ejection of the pollinium; this,
however, once happened when I cut rather roughly
through the thick footstalk of the labellum, the fila-

216 VANDE^. Chap. VII.

mentary summit of the column no doubt having been
thus disturbed. When I gently prised up the anther-
case at its base or on one side, the pollinium was
ejected, but then the sensitive hinge would necessarily
have been bent. When the flower has long remained
expanded and is nearly ready for spontaneous ejection,
a slight jar on any part of the flower causes the
action. Pressure on the thin pedicel of the pollinium,
and therefore on the underlying protuberant rostellum,
is followed by the ejection of the pollen-masses ; but
this is not surprising, as the stimulus from a touch
on the sensitive hinge has to be conveyed through
this part of the rostellum to the disc. In Catasetum
slight pressure on this point does not cause the act
of ejection ; but in this genus the protuberant part of
the rostellum does not lie in the course along which
the stimulus has to be conveyed from the antennae
to the disc. A drop of chloroform, of spirits of wine, or
of boiling water placed on this part of the rostellum
produced no effect ; nor, to my surprise, did exposure
of the whole flower to vapour of chloroform.

Seeing that this part of the rostellum was sensitive
to pressure, and that the flower was widely open on
one side, and being pre-occupied with the case of Cata-
setum, I at first felt convinced that insects entered the
lower part of the flower and touched the rostellum.
Accordingly I pressed the rostellum with variously-
shaped objects, but the viscid disc never once adhered
in a proper manner to the object. If I used a thick
needle, the pollinium, when ejected, formed a hoop
round it with the viscid surface outside ; if I used a
broad flat object, the pollinium struggled against it
and sometimes coiled itself up spirally, but the disc
either did not adhere at all, or very imperfectly. At
the close of the twelfth trial I was in despair. The

Chap. VII. MOKMODES IGNEA. 217

strange position of the labellum, perched on the summit
of the column, ought to have shown me that here was
the place for experiment. I ought to have rejected
the notion that the labellum was thus placed for no
good purpose. This plain guide was overlooked, and
for a long time I completely failed to understand the
structure of the flower.

We have seen that when the pollinium is ejected
and swings upwards, it adheres by the viscid surface
of the disc to any object projecting beyond the edge
of the labellum directly over the column. When thus
attached, it forms an irregular hoop, with the torn-off
anther-case still covering the pollen-masses which are
close to the disc, but protected from adhering to it
by the dependent curtain. Whilst in this position
the projecting and bowed part of the pedicel would
effectually prevent the pollen-masses from being placed
on the stigma, even supposing the anther-case to have
fallen off. Now let us suppose the pollinium to be
attached to an insect's head, and observe what takes
place. The pedicel, when first separated from the ros-
tellum, is damp; as it dries, it slowly straightens
itself, and when perfectly straight the anther-case
readily drops off. The pollen-masses are now naked,
and they are attached to the end of the pedicel by
easily ruptured caudicles, at the right distance and in
a proper position for their insertion into the adhesive
stigma, as soon as the insect visits another flower.
Thus every detail of structure is now perfectly adapted
for the act of fertilisation.

When the anther-case drops off, it has performed its
triple function ; namely, its hinge as an organ of sense,
its weak attachment to the column as a guide causing
the pollinium at first to swing perpendicularly upwards,
and its lower margin, together with the curtain of the

218 VANDE.E. Chap. YII

disc, as a protection to the pollen-masses from being
permanently glued to the viscid disc.

From observations made on fifteen flowers, it was
ascertained that the straightening of the pedicel does
not occur until from twelve to fifteen minutes have
elapsed. The first movement causing the act of ejec-
tion is due to elasticity, and the second slow movement
to the drying of the outer and convex surface ; but
this latter movement differs from that observed in the
pollinia of so many Yandeae and Ophrese, for, when
the pollinium of this Mormodes was placed in water,
it did not recover the hoop-like form which it had at
first acquired by elasticity.

The flowers are hermaphrodites. The pollinia are
perfectly developed. The elongated stigmatic surface
is extremely viscid and abounds with innumerable
utriculi, the contents of which shrink and become
coagulated after immersion for less than an hour in
spirits of wine. When placed in spirits for a day, the
utriculi were so acted on that they disappeared, and this
I have not noticed in any other Orchid. The ovules,
after exposure to spirits for a day or two, presented
the usual semi-opaque, pulpy appearance common to
all hermaphrodite and female Orchids. From the
unusual length of the stigmatic surface I expected
that, if the pollinia were not ejected from the excite-
ment of a touch, the anther-case would have detached
itself, and the pollen-masses would have swung down-
wards and fertilised the stigma of the same flower.
Accordingly, I left four flowers untouched ; after they
had remained expanded from eight to ten days, the
elasticity of the pedicel conquered the force of attach-
ment and the pollinia were spontaneously ejected, but
they did not fall on the stigma and were consequently
wasted.

Chap. VII. MORMODES LUXATA. 219

Although Mormodes ignea is an hermaphrodite, yet
it must be as truly dioecious in function as Catasetum ;
for as it takes from twelve to fifteen minutes before
the pedicel of an ejected pollinium straightens itself
and the anther-case drops off, it is almost certain that
within this time an insect with a pollinium attached
to its head would have left one plant and flown to
another.

Mormodes luxata. — This rare and fine species is ferti-
lised in the same manner as Mormodes ignea, but differs
in several important points of structure. The right
and left sides of the same flower differ from one another
even in a greater degree than in the last species. One
of the petals and one of the sepals project at right
angles to the column, while the corresponding ones
stand upright and surround it. The upturned and
twisted labellum is furnished with two large lateral
lobes : of these one embraces the column, while the
other stands partly open on the side where the one
petal and sepal lie flat. Insects can thus easily enter
the flower on this latter side. All the flowers on the
left side of the spike are open on their left sides, while
those on the right side are open on this side. The
twisted column with all the important accessory parts,
together with the rectangularly bent apex, closely re-
semble the corresponding parts in M. ignea. But the
under side of the labellum does not rest on and press
against the rectangularly bent apex of the column.
This stands free in the middle of a cup formed by the
extremity of the labellum.

I did not obtain many flowers fit for examination,
as three had ejected their pollinia owing to the shocks
received during their journey. I pricked deeply the
labellum, column and stigma of some of the flowers
without any effect ; but when I lightly touched with a

220 VANDE^. Chap. VII.

needle, not the anther-hinge as in the last species, but
the apex of the column of one flower, the pollinium
was instantly ejected. The bases of the petals and
sepals are not swollen and succulent like those of
M. ignea ; and I have little doubt that insects gnaw
the labellum, which is thick and fleshy, with the same
peculiar taste as in Catasetum. If an insect were to
gnaw the terminal cup, it could hardly fail to touch
the apex of the column, and then the pollinium would
swing upwards and adhere to some part of the insect's
body. The pedicels of the pollinia straighten them-
selves and the anther-cases are cast off, in about fifteen
minutes after the act of ejection. We may therefore
confidently believe that this species is fertilised in the
same peculiar manner as Mormodes ignea.

Cyenoches ventricosum. — Mr. Yeitch was so kind as to
send me on two occasions several flowers and flower-
buds of this extraordinary plant. A sketch of a
flower in its natural position, with one sepal cut off,
is shown at fig. 33 (p. 222), and a longitudinal section
through a young bud at fig. 34 (p. 223).

The labellum is thick and fleshy, with the usual
taste of this organ in the Catasetidae ; it resembles in
shape a shallow basin turned upside down. The two
other petals and the three sepals are reflexed. The
column is almost cylindrical, thin, flexible, elastic
and of extraordinary length. It curves round so
as to bring the stigma and anther opposite to and
beneath the convex surface of the labellum. The
apex of the column is not nearly so much produced as
in Mormodes and Catasetum. The pollinia closely
resemble those of Mormodes ; but the disc is larger,
and its curtain, which is fringed, is so large that it
covers the whole entrance into the stigmatic chamber.
The structure of these parts is best seen in the section ,

Chap. VII. CYCNOCHES VENTEICOSUM. 221

fig. 34 ; in which the pedicel of the polliniuni has not
as yet become separate from the rostellum, but the
future line of separation is shown by a line (dotted
in the figure) of hyaline tissue. The filament of the
anther (/, fig. 34) has not as yet grown to its full
length. When fully developed it bears two little leaf-
like appendages which lie on the anther. Lastly,
on the sides of the stigma there are two slight
protuberances (fig. 33), which apparently represent
the antenna? of Catasetum, but have not the same
function.

Neither the labellum nor the protuberances on the
sides of the stigma are at all sensitive ; but when on
three occasions I momentarily touched the filament,
between the little leaf-like appendages, the pollinium
was ejected in the same manner and through the
same mechanism as in Mormodes ; but it was thrown
only to the distance of about an inch. If the filament
had been touched by an object which had not been
quickly removed, or if by an insect, the viscid disc
would certainly have adhered to it. Mr. Veitch informs
me that he has often touched the end of the column,
and the pollinium has adhered to his finger. When
the pollinium is ejected, the pedicel forms a hoop, with
the exterior surface of the curtain of the disc resting
on and covering the anther. In about fifteen minutes
the pedicel straightens itself, and the anther-case
drops off; and now the pollinium is in a right position
for fertilising another flower. As soon as the viscid
matter on the under surface of the disc is exposed to
the air it quickly changes colour and sets hard. It
then adheres with surprising force to any object.
From these various facts and from the analogy of the
other Catasetidse, we may conclude that insects visit
the flowers for the sake of gnawing the labellum :

222

YANDEX.

Chap. VII.

but it cannot be predicted whether they alight on the
surface which is uppermost in the drawing (fig. 33) and

Fig. 33.

CYCNOCHES VENTRrCOSUM.

Flower viewed in its natural dependent position.

c. column, after the ejection of
the pollinium together with
the anther.

/. filament of anther.

s. stigmatic cavity.

L. labellum.

pet. the two lateral petals.

j sep. sepals.

then crawl over the margin so as to gnaw the convex
surface, and in doing so touch with their abdomens

Chap. VII.

CYCNOCHES VENTRICOSUM.

223

the extremity of the column, or whether they first
alight on this part of the column ; but in either case
they would cause the ejection of the pollinia, which
would adhere to some part of their bodies.

The specimens which I examined were certainly

Fig. 34.

Diagrammatic Section of a Flower-bud, the column placed
upright.

a. anther.

/. filament of anther.

p. pollen-mass.

pd. pedicel of pollinium, barely se-
parated as yet from the ros-
tellum.

d. disc of pollinium with the depen-
dent curtain.
s. stigmatic chamber.
g. stigmatic canal leading to the

male plants, for the pollinia were well developed. The
stigmatic cavity was lined with a thick layer of pulpy
matter which was not adhesive. But as the flowers
cannot possibly be fertilised until the pollinia have
been ejected, together with the great curtain which
covers the whole stigmatic surface, it may be that

224 VANDE^:. Chap. YII.

this surface becomes at a later period adhesive so as to
secure the pollen-masses. The ovules when kept for
some time in alcohol were filled with brownish pulpy
matter, as is always the case with perfect ovules.
Therefore it appears that this Cycnoches must be an
hermaphrodite ; and Mr. Bateman, in his work on the
Orchideee, says that the present species produces seeds
without being, as I understand, artificially fertilised ;
but how this is possible is unintelligible to me. On
the other hand, Beer says * that the stigma of Cyc-
noches is dry, and that the plant never sets seeds.
According to Lindley C. ventricosum produces on the
same scape flowers with a simple labellum, others with
a much segmented and differently coloured labellum
(viz., the so-called C. egertonianum), and others in an
intermediate condition. From the analogous differ-
ences in the flowers of Catasetum, we are tempted to
believe that we here have male, female, and herma-
phrodite forms of the same species of Cycnoches. t

I have now finished my description of the Catasetidse
as well as of many other Yandeae. The study of these
wonderful and often beautiful productions, with all
their maoy adaptations, with parts capable of move-
ment, and other parts endowed with something so like,
though no doubt different from, sensibility, has been to
me most interesting. The flowers of Orchids, in their
strange and endless diversity of shape, may be com-

* Quoted by Irmisoh, ' Beitrage Mr. Bnteman also says that C.

zur Biologie der Orchideen,' 1853, egertonianum lias been known to

p. 22. produce in Guatemala and once

t Lindley's ' Vegetable King- in Englnnd scapes of a purple-

dom,' 1853, p. 177. He has also flowered and widely different spe-

published in the 'Botanical Eegis- cies of Cycnoches ; but that it

ter,' fol. 1361, a case of two forms generally produces in England

appearing on the same scape of scapes of the common yellow C,

another species of Cycnoches. ventricosum.

Cuap. YII. VAJTOE.E. 225

pared with the great vertebrate class of Fish, or still
more appropriately with tropical Homopterous insects,
which appear to us as if they had been modelled
in the wildest caprice, but this no doubt is due to
our ignorance of their requirements and conditions
of life.

11

226 CTPEIFEDE^:. Chap. V1I1.

CHAPTEK VIII.

CYPRIPEDE2E— HOMOLOGIES OF THE FLOWERS OF
ORCHIDS.

Cypripedium, differs much from all other Orchids — Labellum in the
form of a slipper with two small orifices by which insects can escape
— Manner of fertilisation by small bees of the genus Andrena —
Homological nature of the several parts of the flowers of the OrchidesB
— Wonderful amount of modification which they have undergone.

We have now arrived at Lindley's last and seventh
tribe, including, according to most botanists, only a
single genus, Cypripedium, which differs from all
other Orchids far more than any other two of these
do from one another. An enormous amount of ex-
tinction must have swept away a multitude of inter-
mediate forms, and has left this single genus, now
widely distributed, as a record of a former and more
simple state of the great Orchidean Order. Cypripe-
dium possesses no rostellum ; for all three stigmas
are fully developed, though confluent. The single
anther, which is present in all other Orchids, is here
rudimentary, and is represented by a singular shield-
like projecting body, deeply notched or hollowed out
on its lower margin. There are two fertile anthers
which belong to an inner whorl, represented in ordinary
Orchids by various rudiments. The grains of pollen
are not united together by threes or fours, as in so
many other genera, nor are they tied together by
elastic threads, nor furnished with a caudicle, nor
cemented into waxy masses. The labellum is of

Chap. VIII.

CYPKIPEDIUM.

227

large size, and is a compound organ as in all other
Orchids.

The following remarks apply only to the six species
which I have examined, namely, G. harbatum, pwrpu-
ratum, insigne, venustum, pubescens and acaule ; though
I have casually looked at some other kinds. The
basal part of the labellum is folded round the short

Fig. 35.

Cypripedium.

a. anther.

a*, rudimentary, shield-like anther.

s. stigma.

I. labellum.

A. Flower viewed from above, with
the sepals and petals, excepting
the labellum, partly cut off.
The labellum has been slightly
depressed, so that the dorsal

surface of the stigma is ex-
posed ; the edges of the label-
lum have thus become a little
separated and the toe or ex-
tremity stands lower than is
natural.
B. Side view of column, with all
the sepals and petals removed.

column, so that its edges nearly meet along the dorsal
surface ; and the broad extremity is folded over in a
peculiar manner, forming a sort of shoe, which closes
up the end of the flower. Hence arises the English
name of Ladies'-slipper. The overarching edges of the
labellum are inflected or sometimes only smooth and

228 CYPRIPEDE^:. Chap. Vlll

polished internally ; and this is of much importance,
as it prevents insects which have once entered the
labellum from escaping through the great opening in
the upper surface. In the position in which the flower
grows, as here represented, the dorsal surface of the
column is uppermost. The stigmatic surface is slightly-
protuberant, and is not adhesive; it stands nearly-
parallel to the lower surface of the labellum. With a
flower in its natural state, the margin of the dorsal
surface of the stigma can be barely distinguished be-
tween the edges of the labellum and through the
notch in the rudimentary, shield-like anther (a!) ; but
in the drawing (s, fig. A) the margin of the stigma has
been brought outside the edges of the depressed la-
bellum, and the toe is a little bent downwards, so that
the flower is represented as rather more open than it
really is. The edges of the pollen-masses of the two
lateral anthers (a) can be seen through the two small
orifices or open spaces in the labellum (fig. A) on
each side, close to the column. These two orifices are
essential for the fertilisation of the flower.

The grains of pollen are coated by and immersed in
viscid fluid, which is so glutinous that it can be drawn
out into short threads. As the two anthers stand be-
hind and above the lower convex surface (see fig. B) of
the stigma, it is impossible that the glutinous pollen
can without some mechanical aid get on to this, the
efficient surface of the stigma. The economy here
shown by Nature in her manner of gaining the same
end is surprising. In all the other Orchids seen by
me, the stigma is viscid and more or less concave, by
which means the dry pollen, transported by means of
the viscid matter secreted by the rostellum or modified
stigma, is retained. In Cypripedium the pollen is
glutinous, and assumes the function of viscidity, which

Cfiap. VIII. CYPRIPEDIUM. 229

in all other Orchids except Vanilla belongs exclusively
to the rostellum and the two confluent stigmas. These
latter organs, on the other hand, in Cypripedium en-
tirely lose their viscidity, and at the same time become
slightly convex, so as more effectually to rub off the
glutinous pollen adhering to the body of an insect.
Moreover in several of the North American species,
as in G acaule and pubescens, the surface of the stigma
is beset, as Professor Asa Gray remarks, * " with
minute, rigid, sharp-pointed papillae, all directed for-
wards, which are excellently adapted to brush off the
pollen from an insect's head or back." There is one
partial exception to the above rule of the pollen of
Cypripedium being viscid while the stigma is not
viscid and is not convex ; for in C. acaule the pollen
is more granular and less viscid, according to Asa
Gray, than in the other American species, and in
G. acaule alone the stigma is slightly concave and
viscid. So that here the exception almost proves the
truth of the general rule.

I have never been able to detect nectar within the
labellum, and Kurrf makes the same remark with
respect to G. calceolus. The inner surface of the la-
bellum, however, in those species which I examined,
is clothed with hairs, the tips of which secrete little
drops of slightly viscid fluid. And these if sweet or
nutritious would suffice to attract insects. The fluid
when dried forms a brittle crust on the summits of the
hairs. Whatever the attraction may be, it is certain
that small bees frequently enter the labellum.

Formerly I supposed that insects alighted on the
labellum and inserted their proboscides through either

* 'American Journal of Science,' t 'Bedeutung der Nektarien,

vol. xxxiv. 1862, p. 428. 1833, p. 29.

230 CYPRIPEDE.E. Chap. VITI.

of the orifices close to the anthers ; for I found that
when a bristle was thus inserted the glutinous pollen
adhered to it, and could afterwards be left on the
stigma ; but this latter part of the operation was not
well effected. After the publication of my book
Professor Asa Gray wrote to me * that he was convinced
from an examination of several American species that
the flowers were fertilised by small insects entering the
labellum through the large opening on the upper sur-
face, and crawling out by one of the two small orifices
close to the anthers and stigma. Accordingly I first
introduced some flies into the labellum of G. pubescens,
through the large upper opening, but they were either
too large or too stupid, and did not crawl out properly.
I then caught and placed within the labellum a very
small bee which seemed of about the right size, namely,
Andrena parvula, and this by a strange chance proved,
as we shall presently see, to belong to the genus on
which in a state of nature the fertilisation of C. calceo-
lus depends. The bee vainly endeavoured to crawl out
again the same way by which it had entered, but always
fell backwards, owing to the margins being inflected.
The labellum thus acts like one of those conical traps
with the edges turned inwards, which are sold to catch
beetles and cockroaches in the London kitchens. It
could not creep out through the slit between the folded
edges of the basal part of the labellum, as the elongated,
triangular, rudimentary stamen here closes the passage.
Ultimately it forced its way out through one of the
small orifices close to one of the anthers, and was
found when caught to be smeared with the glutinous
pollen. I then put the same bee back into the label-
lum ; and again it crawled out through one of the small

See also ■ American Journal of Science,' vol. xxxiv. 1862, p. 427.

Chap. VIII. CYPRIPEDIUM. 231

orifices, always covered with pollen. I repeated the
operation five times, always with the same result. I
afterwards cut away the labellum, so as to examine the
stigma, and found its whole surface covered with pollen.
It should be noticed that an insect in making its escape
must first brush past the stigma and afterwards one of
the anthers, so that it cannot leave pollen on the
stigma, until being already smeared with pollen from
one flower it enters another ; and thus there will be a
good chance of cross-fertilisation between two distinct
plants. Delpino* with much sagacity foresaw that
some insect would be discovered to act in this manner ;
for he argued that if an insect were to insert its pro-
boscis, as I had supposed, from the outside through
one of the small orifices close to one of the anthers, the
stigma would be liable to be fertilised by the plant's
own pollen : and in this he did not believe, from
having confidence in what I have often insisted on —
namely, that all the contrivances for fertilisation are
arranged so that the stigma shall receive pollen from
a distinct flower or plant. But these speculations are
now all superfluous ; for, owing to the admirable ob-
servations of Dr. H. Muller, f we know that Cypri-
'pedium caleeolus in a state of nature is fertilised in the
manner just described by bees belonging to five species
of Andrena.

Thus the use of all the parts of the flower, — namely,
the inflected edges, or the polished inner sides of the
labellum, — the two orifices and their position close to
the anthers and stigma, — the large size of the medial
rudimentary stamen, — are rendered intelligible. An

* ' Fecondazione n^lle Piaiite xxv. III. Folge, v. Bd. p. 1 : see

Antocarpee,' 1867, p. 20. also 4 Befruclitung der Blumen,'

f ' Verh. d. Nat. Ver. fur Pr. 1873, p. 76.
Rheinland und Westfal.' Jalir^

232 HOMOLOGIES OF THE Chap. VIII.

insect which enters the labellum is thns compelled to
crawl out by one of the two narrow passages, on the
sides of which the pollen-masses and stigma are placed.
We have seen that exactly the same end is gained in
the case of Coryanthes by the labellum being half-
filled with secreted fluid ; and in the case of Pterostylis
and some other Australian Orchids by the labellum
being irritable, so that when touched by an entering
insect it shuts up the flower, with the exception of a
single narrow passage.*

Homological Nature of the several Parts of the Flowers of
the Orchideas.

The theoretical structure of few flowers has been so
largely discussed as that of the Orchideae ; nor is this
surprising, seeing how unlike they are to common
flowers ; and here will be a convenient place for con-
sidering this subject. No group of organic beings can
be well understood until their homologies are made
out ; that is, until the general pattern, or, as it has
often been called, the ideal type, of the several mem-
bers of the group is intelligible. No one member
may now exist exhibiting the full pattern ; but this
does not make the subject less important to the natu-
ralist,— probably makes it more important for the
full understanding of the group.

The homologies of any being, or group of beings,

* Selenipedium pdlmifolium is the fish-pot system, i. e. a funnel-
one of the Cypripedese, and shaped opening conducts into it,
according to Dr. Criigcr (4 Journ. and insects find it difficult to
Linn. Soc. Bot.' vol. viii. 1864, p. escape through the same. The
134) bears very fragrant flowers, only other opening near the base
which "in all probability are of the labellum is partly closed
always impregnated by insects. by the sexual apparatus, and the
The labellum is, like some Aris- insect has to force its way out
tolochia-flowers, construct* d after there."

Chap. VIII. FLOWERS OF ORCHIDS. 233

can be most surely made out by tracing their embryo-
logical development when that is possible ; or by the
discovery of organs in a rudimentary condition ; or by
tracing, through a long series of beings, a close gradation
from one part to another, until the two parts or organs,
though employed for widely different functions and
most unlike each other, can be joined by a succession
of short links. No instance is known of a close gradation
between two organs, unless they are homologically one
and the same organ.

The importance of the science of Homology rests on
its giving us the key-note of the possible amount of
difference in plan within any group ; it allows us to
class under proper heads the most diversified organs ;
it shows us gradations which would otherwise have
been overlooked, and thus aids us in classification ; it
explains many monstrosities ; it leads to the detection
of obscure and hidden parts, or mere vestiges of parts,
and shows us the meaning of rudiments. Besides
these uses, Homology clears away the mist from such
terms as the scheme of nature, ideal types, archetypal
patterns or ideas, &c. ; for these terms come to express
real facts. The naturalist, thus guided, sees that all
homologous parts or organs, however much they may
be diversified, are modifications of one and the same
ancestral organ ; in tracing existing gradations he
gains a clue in tracing, as far as that is possible, the
probable course of modification through which beings
have passed during a long line of generations. He
may feel assured that, whether he follows embryo-
logical development, or searches for the merest rudi-
ment, or traces gradations between the most different
beings, he is pursuing the same object by different
routes, and is tending towards the knowledge of the
actual progenitor of the group, as it once grew and

234 HOMOLOGIES OF THE Chap. VIII.

lived. Thus the subject of Homology gains largely
in interest.

Although this subject, under whatever aspect it be
viewed, will always be most interesting to the student
of nature, it is very doubtful whether the following
details on the homological nature of the flowers of
Orchids will possess any interest for the general reader.
If, indeed, he cares to see how much light an acquaint-
ance with homology, though far from perfect, throws
on a subject, this will, perhaps, be nearly as good an
instance as could be given. He will see how curiously
a flower may be moulded out of many separate organs,
— how perfect the cohesion of primordially distinct
parts may become, — how organs may be used for pur-
poses widely different from their proper uses, — how
other organs may be entirely suppressed, or leave mere
useless emblems of their former existence. Finally,
he will see how enormous has been the amount of
change which these flowers have undergone from their
parental or typical form.

Robert Brown first clearly discussed the homologies
of Orchids,* and left, as might be expected, little to
be done. Guided by the general structure of mono-
cotyledonous plants and by various considerations,
he propounded the doctrine that the flower properly
consists of three sepals, three petals, six anthers in
two whorls or circles (of which only one anther belong-
ing to the outer whorl is perfect in all the common
forms), and of three pistils, with one of them modified
into the rostellum. These fifteen organs are arranged
as usual, alternately, three within three, in five whorls.
Of the existence of three of the anthers in two of

* I believe his latest views are the ' Linnean Transactions,' vol.
given in his celebrated paper, read xvi. p. 685.
Nov. 1-15, 1831, and published in

Chap. VIII. FLOWFBS OF ORCHIDS. 235

the whorls, K. Brown offers no sufficient evidence, but
believes that they are combined with the labellum,
whenever that organ presents crests or ridges. In
these views Brown is followed by Lindley.*

Brown traced the spiral vessels in the flower by
making transverse sections, f and only occasionally, as
far as it appears, by longitudinal sections. As spiral
vessels are developed at a very early period of growth,
and this circumstance always gives much value to a
part in making out homologies ; and as they are ap-
parently of high functional importance, though their
function is not well known, it appeared to me, guided
also by the advice of Dr. Hooker, to be worth while to
trace upwards all the spiral vessels from the six groups
surrounding the ovarium. Of the six ovarian groups
of vessels, I will call (though not correctly) that under
the labellum the anterior group ; that under the
upper sepal the posterior group ; and the two groups
on the two sides of the ovarium the antero-lateral and
postero-lateral groups.

The result of my dissections is given in the following
diagram (fig. 36). The fifteen little circles represent

* Professor Asa Gray has de- the union of one petal with two

scribed in the ' American Journal petaloid stamens,

of Science.' July 1866, a monstrous f ' Linn. Transact.' vol. xvi. p.

flower of Ct/pripedium cand'dum, 696-701. Link in his ' Bemer-

and remarks on it, " here we have kungen iiber der Bau der Orchi-

(and perhaps the first direct) deen'('BotanischeZeitung,' 1849,

demonstration that the orchideous p. 745) eeems to have also trusted

type of flower has two staminal to transverse sections. Had he

verticils, as Brown always in- traced the vessels upwards I can-

sisttd." Dr. Criiger aho advances not believe that he would have

evidence ( ' Journ. Linn. Soc. disputed Brown's view of the

Bot.' vol. viii. 1861, p. 132) in nature of the two anthers in

favour of the presence of five Cypiipedium. Brongniart in his

whorls of organs ; but he denies admirable paper (' Annales des

that the homologies of the parts Sciences Nat.' torn. xxiv. 1831 )

can be deduced from the course of incidentally shows the course of

the vessels, and he does not admit some of the spiral vessels.
that the labellum is formed by

236

HOMOLOGIES OF THE

Chap. VIII.

so many groups of spiral vessels, in every case traced
down to one of the six large ovarian groups. They
alternate in five whorls, as represented ; but I have not
attempted to give the actual distances at which they
stand apart. In order to guide the eye, the three
central groups running to the three pistils are con-
nected by a triangle.

Fig. 36.
Upper or posterior sepal.

Lower
sepal.

Labellum.

Section of the Flower of an Orchid.

The little circles show the position of the spiral vessels.

SS. Stigmas; SP, stigma modified
into the rostellum.

A,. Fertile anther of the outer
whorl ; A2 A3, anthers of the
same whorl combined with
the lower petal, forming the
labellum.

ajrt2. Rudimentary anthers of the
inner whorl (fertile in Cypri-
pedium), generally forming
the clinandrum ; a3, third
anther of the same whorl,
when present, forming the
front of the column.

Five groups of vessels run into the three sepals
together with the two upper petals ; three enter the

Chap. VIII. FLOWERS OF ORCHIDS. 237

labellum ; and seven run up the great central column.
These vessels are arranged, as may be seen, in rays
proceeding from the axis of the flower ; and all on the
same ray invariably run into the same ovarian group ;
thus the vessels supplying the upper sepal, the fertile
anther (A^, and the upper pistil or stigma (i. e. the
rostellum Sr), all unite and form the posterior ovarian
group. Again, the vessels supplying, for instance, the
left lower sepals, the corner of the labellum and one
of the two stigmas (S) on the same side, unite and form
the antero-lateral group; and so with all the other
vessels.

Hence, if the existence of groups of spiral vessels
can be trusted, the flower of an Orchid certainly
consists of fifteen organs, in a much modified and
confluent condition. We see three stigmas, with the
two lower ones generally confluent, and with the upper
one modified into the rostellum. We see six stamens,
arranged in two whorls, with generally one alone (Ax)
fertile. In Cypripedium, however, two stamens of
the inner whorl (ax and a2) are fertile, and in other
Orchids these two are represented more plainly in
various ways than the remaining stamens. The third
stamen of the inner whorl (<x3), when its vessels can
be traced, forms the front of the column : Brown
thought that it often formed a medial excrescence,
or ridge, cohering to the labellum ; or, in the case of
Glossodia,* a filamentous organ, freely projecting in
front of the labellum. The former conclusion does
not agree with my dissections ; about Glossodia I
know nothing. The two infertile stamens of the outer
whorl (A2, A3) were believed by Brown to be only
occasionally represented, and then by lateral excre-

* See Brown's observations 'Plantae Asiaticae rariores,' 1830,
under Apostasia in W allien 's p. 74.

238 HOMOLOGIES OF THE Chap. VIII.

scences on the labellum ; but I find the corresponding
vessels invariably present in the labellum of every
Orchid examined, — even when the labellum is very
narrow or quite simple, as in Malaxis, Herminium,
or Habenaria.

We thus see that an Orchid-flower consists of five
simple parts, namely, three sepals and two petals ;
and of two compounded parts, namely, the column and
labellum. The column is formed of three pistils, and
generally of four stamens, all completely confluent.
The labellum is formed of one petal with two petaloid
stamens of the outer whorl, likewise completely con-
fluent. I may remark, as making this fact more
probable, that in the allied Marantaceae the stamens,
even the fertile stamens, are often petaloid, and
partially cohere. This view of the nature of the label-
lum explains its large size, its frequently tripartite
form, and especially the manner of its coherence to the
column, unlike that of the other petals.* As rudi-
mentary organs vary much, we can thus perhaps
understand the variability, which as Dr. Hooker informs
me is characteristic of the excrescences on the labellum.
In some Orchids which have a spur-like nectary, the
two sides are apparently formed by the two modified
stamens ; thus in Gymnadenia conopsea (but not in
Orchis pyramidalis), the vessels, proceeding from the
two antero-lateral ovarian groups, run down the sides
of the nectary ; those from the single anterior group
run down the exact middle of the nectary, then
returning up the opposite side form the mid-rib of the
labellum. The sides of the nectary being thus formed of
two distinct organs, apparently explains the tendency,

* Link remarks on the manner the column in his " Bemerkungen '
oF coherence of the labellum to in • Bot. Zeitung,' 1849, p. 745.

(Jhap. VIII.

FLOWERS OF ORCHIDS.

239

as in Calanthe, Orchis morio, &c, to the bifurcation of
its extremity.

The number, position, and course of all the spiral
vessels exhibited in the diagram (fig. 36) were observed
in some Vandeae and Epidendreae.* In the Malaxese

* It may be advisable to give a
few details on the flowers which
I dissected ; but I looked to special
points, such as the course of the
vessels in the labellum, in many-
cases not worth here giving. In
the Vandeae I traced all the ves-
sels in Catasetum tridentatum and
saccatum; the great group of
vessels going to the rostellum
separate (as likewise in Mormodes)
from the posterior ovarian group,
beneath the bifurcation supplying
the upper sepal and fertile anther ;
the anterior ovarian group runs
a little way along the labellum
bpfore it bifurcates and sends a
group (a3) up the front of the
column; the vessels proceeding
from the postero-lateral group run
up the back of the column, on
each side of those running to the
fertile anther, and do not go to
the edges of the clinandrum. In
Acropera luteola the ba>e of the
column, where the labellum is
attached, is much produced, and
the vessels of the whole anterior
ovarian group are similarly pro-
duced ; those (a3) going up the
front of the column are abruptly
reflected ba^k ; the vessels at the
point of reflexion are curiously
hardened, flattened, and produced
into odd crests and points. In
an Oncidium I traced the vessels
Sr to the viscid gland of the polli-
nium. Among the Epiden Irese I
traced all the vessels in a Cattleya ;
and all in Eoeh/na carivata except
a3, which I did not search for. In
the Malaxese I traced ftlliri Liparis
pendula except a3, which I do not
believe is present. In Malaxis
paludosa I traced nearly all the

vessels. la Cypripedium barbafnm
and pupuratum I traced all except
a3, which I am nearly sure does
not exist. In the Neotteae I traced
in Cephalanthera qrandljlora all
the vessels, excepting that to the
aborted rostellum and those to
the two auricles a, and a2, which
were certainly absent. In Epi~
pactis I traced all excepting a„ a2,
and a3, whh-h are certainly absent.
In Spiranthes autumnalU the
vessel Sr runs to the bottom of
the fork of the rostellum : there
are no vessels to the membranes
of the clinandrum in this Orchid
nor in Goodyera. In none of the
Ophreae do the vessels a,, a2, and
a3 Occur. In Orchis pyramid alls
I traced all the others, including
two to the two separate stigmas :
in this species the contrast between
the vessels of the labellum and
of the other sepals and petals is
striking, as in the latter the ves-
sels do not branch, whilst the
labellum has three ve>sels the
lateral ones running of course into
the antero- lateral ovarian group.
In Gymnadenia conopsea I traced
all the vessels ; but 1 am not sure
whether the vessels supplying the
sides of the upper sepal do not, as
in the allied Habenar a, wander
from their proper course and enter
the postero lateral ovarian group :
the vessel Sr, going to the rostel-
lum, enters the little folded crest
of membrane, which projects be-
tween the bases of the anther-cells.
Lastly, in Habenaria chlorantha I
traced all the vessels, excepting
as in the other Ophreae the three
of the inner staminal whorl, and I
looked carefully for a3 : the vessel

240 HOMOLOGIES OF THE Chap. VIII.

all were observed excepting a3, which is the most
difficult one to trace, and apparently is oftenest absent.
In the Cypripedeae, again, all were traced except a3*
which, I feel pretty sure, was here really absent : in
this tribe the stamen (Ax) is represented by a con-
spicuous shield-like rudiment, and ax and a2 are
developed into two fertile anthers. In the Ophrese
and Neotteae all were traced, with the important
exception of the vessels belonging to the three stamens
(a19 a2, and a3) of the inner whorl. In Cephalanthera
grandiflora, I clearly saw a3 proceeding from the
anterior ovarian group, and running up the front of
the column. This anomalous Orchid has no rostellum,
and the vessel marked Sr in the diagram was entirely
absent, though seen in every other species.

Although the two anthers (ax and a2) of the inner
whorl are not fully and normally developed in any
Orchid, excepting Cypripedium, their rudiments are
generally present and are often utilised ; for they often
form the membranous sides of the cup-like clinandrum
on the summit of the column, which includes and pro-
tects the pollen-masses. These rudiments thus aid
their fertile brother-anther. In the young flower-bud

supplying the fertile anther runs tion of a free filament in front of

up the connective membrane be- the labellum, as in the case of

tween the two anther-cells, but Glossodia before mentioned ; and

does not bifurcate : the ves-el to this will perhaps account for th&

the rostellum runs up to the top absence of spiral vessels, proceed-

of the shoulder or ledge beneath ing from the anterior ovarian

the conn> ctive membrane of the group and coalescing with the

anther, but does not bifurcate and column. In Uropedium, a genus

extend to the two widely -separated which A. Brongniart (' Annal.

viscid discs. des. Sc. Nat.,' 3rd series, Bot. torn.

* From Irmisch's ('Beitrage xiii. p. 114) considers closely allied

zur Biologie der Orchideen,' 1853, to, and even perhaps a monstro-

pp. 78 and 42) description of the sity of, Cypripedium, a third fer-

development of the flower-bud of tile anther occupies this same

Cypripedium, it would appear that position,
there is a tendency to the forma-

CHAJ. VIII. FLOWERS OF ORCHIDS. 241

of Mdlaxis paludosa, the close resemblance between the
two membranes of the clinandrum and the fertile
anther, in shape, texture, and in the height to which
the spiral vessels extended, was most striking : it was
impossible to doubt that in these two membranes we
had two rudimentary anthers. In Evelyna, one of the
EpidendreEe, the clinandrum was similarly formed, as
were the horns of the clinandrum in Masclevallia, which
serve in addition to keep the labellum at the proper
distance from the column. In Liparis pendula and
some other species, these two rudimentary anthers form
not only the clinandrum, but likewise wings, which
project on each side of the entrance into the stigmatic
cavity, and serve as guides for the insertion of the
pollen-masses. In Acropera and Stanhopea, as far as
I could make out, the membranous borders of the
column, down to its base, were also thus formed ; but
in other cases, as in Cattleya, the wing-like borders of
the column seem to be simple developments of the two
pistils. In this latter genus, as well as in Catasetum,
these same two rudimentary stamens, judging from the
position of the vessels, serve chiefly to strengthen
the back of the column ; and the strengthening of the
front of the column is the sole function of the third
stamen of the inner whorl (a3), in those cases in
which it was observed. This third stamen runs up
the middle of the column to the lower edge, or lip,
of the stigmatic cavity.

I have said that in the Ophreas and Neottese the
spiral vessels of the inner whorl, marked al9 a2, az in
the diagram, are entirely absent, and I looked care-
fully for them ; but in nearly all the members of these
two tribes, two small papillae, or auricles as they have
been often called, stand in exactly the position which
the two first of these three anthers would have occupied,

242 HOMOLOGIES OF THE Chap. VIII.

had they been developed. Not only do they stand in
this position, but the column in some cases, as in
Cephalanthera, has on each side a prominent ridge,
running from them to the bases or mid-ribs of the two
upper petals ; that is, in the proper position of the
filaments of these two stamens. It is, again, impossible
to doubt that the two membranes of the clinandrum
in Malaxis are formed by these two anthers in a
rudimentary and modified condition. Now, from the
perfect clinandrum of Malaxis, through that of Spi-
ranthes, Goodyera, Epipactis latifolia, and E. palustris
(see fig. 16, p. 101, and fig. 15, p. 94), to the minute
and slightly flattened auricles iu the genus Orchis, a
perfect gradation can be traced. Hence I conclude that
these auricles are doubly rudimentary ; that is they
are rudiments of the membranous sides of the clinan-
drum, these membranes themselves being rudiments of
the two anthers so often referred to. The absence of
spiral vessels running to the auricles is by no means
sufficient to overthrow the views here advocated as to
the much disputed nature of these structures; that
such vessels may quite disappear, we have proof in
Cephalanthera grandiflora, in which the rostellum and
its vessels are completely aborted.

Finally, then, with respect to the six stamens which
ought to be represented in every Orchid: the three
belonging to the outer whorl are always present, the
upper one being fertile (except in Cypripedium), and
the two lower ones invariably petaloid and forming
part of the labellum. The three stamens of the inner
whorl are less plainly developed, especially the lower
one, a3, which, when it can be detected, serves only to
strengthen the column, and, in some rare cases, accord-
ing to Brown, forms a separate projection or filament ;
the two upper anthers of this inner whorl are fertile

Chap. VIII. FLOWERS OF ORCHIDS. 213

in Cypripedium, and in other cases are generally-
represented either by membranous expansions, or by
minute auricles without spiral vessels. These auricles,
however, are sometimes quite absent, as in some species
of Ophrys.

On this view of the homologies of Orchid-flowers,
we can understand the existence of the conspicuous
central column, — the large size, generally tripartite
form, and peculiar manner of attachment of the la-
bellum, — the origin of the clinandrum, — the relative
position of the single fertile anther in most of the
genera, and of the two fertile anthers in Cypripedium,
— the position of the rostellum, as well as of all the
other organs, — and lastly, the frequent occurrence of a
bilobed stigma, and the occasional occurrence of two
distinct stigmas. I have encountered only one case oi
difficulty, namely in Habenaria and the allied genus,
Bonatea. These flowers have undergone such an
extraordinary amount of distortion, owing to the wide
separation of their anther-cells and of the two viscid
discs of the rostellum, that any anomaly in them is
the less surprising. The anomaly relates only to the
vessels supplying the sides of the upper sepal and
of the two upper petals ; for the vessels running into
their midribs and into all the other more important
organs pursue the same identical course as in the other
Ophrese. The vessels which supply the sides of the
upper sepal, instead of uniting with the midrib and
entering the posterior ovarian group, diverge and enter
the postero-lateral groups. Again, the vessels on the
anterior side of the two upper petals, instead of uniting
with those of the midrib and entering the postero-
lateral ovarian groups, diverge, or wander from their
proper course, and enter the antero-lateral groups.

This anomaly is so far of importance, as it throws

244 HOMOLOGIES OF THE Chap. VIII.

some doubt on the view that the labellum is always
an organ compounded of one petal and two petaloid
stamens ; for if any one were to assume that from some
unknown cause the lateral vessels of the lower petals
had diverged in an early progenitor of the Orchidean
order from their proper course into the antero-lateral
ovarian groups, and that this structure had been in-
herited by all existing Orchids, even by those with the
smallest and simplest labellums, I could answer only
as follows ; but the answer is, I think, satisfactory.
From the analogy of other monocotyledonous plants,
we might expect the hidden presence of fifteen organs
in the flowers of the Orchidese, arranged alternately
in five whorls; and in these flowers we find fifteen
groups of vessels exactly thus arranged. Hence there
is a strong probability that the vessels, A2 and A3,
which enter the sides of the labellum, not in one or
two cases, but in all the Orchids seen by me, and which
occupy the precise position which they would have
occupied had they supplied two normal stamens, do
really represent modified and petaloid stamens, and
are not lateral vessels of the labellum which have
wandered from their proper course. In Habenaria and
Bonatea,* on the other hand, the vessels proceeding

* In Bonatea speciosa, of which ments of the two upper petals

I have examined only dry speci- cohere with the labellum, causing

mens sent me by Dr. Hooker, the it to have five segments, which is

vessels from the sides of the upper a most unusual fact. The two

sepal enter the postero-lateral wonderfully protuberant stigmas

ovarian group, exactly as in also cohere to the upper surface of

Habenaria. The two upper petals the labellum ; and the lower sepals

are divided down to their bases, apparently also cohere to its under

and the vessels supplying the side. Consequently a section of

anterior segment and those supply- the base of the labellum divides

ing the anterior portion of the one lower petal, two petaloid

posterior segment unite and then anthers, portions of the two upper

run, as in Habenaria, into the petals, and apparently of the two

antero-lateral (and therefore lower sepals and the two stigmas :

wrong) group. The anterior seg- altogether the section passes

Chap. VIII. FLOWERS OF ORCHIDS. 245

from the sides of the upper sepal and of the two upper
petals, which enter the wrong ovarian groups, cannot
possibly represent any lost but once distinct organs.

We have now finished with the general homologies
of the flowers of Orchids. It is interesting to look at
one of the magnificent exotic species, or, indeed, at
one of our humblest forms, and observe how profoundly
it has been modified, as compared with all ordinary
flowers, — with its great labellum, formed of one petal
and two petaloid stamens, — with its singular pollen-
masses, hereafter to be referred to, — with its column
formed of seven cohering organs, of which three alone
perform their proper function, namely, one anther and
two generally confluent stigmas, — with the third stigma
modified into the rostellum and incapable of being
fertilised, — and with three of the anthers no longer
functionally active, but serving either to protect the
pollen of the fertile anther, or to strengthen the column,
or existing as mere rudiments, or entirely suppressed.
What an amount of modification, cohesion, abortion,
and change of function do we here see ! Yet hidden
in that column, with its surrounding petals and sepals,
we know that there are fifteen groups of vessels,
arranged three within three, in alternate order, which
probably have been preserved to the present time from
being developed at a very early period of growth,
before the shape or existence of any part of the flower
is of importance for the well-being of the plant.

Can we feel satisfied by saying that each Orchid was
created, exactly as we now see it, on a certain " ideal
type ; " that the omnipotent Creator, having fixed on
one plan for the whole Order, did not depart from this

through the whole of or through is here as complex anortran as the
portions of either seven or nine column of other Orchids,
organs. The base of the labellum

246 HOMOLOGIES. Chap. VIII.

plan ; that he, therefore, made the same organ to per-
form diverse functions — often of trifling importance
compared with their proper function — converted other
organs into mere purposeless rudiments, and arranged
all as if they had to stand separate, and then made
them cohere ? Is it not a more simple and intelligible
view that all the Orchidese owe what they have in
common, to descent from some monocotyledonous
plant, which, like so many other plants of the same
class, possessed fifteen organs, arranged alternately
three within three in five whorls ; and that the now
wonderfully changed structure of the flower is due to
a long course of slow modification, — each modification
having been preserved which was useful to the plant,
during the incessant changes to which the organic
and inorganic world has been exposed ?

Chap. IX. GRADATION OF ORGANS. 247

CHAPTER IX.

GRADATION OF ORGANS, &C. — CONCLUDING REMARKS.

Gradation of organs, of the rostellum, of the pollen-masses — Formation
of the caudicle— Genealogical affinities — Secretion of nectar —
Mechanism of the movement of the pollinia — Uses of the petals —
Production of seed — Importance of trifling details of structure —
Cause of the great diversity of structure in the flowers of Orchids
— Cause of the perfection of the contrivances — Summary on insect-
agency — Nature abhors perpetual self-fertilisation.

This chapter will be devoted to the consideration of
several miscellaneous subjects which could not well
have been introduced elsewhere.

On the gradation of certain Organs. — The rostellum,
the pollinia, the labellum, and, in a lesser degree,
the column, are the most remarkable points in the
structure of Orchids. The formation of the column
and labellum, by the confluence and partial abortion of
several organs, has been discussed in the last chapter.
With respect to the rostellum, no such organ exists
in any other group of plants. If the homologies of
Orchids had not been pretty well made out, those
who believe in the separate creation of each organism
might have advanced this as an excellent instance of
a perfectly new organ having been specially created,
and which could not have been developed by suc-
cessive slow modifications of any pre-existing part.
But, as Eobert Brown long ago remarked, it is not a
new organ. It is impossible to look at the two groups
of spiral vessels (fig. 36) running from the bases of

248 GRADATION OF ORGANS. Chap. IX.

the midribs of the two lower sepals to the two lower
stigmas, which are sometimes quite distinct, and then
to look at the third group of vessels running from the
base of the mid-rib of the upper sepal to the rostellum,
which occupies the exact position of a third stigma,
and doubt its homological nature. There is every
reason to believe that the whole of this upper stigma,
and not merely a part, has been converted into the
rostellum ; for there are plenty of cases of two stigmas,
but not one of three stigmatic surfaces being present
in those Orchids which have a rostellum. On the
other hand, in Cypripedium and Apostasia (the latter
ranked by Brown in the Orchidean order), which are
destitute of a rostellum, the stigmatic surface is trifid.
As we know only those plants which are now living,
it is impossible to follow all the gradations by which
the upper stigma has been converted into the rostellum ;
but let us see what are the indications of such a change
having been effected. With respect to function the
change has not been so great as it at first appears.
The function of the rostellum is to secrete viscid matter,
and it has lost the capacity of being penetrated by
the pollen-tubes. The stigmas of Orchids, as well as
of most other plants, secrete viscid matter, the use of
which is to retain the pollen when brought to them by
any means, and to excite the growth of the pollen-
tubes. Now if we look to one of the simplest rostel-
lums, — for instance, to that of Cattleya or Epidendrum,
— we find a thick layer of viscid matter, not distinctly
separated from the viscid surface of the two confluent
stigmas : its use is simply to affix the pollen-masses to
a retreating insect, which are thus dragged out of the
anther and transported to another flower, where they
are retained by the almost equally viscid stigmatic
surface. So that the office of the rostellum is still to

Cuap. IX. GRADATION OF ORGANS. 249

secure the pollen-masses, but indirectly by means of
their attachment to an insect's body.

The viscid matter of the rostellum and of the
stigma appear to have nearly the same nature ; that
of the rostellum generally has the peculiar property of
quickly drying or setting hard ; that of the stigma,
when removed from the plant, apparently dries more
quickly than gum-water of about equal density or
tenacity. This tendency to dry is the more remarkable,
as Gartner * found that drops of the stigmatic secre-
tion from Nicotiana did not dry in two months. The
viscid matter of the rostellum in many Orchids when
exposed to the air changes colour with remarkable
quickness, and becomes brownish-purple ; and I have
noticed a similar but slower change of colour in the
viscid secretion of the stigmas of some Orchids, as of
Cephalanthera grandijlora. When the viscid disc of an
Orchis, as Bauer and Brown have observed, is placed
in water, minute particles are expelled with violence
in a peculiar manner ; and I have observed exactly
the same fact in the layer of viscid matter covering
the stigmatic utriculi in an unopened flower of Mor-
modes ignea.

In order to compare the minute structure of the
rostellum and stigma, I examined young flower-buds
of Epidendrum coehleatum and floribundum, which, when
mature, have a simple rostellum. The posterior parts
of both organs were quite similar. The whole of
the rostellum at this early age consisted of a mass
of nearly orbicular cells, containing spheres of brown
matter, which resolve themselves into the viscid fluid.
The stigma was covered with a thinner layer of similar
cells, and beneath them were the coherent spindle-

Beitr'age zur Kenntniss der Befrucbtung/ 1814, p. 236.
12

250 GRADATION OF ORGANS. Chap. IX.

formed utriculi. These are believed to be connected
with the penetration of the pollen-tubes; and their
absence in the rostellum probably accounts for its
not being penetrated. If the structure of the ros-
tellum and of the stigma is as here described, their
only difference consists in the layer of cells which
secrete the viscid matter being thicker in the ros-
tellum than in the stigma, and in the utriculi having
disappeared from the former. There is therefore no
great difficulty in believing that the upper stigma,
whilst still in some degree fertile or capable of pene-
tration by the pollen-tubes, might have gradually
acquired the power of secreting a larger amount of
viscid matter, losing at the same time its capacity for
fertilisation ; and that insects smeared with this viscid
matter removed and transported the pollen-masses in
a more and more effective manner to the stigmas of
other flowers. In this case an incipient rostellum
would have been formed.

In the several tribes, the rostellum presents a
marvellous amount of diversity of structure ; but most
of the differences can be connected without very wide
breaks. One of the most striking differences is, that
either the whole anterior surface to some depth, or
only the internal parts become viscid ; and in this
latter case the surface retains, as in Orchis, a mem-
branous condition. But these two states graduate
into each other so closely, that it is scarcely possible
to draw any line of separation between them : thus,
in Epipactis, the exterior surface undergoes a vast
change from its early cellular condition, for it becomes
converted into a highly elastic and tender membrane,
which is in itself slightly viscid, and allows the under-
lying viscid matter readily to exude ; yet it acts as a
membrane, and its under surface is lined with much

Chap. IX. GRADATION OF ORGANS. 251

more viscid matter. In Habenaria chlorantha the
exterior surface is highly viscid, but still closely re-
sembles, under the microscope, the exterior membrane
of Epipactis. Lastly, in some species of Oncidium,
&c, the exterior surface, which is viscid, differs, as far
as appearance under the microscope goes, from the
underlying viscid layer only in colour; but it must
have some essential difference, for I find that, until
this very thin exterior layer is disturbed, the under-
lying matter remains viscid; but, after it has been
disturbed, the underlying matter rapidly sets hard.
The gradation in the state of the surface of the ros-
tellum is not surprising, for in all cases the surface is
cellular in the bud; so that an early condition has
only to be retained more or less perfectly.

The nature of the viscid matter differs remarkably
in different Orchids : in Listera it sets hard almost
instantly, more quickly than plaster of Paris ; in
Malaxis and Angrseeum it remains fluid for several
days ; but these two states pass into each other by
many gradations. In an Oncidium I have observed
the viscid matter to dry in a minute and a half; in
some species of Orchis in two or three minutes ; in
Epipactis in ten minutes ; in Gymnadenia in two
hours ; and in Habenaria in over twenty-four hours.
After the viscid matter of Listera has set hard, neither
water nor weak spirits of wine has any effect on it ;
whereas that of Habenaria bifolia, after having been
dried for several months, when moistened became as
adhesive as ever it was. The viscid matter in some
species of Orchis, when remoistened, presented an
intermediate condition.

One of the most important differences in the state
of the rostellum is, whether or not the pollinia are
permanently attached to it. I do not allude to those

252 GRADATION OF ORGANS. Chap. IX.

cases in which the upper surface of the rostellum is
viscid, as in Malaxis and some Epidendrums, and
simply adheres to the pollen-masses ; for these cases
present no difficulty. But I refer to the so-called con-
genital attachment of the pollinia by their caudicles
to the rostellum or viscid disc. It is not, however,
strictly correct to speak of congenital attachment, for
the pollinia are invariably free at an early period, and
become attached either earlier or later in different
Orchids. No actual gradation is at present known in
the process of attachment ; but it can be shown to
depend on very simple conditions and changes. In
the Epidendrese the pollinia consist of a ball of waxy
pollen, with a long caudicle (formed of elastic threads
with adherent pollen-grains), which never becomes
spontaneously attached to the rostellum. In some of
the Vandeae, as in Cymbidium giganteum, on the other
hand, the caudicles are congenitally (in the above
sense) attached to the pollen-masses, but their struc-
ture is the same as in the Epidendrese, with the sole
difference, that the extremities of the elastic threads
adhere to, instead of merely lying on, the upper lip of
the rostellum.

In a form allied to Cymbidium, namely, Oncidium
unguiculatum, I studied the development of the cau-
dicles. At an early period the pollen-masses are
enclosed in membranous cases, which soon rupture at
one point. At this early period, a layer of rather
large cells, including remarkably opaque matter, may
be detected within the cleft of each pollen-mass. This
matter can be traced as it gradually changes into a
translucent substance which forms the threads of the
caudicles. As the change progresses, the cells them-
selves disappear. Finally the threads at one end ad-
here to the waxy pollen-masses, and at the other end

Chap. IX. GRADATION OF ORGANS. 253

after protruding through a small opening in the mem-
branous case in a semi-developed state, they adhere
to the rostellum, against which the anther is pressed.
So that the adhesion of the caudicle to the back of the
rostellum seems to depend solely on the early rupturing
of the anther-case, and on a slight protrusion of the
caudicles, before they have become fully developed and
hardened.

In all the Orchideae a portion of the rostellum is
removed by insects when the pollinia are removed ; for
the viscid matter, though conveniently spoken of as a
secretion, is in fact part of the rostellum in a modified
condition. But in those species which have their
caudicles attached at an early period to the rostellum,
a membranous or solid portion of its exterior surface in
an unmodified condition is likewise removed. In the
Vandeae this portion is sometimes of considerable size
(forming the disc and pedicel of the pollinium), and
gives to their pollinia their remarkable character ; but
the differences in the shape and size of the removed
portions of the rostellum can be finely graduated to-
gether, even within the single tribe of the Vandeae ;
and still more closely by commencing with the minute
oval atom of membrane to which the caudicle of Orchis
adheres, passing thence to that of Hdbenaria hifolia, to
that of H. chlorantha with its drum -like pedicel, and
thence through many forms to the great disc and
pedicel of Catasetum.

In all the cases in which a portion of the exterior
surface of the rostellum is removed together with the
caudicles of the pollen-masses, definite and often com-
plicated lines of separation are formed, so as to allow
of the easy separation of the removed portions. But,
the formation of these lines of separation does not
differ much from the process by which certain portions

254 GRADATION OF ORGANS. Chap. IX,

of the exterior surface of the rostellum assume a con-
dition intermediate between that of unaltered mem-
brane and of viscid matter, which has been already
alluded to. The actual separation of portions of the
rostellum depends in many cases on the excitement
from a touch ; but how a touch thus acts is at present
inexplicable. Such sensitiveness in the stigma to a
touch (and the rostellum, as we know, is a modified
stigma), and indeed in almost every other part, is by
no means a rare quality in plants.

In Listera and Neottea, if the rostellum is touched,
even by a human hair, two points rupture and the
loculi containing the viscid matter instantly expel it.
Here we have a case towards which as yet no gradation
is known. But Dr. Hooker has shown that the ros-
tellum is at first cellular, and that the viscid matter
is developed within the cells, as in other Orchids.

The last difference which I will mention in the
state of the rostellum of various Orchids is the exist-
ence in many Ophreae of two widely-separated viscid
discs, sometimes included in two separate pouches.
Here it appears at first sight as if there were two
rostella ; but there is never more than one medial
group of spiral vessels. In the Vandeae we can see
how a single viscid disc and a single pedicel might
become divided into two ; for in some Stanhopeas the
heart-shaped disc shows a trace of a tendency to divi-
sion; and in Angraecum we have two distinct discs
and two pedicels, either standing close together or
removed only a little way apart.

It might be thought that a similar gradation from a
single rostellum into what appears like two distinct ros-
tella was shown still more plainly in the Ophreae ; for
we have the following series, — in Orchis pyramidalis a
single disc enclosed in a single pouch — in Aceras two

Chap. IX. GRADATION OF ORGANS. 255

discs touching and affecting each other's shapes, but
not actually joined — in Orchis latifolia and maculata
two quite distinct discs but with the pouch still
showing plain traces of division ; and, lastly, in
Ophrys we have two perfectly distinct pouches, in-
cluding of course two perfectly distinct discs. But
this series does not indicate the former steps by which
a single rostellum became divided into two distinct
organs ; on the contrary, it shows how the rostel
lum, after having been anciently divided into two
organs, has now in several cases been reunited into
a single organ.

This conclusion is founded on the nature of the little
medial crest, sometimes called the rostellate process,
between the bases of the two anther-cells (see fig. 1,
B and D, p. 8). In both divisions of the Ophrese —
namely the species having naked discs and those
having discs enclosed in a pouch — whenever the two
discs come into close juxta-position, this medial crest
or process appears.* On the other hand, when the two
discs stand widely apart, the summit of the rostellum
between them is smooth, or nearly smooth. In the
Frog Orchis (Peristylus viridis) the overarching sum-
mit is bent like the roof of a house ; and here we see
the first stage in the formation of the folded crest. In
Herminium monorchis, however, which has two separate
and large discs, a crest, or solid ridge, is rather more
plainly developed than might have been expected.
In Gymnadenia conopsea, Orchis maculata, and others,
the crest consists of a hood of thin membrane ; in

* Professor Babington ('Manual from the other genera of Ophrese.

of British Botany,' 3rd edit.) uses The group of spiral vessels, pro-

the existence of this " rostellate perly belonging to the rostellum,

process " as a character to separate runs up, and even into, the base

Orchis, Gymnadenia, and Aceras of this crest or process.

256 GRADATION OF ORGANS. Chap. IX.

0. mascula the two sides of the hood partly adhere ;
and in 0. jpyramidalis and in Aceras it is converted
into a solid ridge. These facts are intelligible only
on the view, that, whilst the two discs were gradually
brought together, during a long series of generations,
the intermediate portion or summit of the rostellum
became more and more arched, until a folded crest,
and finally a solid ridge was formed.

Fig. 37.

Rostellum of Catasetum.

an. antennae of rostellum. I ped. pedicel of rostellum, to which

d. viscid disc. the pollen-masses are attached.

Whether we compare together the state of the ros-
tellum in the various tribes of the Orchideae, or com-
pare the rostellum with the pistil and stigma of an
ordinary flower, the differences are wonderfully great.
A simple pistil consists of a cylinder surmounted by
a small viscid surface. Now, see what a contrast the
rostellum of Catasetum, when dissected from all the
other elements of the column, presents ; and as I
traced all the vessels in this Orchid, the drawing may
be trusted as approximately accurate. The whole organ

Ohap. IX. GRADATION OF ORGANS. 257

has lost its normal function of being fertilised. Its
shape is most singular, with the upper end thickened,
bent over and produced into two long tapering and
sensitive antennae, each of these being hollow within,
like an adder's fang. Behind and between the bases
of these antennae we see the large viscid disc, attached
to the pedicel ; the latter differs in structure from the
underlying portion of the rostellum, and is separated
from it by a layer of hyaline tissue, which spontaneously
dissolves when the flower is mature. The disc, attached
to the surrounding parts by a membrane which ruptures
as soon as it is excited by a touch, consists of strong
upper tissue, with an underlying elastic cushion,
coated with viscid matter; and this again in most
Orchids is overlaid by a film of a different nature.
What an amount of specialisation of paits do we
here behold ! Yet in the comparatively few Orchids
described in this volume, so many and such plainly-
marked gradations in the structure of the rostellum
have been described, and such plain facilities for the
conversion of the upper pistil into this organ, that, we
may well believe, if we could see every Orchid which
has ever existed throughout the world, we should find
all the gaps in the existing chain, and every gap in
in many lost chains, filled up by a series of easv
transitions.

We now come to the second great peculiarity in the
Orchideae, namely their pollinia. The anther opens
early, and often deposits the naked masses of pollen on
the back of the rostellum. This action is prefigured
in Canna, a member of a family nearly related to the
Orchideae, in which the pollen is deposited on the pistil,
close beneath the stigma. In the state of the pollen
there is great diversity : in Cypripedium and Vanilla

258

GRADATION OF ORGANS.

Chap. IX.

single grains are embedded in a glutinous fluid ; in
all the other Orchids seen by me (except the degraded
Cephalanthera) the grains are united three or four
together.* These compound grains are tied one to
the other by elastic threads, but they often form
packets which are tied together in like manner, or
they are cemented into the so-called waxy masses.
The waxy masses graduate in the Epidendreae and
VandeaB from eight to four, to two, and, by the co-
hesion of the two, into a single mass. In some of the
Epidendrese we have both kinds of pollen within the
same anther, namely, large waxy masses, and caudicles
formed of elastic threads with numerous compound
grains adhering to them.

I can throw no light on the nature of the cohesion
of the pollen in the waxy masses ; when they are
placed in water for three or four days, the compound
grains readily fall apart ; but the four grains of which
each is formed still firmly cohere ; so that the nature
of the cohesion in the two cases must be different.
The elastic threads by which the packets of pollen are

* In several eases I have ob-
served four tubes emitted from
the tour grains which form one of
the compound grains. In some
semi-monsti ous flowers of Malaxis
paludosa, and of Aceras anthropo-
phora, and in perfect flowers of
A'eottia nidus-avis, I have observed
tubes emitted from the pollen-
grains, whilst still within the
anther and not in contact with
the stigma. I have thought th'S
worth mentioning as R. Brown
(' Linn. Transact.' vol. xvi. p. 729)
states, apparently witli s-orae sur-
prise, that the pollen-tubes w* re
emitted from the pollen, whilst
still within the anther, in a decay-
ing flower of Asclepias. These
cases show that the protruding

tubes are, at least at first, formed
exclusively at the expense of the
contents of the pollen -grains.

Having alluded to the monstrous
flowers of the Aceras, I will add
that I examined several (always
the lowest on the spike) in which
the labellum was hardly developed,
and was pressed close against the
stigma. The rnstellum was not
developed, so that the pollinia did
not possess viscid discs ; but the
most curious feature was, that the
two anther-cells had become, appa-
rently in consequence of the posi-
tion of the rudimentary labellum.
widely separated, and were joined
by a connective membrane, almost
as broad as that of Habenariu
chlorantha J

Chap. IX. GRADATION OF ORGANS. 259

tied together in the Ophreae, and which run far up
inside the waxy masses of the Vandeae, are also of a
different nature from the cementing matter ; for the
threads are acted on by chloroform and by long im-
mersion in spirits of wine ; whilst these fluids have no
particular action on the cohesion of the waxy masses.
In several Epidendreae and Vandeae the exterior grains
of the pollen-masses differ from the interior grains, in
being larger, and in having yellower and much thicker
walls. So' that in the contents of a single anther-cell
we see a surprising degree of differentiation in the
pollen, namely, grains cohering by fours, then being
either tied together by threads or cemented together
into solid masses, with the exterior grains different
from the interior ones.

In the Vandeae, the caudicle, which is composed of
fine coherent threads, is developed from the semi-fluid
contents of a layer of cells. As I find that chloroform
has a peculiar and energetic action on the caudicles
of all Orchids, and likewise on the glutinous matter
which envelopes the pollen-grains in Cypripedium,
and which can be drawn out into threads, we may
suspect that in this latter genus, — the least differenti-
ated in structure of all the Orchideae, — we see the
primordial condition of the elastic threads by which
the pollen-grains are tied together in other and more
highly developed species.*

* Auguste de Saint Hilaire drop by drop into the anther.

('Lecons de Botanique,' &c, 1841, Had not so eminent an authority

p. 447) says that the elastic threads made this statement, I should not

exist in the early bud, after the have noticed it. It is certainly

pollen-grains have been partly erroneous. In buds of Epipactu

formed, as a thick creamy fluid. latifolia I opened the anther,

He adds that his observations on whilst perfectly closed and free

Ophrys apifera have shown him from Ihe rostellum, and found the

that this fluid is secreted by the pollen-grains united by elastic

rostellum, and is slowly forced threads. Cevhalanthera grandi-

260 GRADATION OF ORGANS. Chap. IX

The caudicle, when largely developed and destitute
of pollen-grains, is the most striking of the many pecu-
liarities presented by the pollinia. In some Neotteae,
especially in Goodyera, we see it in a nascent con-
dition, projecting just beyond the pollen-mass, with
the threads only partially coherent. In the Yandese
by tracing the gradation from the ordinary naked
condition of the caudicle, through Lycaste in which
it is almost naked, through Calanthe, to Cymbidium
giganteum, in which it is covered with pollen-grains, it
seems probable that its ordinary condition has been
arrived at by the modification of a pollinium like
that of one of the Epidendrege ; namely, by the abor-
tion of the pollen-grains which primordially adhered to
separate elastic threads, and afterwards by the cohesion
of these threads.

In the Ophrese we have better evidence than is
afforded by gradation, that their long, rigid and
naked caudicles have been developed, at least partially,
by the abortion of the greater number of the lower
pollen-grains and by the cohesion of the elastic threads
by which these grains were tied together. I had often
observed a cloudy appearance in the middle of the
translucent caudicles in certain species ; and on care-
fully opening several caudicles of Orchis pyramidalis,
I found in their centres, fully half-way down between
the packets of pollen and the viscid disc, many pollen-
grains (consisting, as usual, of four united grains),

Hora has no rostellum to secrete and stigma ; yet I found in one

the above thick fluid, yet the of these auricles a distinct caudicle

pollen-grains are thus united. In (which necessarily had no disc at

a monstrous specimen of Orchis its extremity), and this caudicle

pyramidalis the auricles, or rudi- could not possibly have been

meatary anthers on each side of secreted by the rostellum 01

the proper anther, had become stigma. I could advance addi

partly developed, and they stood tional evidence, but it would be

quite on one side of the rostellum superfluous.

Chap. IX. GRADATION OF ORGANS. 261

lying quite loose. These grains, from their embedded
position, could never by any possibility have been left
on the stigma of a flower, and were absolutely useless.
Those who can persuade themselves that purposeless
organs have been specially created, will think little of
this fact. Those on the contrary, who believe in the
slow modification of organic beings, will feel no
surprise that the changes have not always been per-
fectly effected, — that, during and after the many
inherited stages of the abortion of the lower pollen-
grains and of the cohesion of the elastic threads,
there should still exist a tendency to the production
of a few grains where they were originally developed ;
and that these should consequently be left entangled
within the now united threads of the caudicle. They
will look at the little clouds formed by the loose
pollen-grains within the caudicles of Orchis jpyramidalis,
as good evidence that an early progenitor of this plant
had pollen-masses like those of Epipactis or Goodyera,
and that the grains slowly disappeared from the lower
parts, leaving the elastic threads naked and ready to
cohere into a true caudicle.

As the caudicle plays an important part in the
fertilisation of the flower, it might have been deve-
loped from one in a nascent condition, such as we see
in Epipactis, to any required length merely by the
continued preservation of varying increments in its
length, each beneficial in relation to other changes in
the structure of the flower, and without any abortion
of the lower pollen-grains. But we may conclude
from the facts just given, that this has not been the
sole means, — that the caudicle owes much of its length
to such abortion. That in some cases it has subse-
quently been largely increased in length by natural
selection, is highly probable; for in Bonatea speeiosa

262 LINES OF DESCENT. Chap. IX.

the caudicle is actually more than thrice as long as the
elongated pollen-masses ; and it is highly improbable
that so lengthy a mass of grains, slightly cohering
together by the aid of elastic threads, should ever have
existed, as an insect could not have safely transported
and applied a mass of this shape and size to the
stigma of another flower.

We have hitherto considered gradations in the state
of the same organ. To any one with more knowledge
than I possess, it would be an interesting subject to
trace the gradations between the several species and
groups of species in this great and closely-connected
order. But to make a perfect gradation, all the extinct
forms which have ever existed, along many lines of
descent converging to the common progenitor of the
group, would have to be called back into life. It is
due to their absence, and to the consequent wide gaps
in the series, that we are enabled to divide the exist-
ing species into definable groups, such as genera,
families, and tribes. If there had been no extinction,
there would still have been great lines or branches of
special development, — the Yandese, for instance, would
still have been distinguishable as a great body, from
the great body of the Ophreae ; but ancient and inter-
mediate forms, very different probably from their
present descendants, would have rendered it utterly
impossible to separate by distinct characters the one
great body from the other.

I will venture on only a few more remarks. Cypri-
pedium, in having three stigmas developed, and there-
fore in not possessing a rostellum, in having two fertile
anthers with a large rudiment of a third, and in the
state of its pollen, seems a remnant of the order whilst
in a simpler or more generalised condition. Apostasia

Chap. IX. LINES OF DESCENT. 263

is a related genus, placed by Brown amongst the
Orchideae, but by Lindley in a small distinct family.
These broken groups do not indicate to us the structure
of the common parent-form of all the Orchideae, but
they serve to show the probable state of the order in
ancient times, when none of the forms had become so
widely differentiated from one another and from other
plants, as are the existing Orchids, especially the
Vandeae and Ophreae ; and when, consequently, the
order made a nearer approach in all its characters,
than it does at present, to such allied groups as the
Marantaceae.

With respect to other Orchids, we can see that an
ancient form, like one of the sub-tribe of the Pleuro-
thallidae, some of which have waxy pollen-masses with
a minute caudicle, might have given rise, by the entire
abortion of the caudicle, to the Dendrobiae, and by an
increase of the caudicle to the Epidendreae. Cymbi-
dium shows us how simply a form like one of our
present Epidendreae could be modified into one of the
Yandeae. The Neotteae stand in nearly a similar relation
to the higher Ophreae, which the Epidendreae do to the
higher Vandeae. In certain genera of the Neotteae we
have compound pollen-grains cemented into packets
and tied together by elastic threads, which project and
thus form a nascent caudicle. But this caudicle does
not protude from the lower end of the pollinium as in
the Ophreae, nor does it always protrude from the ex-
treme upper end in the Neotteae, but sometimes at an
intermediate level ; so that a transition in this respect
is far from impossible. In Spiranthes, the back of the
rostellum, lined with viscid matter, is alone removed :
the front part is membranous, and ruptures like the
pouch-formed rostellum of the Ophreae. An ancient
form combining most of the characters, but in a less

264 LINES OF DESCENT. Chap. IX.

developed state, of Goodyera, Epipactis, and Spiranthes,
all members of the Neotteae, could by further slight
modifications have given birth to the tribe of the
Ophreae.

Hardly any question in Natural History is more
vague and difficult to answer than what forms ought
to be considered as the highest in a large group ; * for
all are well adapted to their conditions of life. If we
look to successive modifications, with differentiation of
parts and consequent complexity of structure, as the
standard of comparison, the Ophreae and Yandeae will
stand the highest among the Orchideae. Are we to lay
much stress on the size and beauty of the flower, and
on the size of the whole plant ? if so, the Yandeae are
pre-eminent. They have, also, rather more complex
pollinia, with the pollen-masses often reduced to two.
The rostellum, on the other hand, has apparently been
more modified from its primordial stigmatic nature in
the Ophreae, than in the Yandeae. In the Ophreae the
stamens of the inner whorl are almost entirely sup-
pressed,— the auricles — mere rudiments of rudiments —
being alone retained ; and even these are sometimes
lost. These stamens, therefore, have suffered extreme
reduction ; but can this be considered as a sign of
highness? I should doubt whether any member of
the Orchidean order has been more profoundly modified
in its whole structure than Bonatea speciGsa, one of the
Ophreae. So again, within this same tribe, nothing
can be more perfect than the contrivances in Orchis
pyramidalis for its fertilisation. Yet an ill -defined
feeling tells me to rank the magnificent Yandeae as
the highest. When we look within this tribe at the

* The fullest and the most able his ' Entwickelungs-Gesetze der
discussion on this difficult subject Organischen Welt,' 1858.
s by Professor H. G. Bronn in

Chap. IX. SECRETION OF NECTAR. 265

elaborate mechanism for the ejection and transportal
of the pollinia of Catasetum, with the sensitive ros-
tellum so wonderfully modified, with the sexes borne
on distinct plants, we may perhaps give the palm of
victory to this genus.

SECRETION OF NECTAR.

Many Orchids, both our native species and the
exotic kinds cultivated in our hothouses, secrete a
copious supply of nectar. I have found the horn-like
nectaries of Aerides filled with fluid ; and Mr. Kodgers,
of Sevenoaks, informs me that he has taken crystals
of sugar of considerable size from the nectary of A.
cornutum. The nectar-secreting organs of the Orchidese
present great diversities of structure and position in
the various genera ; but are almost always situated
towards the base of the labellum. In Disa, however,
the posterior sepal alone, and in Disperis the two
lateral sepals together with the labellum, secrete
nectar. In Dendrdbium chrysanthum the nectary
consists of a shallow saucer ; in Evelyna, of two large
united cellular balls ; and in Bolbophyllum cupreum, of
a medial furrow. In Cattleya the nectary penetrates
the ovarium. In Angrsecum sesquipedale it attains the
astonishing length of above eleven inches ; but I need
not enter on further details. The fact, however,
should be recalled, that in Coryanthes the nectar-
secreting glands pour forth an abundance of almost
pure water, which drips into a bucket formed by the
distal part of the labellum ; and this secretion serves
to prevent the bees which come to gnaw the surface of
the labellum from flying away, and thus compels them
to crawl out through the proper passage.

Although the secretion of nectar is of the highest

266 SECKETION OF NECTAR. Chap. IX.

importance to Orchids by attracting insects, which are
indispensable for the fertilisation of most of the species,
yet good reasons can be assigned for the belief* that
nectar was aboriginally an excretion for the sake of
getting rid of superfluous matter during the chemical
changes which go on in the tissues of plants, especially
whilst the sun shines. The bracteae of some Orchids
have been observed t to secrete nectar, and this cannot
be of any use to them for their fertilisation. Fritz
Muller informs me that he has seen such secretion
from the bracteae of an Oncidium in its native Bra-
zilian home, as well as from the bracteae and from the
outside of the upper sepal of a Notylia. Mr. Kodgers
has observed a similar and copious secretion from the
base of the flower-peduncles of Vanilla. The column
of Acropera and Gongora likewise secretes nectar, as
previously stated, but only after the flowers have been
impregnated, and when such secretion could be of no
use by attracting insects. It is in perfect accordance
with the scheme of nature, as worked out by natural
selection, that matter excreted to free the system from
superfluous or injurious substances should be utilised
for highly useful purposes. To give an example in
strong contrast with our present subject, the larvae of
certain beetles (Cassidae, &c.) use their own excrement
to make an umbrella-like protection for their tender
bodies.

It may be remembered that evidence was given in
the first chapter proving that nectar is never found
within the spur-like nectaries of several species of
Orchis, but that various kinds of insects penetrate

* This subject has been fully 1876, p. 402.

discussed in my work ' On the f Kurr, ' Ueber die Bedeutung

Effects of Cross and Self-fertilisa- der Nektarien,' 1833, p. 28.
tion in the Vegetable Kingdom,'

Chap. IX. SECRETION OF NECTAR. 267

the tender inner coat with their proboscides, and suck
the fluid contained in the inter-cellular spaces. This
conclusion has been confirmed by Hermann Miiller,
and I have further shown that even Lepidoptera are
able to penetrate other and tougher tissues. It is an
interesting case of co-adaptation that in all the British
species, in which the nectary does not contain free
nectar, the viscid matter of the disc of the pollinium
requires a minute or two in order to set hard ; and
it would be an advantage to the plant if insects were
delayed thus long in obtaining the nectar by having
to puncture the nectary at several points. On the
other hand, in all the Ophreae which have nectar ready
stored within the nectary, the discs are sufficiently
viscid for the attachment of the pollinia to insects,
without the matter quickly setting hard; and there
would therefore be no advantage to these plants in
insects being delayed for a few minutes whilst sucking
the flowers.

In the case of cultivated exotic Orchids which have
a nectary, without any free nectar, it is of course
impossible to feel absolutely sure that it would not
contain any under more natural conditions. Nor have
I made many comparative observations on the rate of
the setting hard of the viscid matter of the disc in
exotic forms. Nevertheless it seems that some Vandeoe
are in the same predicament as our British species of
Orchis ; thus Calanthe masuca has a very long nectary,
which in all the specimens examined by me was quite
dry internally, and was inhabited by powdery Cocci ;
but in the intercellular spaces between the two coats
there was much fluid ; and in this species the viscid
matter of the disc, after its surface had been disturbed,
entirely lost its adhesiveness in two minutes. In an
Oncidium the disc, similarly disturbed, became dry in

268 SECRETION OF NECTAR. Chap. IX.

one minute and a half ; in an Odontoglossum in two
minutes; and in neither of these Orchids was there
any free nectar. On the other hand, in Angrascum,
sesquipedale, which has free nectar stored within the
lower end of the nectary, the disc of the pollinium,
when removed from the plant and with its surface
disturbed, was strongly adhesive after forty-eight
hours.

SarcantJius teritifolius offers a more curious case.
The disc quite lost its viscidity and set hard in less
than three minutes. Hence it might have been ex-
pected that no fluid would have been found in the
nectary, but only in the intercellular spaces ; never-
theless there was fluid in both places, so that here we
have both conditions combined in the same flower. It
is probable that insects would sometimes rapidly suck
the free nectar and neglect that between the two
coats; but even in this case I strongly suspect that
they would be delayed by a totally different means
in sucking the free nectar, so as to allow the viscid
matter to set hard. In this plant, the labellum with
its nectary is an extraordinary organ. I wished to
have had a drawing made of its structure ; but found
that it was as hopeless as to give a drawing of the
wards of a complicated lock. Even the skilful Bauer,
with numerous figures and sections on a large scale,
hardly makes the structure intelligible. So com-
plicated is the passage, that I failed in repeated
attempts to pass a bristle from the outside of the
flower into the nectary ; or in a reversed direction
from the cut-off end of the nectary to the outside. No
doubt an insect with a voluntarily flexible proboscis
could pass it through the passages, and thus reach
the nectar ; but in effecting this, some delay would
be caused ; and time would be thus allowed for the

Chap. IX. SECRETION OF NECTAR. 269

curious square viscid disc to become securely cemented
to an insect's head or body.

As in Epipactis the cup at the base of the labellum
serves as a nectar-receptacle, I expected to find that
the analogous cups in Stanhopea, Acropera, &c, would
serve for the same purpose ; but I could never find
a drop of nectar in them. According, also, to M.
Meniere and Mr. Scott * this is never the case in these
genera, or in Gongora, Cirrhsea, and many others. In
Catasetum tridentatum, and in the female form Mona-
chanthus, we see that the upturned cup cannot
possibly serve as a nectar-receptacle. What then
attracts insects to these flowers ? That they must be
attracted is certain ; more especially in the case of Cata-
setum, in which the sexes stand on separate plants. In
many genera of Vandese there is no trace of any nectar-
secreting organ or receptacle ; but in all these cases
(as far as I have seen), the labellum is either thick and
fleshy, or is furnished with extraordinary excrescences,
as in the genera Oncidium and Odontoglossum. In
Phaltenopsis grandiflora there is a curious anvil-shaped
projection on the labellum, with two tendril-like pro-
longations from its extremity which turn backwards
and apparently serve to guard the sides of the anvil, so
that insects would be forced to alight on its crown.
Even in our British Cephalanthera grandiflora, the
labellum of which never contains nectar, there are
orange-coloured ribs and papillae on the inner surface
which faces the column. In Calanthe (fig. 26) a cluster
of odd little spherical warts projects from the labellum,
and there is an extremely long nectary, which does
not include nectar ; in Eulophia viridis the short nec-
tary is equally destitute of nectar, and the labellum

Bulletin Bot. Sec. de France,' torn. ii. 1855, p. 352.

270 SECRETION OF NECTAR. Chai\ IX.

is covered with, longitudinal, fimbriated ridges. In
several species of Ophrys, there are two small shining
protuberances, at the base of the labellum, beneath the
two discs. Innumerable other cases could be added of
the presence of singular and diversified excrescences
on the labellum ; and Lindley remarks that their use
is quite unknown.

From the position, relatively to the viscid discs,
which these excrescences occupy, and from the absence
of any free nectar, it formerly seemed to me highly
probable that they afforded food and thus attracted
either Hymenoptera or flower-feeding Coleoptera.
There is no more inherent improbability in a flower
being habitually fertilised by an insect coming to
feed on the labellum, than in seeds being habitually
disseminated by birds attracted by the sweet pulp in
which they are embedded. But I am bound to state
that Dr. Percy, who had the thick and furrowed
labellum of a Warrea analysed for me by fermentation
over mercury, found that it gave no evidence of con-
taining more saccharine matter than the other petals.
On the other hand, the thick labellum of Catasetum
and the bases of the upper petals of Mormodes ignea,
have a slightly sweet, rather pleasant, and nutritious
taste. Nevertheless, it was a bold speculation that
insects were attracted to the flowers of various Orchids
in order to gnaw the excrescences or other parts of
their labella ; and few things have given me more
satisfaction than the full confirmation of this view by
Dr. Criiger, who* has repeatedly witnessed in the West
Indies humble-bees of the genus Euglossa gnawing the
labellum of Catasetum, Coryanthes, Gongora, and
Stanhopea. Fritz Miiller also has often found, in

* ' Journ. Linn. Soc. Bot.' 1864, vol. viii. p. 129.

Chap. IX. MOVEMENTS OF THE POLLINIA. 271

South Brazil, the prominences on the labellum of
Oncidium gnawed. We are thus enabled to under-
stand the meaning of the various extraordinary crests
and projections on the labellum of many Orchids ; for
they invariably stand in such a position that insects,
whilst gnawing them, would be almost sure to touch
the viscid discs of the pollinia and thus remove them,
afterwards effecting the fertilisation of another flower.

MOVEMENTS OF THE POLLINIA.

The pollinia of many Orchids undergo a movement
of depression, after they have been removed from their
places of attachment and have been exposed for a few
seconds to the air. This is due to the contraction of a
portion, sometimes to an exceedingly minute portion,
of the exterior surface of the rostellum, which retains
a membranous condition. This membrane, as we have
seen, is likewise sensitive to a touch, so as to rupture
in certain definite lines. In a Maxillaria the middle
part of the pedicel, and in Habenaria the whole drum-
like pedicel contracts. The point of contraction in all
the other cases seen by me, is either close to the
surface of attachment of the caudicle to the disc, or at
the point where the pedicel is united to the disc ; but
both the disc and pedicel are parts of the exterior
surface of the rostellum. In these remarks I do not
refer to the movements which are simply due to the
elasticity of the pedicel, as in the Vandese.

The long strap-formed disc of Gymnadenia eouopsea
is well adapted to show the mechanism of the move-
ment of depression. The whole pollinium, both in its
upright and depressed (but not closely depressed)
position, has been shown (p. 65) in fig. 10. The disc,
in its uncontracted condition with the caudicle removed,

272 MOVEMENTS OF THE POLLINIA. Chap. IX.

is seen from above highly magnified in the upper of
the two adjoining figures ; and in the lower figure we
have a longitudinal section of the uncontracted disc,
together with the base of the attached and upright
caudicle. At the broad end of the disc there is a deep
crescent-shaped depression, bordered by a slight ridge
formed of longitudinally elon-
gated cells. The end of the
caudicle is attached to the
steep sides of this depression
and ridge. When the disc is
exposed to the air for about
thirty seconds, the ridge con-
tracts and sinks flat down ; in

Disc otGymnadeniacmopsca. ^^ ft dmgg ^ ^ ^

caudicle, which then lies parallel to the elongated
tapering part of the disc. If placed in water the
ridge rises, re-elevating the caudicle, and when re-
exposed to the air it sinks again, but each time with
somewhat enfeebled power. During each sinking and
rising of the caudicle, the whole pollinium is of course
depressed and elevated.

That the power of movement lies exclusively in the
surface of the disc is well shown in the case of the
saddle-shaped disc of Orchis pyramidalis ; for whilst it
was held under water I removed the attached caudicles
and the layer of viscid matter from the inferior surface,
and immediately that the disc was exposed to the air
the proper contraction ensued. The disc is formed of
several layers of minute cells,, which are best seen in
specimens that have been kept in spirits of wine,
for their contents are thus rendered more opaque. The
cells in the flaps of the saddle are a little elongated.
As long as the saddle is kept damp, its upper surface
is nearly flat, but when exposed to the air (see fig. 3,

Chap. IX. MOVEMENTS OF THE POLLINIA. 273

E, p. 18) the two flaps or sides contract and curl inwards ;
and this causes the divergence of the pollinia. By a
kind of contraction two valleys are likewise formed in
front of the caudicles, so that the latter are thrown
forwards and downwards, almost in the same way as if
trenches were dug in front of two upright poles, and
then carried on so as to undermine them. As far as I
could perceive, an analogous contraction causes the
depression of the pollinia in Orchis mascula. With 0.
hircina both pollinia are attached to a single rather large
square disc, the whole front of which, after exposure
to the air, sinks down and is then separated from the
hinder part by an abrupt step. By this contraction both
pollinia are carried forwards and downwards.

Some pollinia which had been gummed on card for
several months, when placed in water, rose up and
afterwards underwent the movement of depression.
A fresh pollinium, on being alternately damped and
exposed to the air, rises and sinks several times alter-
nately. Before I had ascertained these facts, which
show that the movement is simply hygrometric, I
thought that it was a vital action, and tried vapour
of chloroform and of prussic acid, and immersion in
laudanum; but these reagents did not check the
movement. Nevertheless, there are some difficulties
in understanding how the movement can be simply
hygrometric. The flaps of the saddle in Orchis pyra-
midalis (see fig. 3, D, p. 18) curl completely inwards
in nine seconds, which is a surprisingly short time
for mere evaporation to produce an effect ;* and the

* This fact does not now appear awn of Stipa twists and untwists

to me so surprising as it formerly when exposed to dry and danup air.

did, for my son Francis has shown These movements being due, as

(' Transact. Linn. Soc.' 2nd series, he has shown, to the twisting and

Bot. vol. i. 1S76, p. 149) with untwisting of the separate cells,
what extraordinary quickness tho
13

274 CONCLUDING REMARKS. Chap IX.

movement is apparently due to the drying of the under
surface, although this is covered with a thick layer
of viscid matter. The edges, however, of the saddle
might become slightly dry in the nine seconds. When
the saddle-formed disc is placed in spirits of wine it
contracts energetically ; and this is probably due to
the attraction of alcohol for water. When replaced in
water it opens again. Whether or not the contraction
is wholly hygrometric, the movements are admirably
regulated in each species, so that the pollen-masses,
when transported by insects from flower to flower,
assume a proper position for striking the stigmatic
surface.

These various movements would be quite useless,
unless the pollinia were attached in a uniform position
to the insects which visit the flowers so as to be always
directed in the same manner after the movement of
depression ; and this necessitates that the insects should
be forced to visit the flowers of the same species in
a uniform manner. Hence I must say a few words
on the sepals and petals. Their primary function, no
doubt, is to protect the organs of fructification in the
bud. After the flower is fully expanded, the upper
sepal and two upper petals often continue the same
office. We cannot doubt that this protection is of
service, when we see in Stelis the sepals so neatly re-
closing and reprotecting the flower some time after its
expansion ; in Masdevallia the sepals are permanently
soldered together, with two little windows alone left
open ; and in the open and exposed flowers of Bol-
bophyllum, the mouth of the stigmatic chamber
after a time closes. Analogous facts with respect to
Malaxis, Cephalanthera, &c, could be given. But the
hood formed by the upper sepal and two upper petals,
besides affording protection, evidently forms a guide,

Chap IX. CONCLUDING REMARKS. 275

compelling insects to visit the flowers in front. Few
persons now doubt the correctness of C. K. Sprengel's
view, * that the bright and conspicuous colours of
(lowers serve to attract insects from a distance. Never-
theless some Orchids have singularly inconspicuous
and greenish flowers, perhaps in order to escape some
danger ; but many of these are strongly scented, which
would equally well serve to attract insects.

The labellum is by far the most important of the
external envelopes of the flower. It not only secretes
nectar, but is often modelled into variously shaped
receptacles for holding this fluid, or is itself rendered
attractive so as to be gnawed by insects. Unless the
flowers were by some means rendered attractive, most
of the species would be cursed with perpetual sterility.
The labellum always stands in front of the rostellum,
and its outer portion often serves as a landing-place
for the necessary visitors. In Epijpactis palusiris this
part is flexible and elastic, and apparently compels
insects in retreating to brush against the rostellum.
In Cypripedium the distal portion is folded over like
the end of a slipper, and compels insects to crawl out
of the flower by one of two special passages. In Ptero-
stylis and a few other Orchids the labellum is irritable,
so that when touched it shuts the flower, leaving only
a single passage by which an insect can escape. In
Spiranthes, when the flower is fully mature, the column
moves from the labellum, space being thus left for

* This author's curious work, own observations, that his work
with its quaint title of ' Das Ent- contains an immense bo^y of
deckte Geheimniss der Natur/ truth. Many years ago Robert
until lately was often spoken Brown, to whose judgment all
lightly of. No doubt he was an botanists defer, spoke highly of it
enthusiast, and perhaps carried to me, and remarked that only
some of his ideas to an extreme those who knew little of the sub-
length. But I feel sure, from my ject would laugh at him.

276 CONCLUDING REMARKS. Chap. IX.

the introduction of the pollen-masses attached to the
proboscis of a humble-bee. In Mormodes ignea the
labellum is perched on the summit of the column,
and here insects alight and touch a sensitive point,
causing the ejection of the pollen-masses. The la-
bellum is often deeply channelled, or has guiding
ridges, or is pressed closely against the column ; and
in a multitude of cases it approaches closely enough
to render the flower tubular. By these several means
insects are forced to brush against the rostellum. We
must not, however, suppose that every detail of struc-
ture in the labellum is of use : in some instances, as
with Sarcanthus, its extraordinary shape seems to be
partly due to its development in close apposition to
the curiously shaped rostellum.

In Listera ovata the labellum stands far from the
column, but its base is narrow, so that insects are led
to stand exactly beneath the middle of the rostellum,
In other cases, as in Stanhopea, Phalasnopsis, Gongora,
&c, the labellum is furnished with upturned basal
lobes, which manifestly act as lateral guides. In some
cases, as in Malaxis, the two upper petals are curled
backwards so as to be out of the way ; in other cases
as in Acropera, Masdevallia, and some Bolbophylluins,
these upper petals plainly serve as lateral guides, com-
pelling insects to visit the flowers directly in front of
the rostellum. In other cases, wings formed by the
margins of the clinandrum or of the column, serve as
lateral guides, both in the withdrawal of the pollinia
and in their subsequent insertion into the "stigmatic
cavity. So that there can be no doubt that the petals,
sepals and rudimentary anthers do good service in
several ways, besides affording protection to the bud.

The final end of the whole flower, with all its parts,
is the production of seed ; and these are produced by

Chap. IX CONCLUDING REMARKS. 277

Orchids in vast profusion. Not that such profusion
is anything to boast of; for the production of an almost
infinite number of seeds or eggs, is undoubtedly a sign
of lowness of organisation. That a plant, not being
an annual, should escape extinction, chiefly by the
production of a vast number of seeds or seedlings,
shows a poverty of contrivance, or a want of some
fitting protection against other dangers. I was curious
to estimate the number of seeds produced by some
few Orchids ; so I took a ripe capsule of Cephalanthera
grandiflora, and arranged the seeds on a long ruled
line as equably as I could in a narrow hillock ; and
then counted the seeds in an accurately measured
length of one-tenth of an inch. In this way the con-
tents of the capsule were estimated at 6020 seeds, and
very few of these were bad ; the four capsules borne
by the same plant would have therefore contained
24,080 seeds. Estimating in the same manner the
smaller seeds of Orchis maculata, I found the number
nearly the same, viz., 6200 ; and, as I have often seen
above thirty capsules on the same plant, the total
amount would be 186,300. As this Orchid is perennial,
and cannot in most places be increasing in number,
one seed alone of this large number yields a mature
plant once in every few years.

To give an idea what the above figures really mean,
I will briefly show the possible rate of increase of 0.
maculata : an acre of land would hold 174,240 plants,
each having a space of six inches square, and this
would be just sufficient for their growth ; so that,
making the fair allowance of 400 bad seeds in each
capsule, an acre would be thickly clothed by the pro-
geny of a single plant. At the same rate of increase,
the grandchildren would cover a space slightly exceed-
ing the island of Anglesea ; and the great grand-

278 CONCLUDING REMARKS. Chap. IX.

children of a single plant would nearly (in the ratio of
47 to 50) clothe with one uniform green carpet the
entire surface of the land throughout the globe. But
the number of seeds produced by one of our common
British orchids is as nothing compared to that of some
of the exotic kinds. Mr. Scott found that the capsule
of an Acropera contained 371,250 seeds ; and judging
from the number of flowers, a single plant would some-
times yield about seventy-four millions of seeds.
Fritz Muller found 1,756,440 seeds in a single capsule
of a Maxillaria ; and the same plant sometimes bore
half-a-dozen such capsules. I may add that by
counting the packets of pollen (one of which was broken
up under the microscope) I estimated that the number
of pollen-grains, each of which emits its tube, in a
single anther of Orchis maseula was 122,400. Amici*
estimated the number in 0. morio at 120,300. As
these two species apparently do not produce more
seed than the allied 0. maculata, a capsule of which
contained 6200 seeds, we see that there are about
twenty pollen-grains for each ovule. According to
this standard, the number of pollen-grains in the
anther of a single flower of the Maxillaria which
yielded 1,756,440 seeds must be prodigious.

What checks the unlimited multiplication of the
Orchidese throughout the world is not known. The
minute seeds within their light coats are well fitted
for wide dissemination ; and I have several times
observed seedlings springing up in my orchard and in
a newly-planted wood, which must have come from a
considerable distance. This was especially the case
with Epipactis latifolia ; and an instance has been re-
corded by a good observer f of seedlings of this plant

* MoM, 'The Vegetable Cell,* f Mr. Bree, in 'Loudon's Ma<*.

translated by Henfrey, p. 133. of Nat. Hist,' vol. ii. 1829, p. 70.

Chap. IX. CONCLUDING REMARKS. 279

appearing at the distance of between eight and ten
miles from any place where it grew. Notwithstanding
the astonishing number of seeds produced by Orchids,
it is notorious that they are sparingly distributed ; for
instance, Kent appears to be the most favourable county
in England for the order, and within a mile of my
house nine genera, including thirteen species, grow ;
but of these one alone, Orchis morio, is sufficiently
abundant to make a conspicuous feature in the vege-
tation ; as is 0. maculata in a lesser degree in open
woodlands. Most of the other species, though not
deserving to be called rare, are sparingly distributed ;
yet, if their seeds or seedlings were not largely de-
stroyed, any one of them would immediately cover the
whole land. In the tropics the species are very much
more numerous; thus Fritz Muller found in South
Brazil more than thirteen kinds belonging to several
genera growing on a single Cedrela tree. Mr. Fitz-
gerald has collected within the radius of one mile of
Sydney in Australia no less than sixty-two species, of
which fifty-seven were terrestrial. Nevertheless the
number of individuals of the same species is, I believe,
in no country nearly so great as that of very many
other plants. Lindley formerly estimated that there
were in the world about 6000 species of Orchideae,
included in 433 genera.*

The number of the individuals which come to
maturity does not seem to be at all closely determined
by the number of seeds which each species produces ;
and this holds good when closely related forms are
compared. Thus Ophrys apifera fertilises itself and
every flower produces a capsule ; but the individuals
of this species are not so numerous in some parts of

Gardener's Citron/ 1862, p. 192.

280 CONCLUDING REMARKS. Chap. IX.

England as those of 0. muscifera, which cannot fer-
tilise itself and is imperfectly fertilised by insects, so
that a large proportion of the flowers drop off unim-
pregnated. Ophrys aranifera is found in large numbers
in Liguria, yet Delpino estimates that not more than
one out of 3000 flowers produces a capsule.* Mr.
Cheeseman saysf that with the New Zealand Ptero-
stylis trullifolia much less than a quarter of the flowers,
which are beautifully adapted for cross-fertilisation,
yield capsules ; whereas with the allied Acianthus
sinclairii, the flowers of which equally require insect-
aid for their fertilisation, seventy-one capsules were
produced by eighty-seven flowers ; so that this plant
must produce an extraordinary number of seeds ; never-
theless in many districts it is not at all more abundant
than the Pterostylis. Mr. Fitzgerald, who in Aus-
tralia has particularly attended to this subject, remarks
that every flower of Thelymitra carnea fertilises itself
and produces a capsule ; yet it is not nearly so common
as Acianthus fornieatus, " the majority of the flowers
of which are unproductive. Phajus grandifolius and
Calanthe veratrifolia grow in similar situations. Every
flower of the Phajus produces seeds, only occasionally
one of the Calanthe, yet Phajus is rare and Calanthe
common."

The frequency with which throughout the world
members of various Orchideous tribes fail to have their
flowers fertilised, though these are excellently con-
structed for cross-fertilisation, is a remarkable fact.
Fritz Miiller informs me that this holds good in the
luxuriant forests of South Brazil with most of the
Epidendreae, and with the genus Vanilla. For instance,

* 'Ult. Osservaz. sulla Dico- f Transact. New Zealand Inst/

gamia,' part i. p. 177. yoI. vii. 1875, p. 351.

Chap. IX. CONCLUDING REMARKS. 281

he visited a site where Vanilla creeps over almost every
tree, and although the plants had been covered with
flowers, yet only two seed-capsules were produced. So
again with an Epidendrum, 233 flowers had fallen off
unimpregnated and only one capsule had been formed ;
of the still remaining 136 flowers, only four had their
pollinia removed. In New South Wales Mr. Fitzgerald
does not believe that more than one flower out of a
thousand of Dendrobium speciosum sets a capsule ; and
some other species there are very sterile. In New
Zealand over 200 flowers of Coryanthes triloba yielded
only five capsules ; and at the Cape of Good Hope only
the same number were produced by 78 flowers of Disa
grandiflora. Nearly the same result has been observed
with some of the species of Ophrys in Europe. The
sterility in these cases is very difficult to explain. It
manifestly depends on the flowers being constructed
with such elaborate care for cross-fertilisation, that they
cannot yield seeds without the aid of insects. From
the evidence which I have given elsewhere * we may
conclude that it would be far more profitable to most
plants to yield a few cross -fertilised seeds, at the
expense of many flowers dropping off unimpregnated,
rather than produce many self-fertilised seeds. Profuse
expenditure is nothing unusual under nature, as we see
with the pollen of wind-fertilised plants, and in the
multitude of seeds and seedlings produced by most
plants in comparison with the few that reach maturity.
In other cases the paucity of the flowers that are im-
pregnated may be due to - the proper insects having
become rare under the incessant changes to which the
world is subject ; or to other plants which are more

* ■ The Effects of Cross and Self-fertilisation in the Vegetable
Kingdom,' 1876.

282 CONCLUDING REMARKS. Chap. IX.

highly attractive to the proper insects having increased
in number. We know that certain Orchids require
certain insects for their fertilisation, as in the cases be-
fore given of Vanilla and Sarcochilus. In Madagascar
Angrsecum sesquipe&ale must depend on some gigantic
moth. In Europe Gypripedium calceolus appears to be
fertilised only by small bees of the genus Andrena,
and Epipadis latifolia only by wasps. In those cases
in which only a few flowers are impregnated owing to
the proper insects visiting only a few, this may be a
great injury to the plant ; and many hundred species
throughout the world have been thus exterminated ;
those which survive having been favoured in some
other way. On the other hand, the few seeds which
are produced in these cases will be the product of
cross-fertilisation, and this as we now positively know
is an immense advantage to most plants.

I have now nearly finished this volume, which is
perhaps too lengthy. It has, I think, been shown that
the Orchideae exhibit an almost endless diversity of
beautiful adaptations. When this or that part has been
spoken of as adapted for some special purpose, it must
not be supposed that it was originally always formed
for this sole purpose. The regular course of events
seems to be, that a part which originally served for one
purpose, becomes adapted by slow changes for widely
different purposes. To give an instance: in all the
Ophrese, the long and nearly rigid caudicle manifestly
serves for the application of the pollen-grains to the
stigma, when the pollinia are transported by insects
to another flower ; and the anther opens widely in
order that the pollinium should be easily withdrawn ;
but in the Bee Ophrys, the caudicle, by a slight in-
crease in length and decrease in its thickness, and by

Chap. IX. CONCLUDING REMARKS. 283

the anther opening a little more widely, becomes
specially adapted for the very different purpose of
self-fertilisation, through the combined aid of the
weight of the pollen-mass and the vibration of the
flower when moved by the wind. Every gradation
between these two states is possible, — of which we have
a partial instance in 0 aranifera.

Again, the elasticity of the pedicel of the pollinium
in some Yandese is adapted to free the pollen-masses
from their anther-cases ; but by a further slight modi-
fication, the elasticity of the pedicel becomes specially
adapted to shoot out the pollinium with considerable
force so as to strike the body of the visiting insect.
The great cavity in the labellum of many Vandese
is gnawed by insects and thus attracts them; but
in Mormodes ignea it is greatly reduced in size, and
serves in chief part to keep the labellum in its new
position on the summit of the column. From the
analogy of many plants we may infer that a long
spur-like nectary is primarily adapted to secrete and
hold a store of nectar ; but in many Orchids it has so
far lost this function, that it contains fluid only in the
intercellular spaces. In those Orchids in which the
nectary contains both free nectar and fluid in the inter-
cellular spaces, we can see how a transition from the
one state to the other could be effected, namely, by
less and less nectar being secreted from the inner
membrane, with more and more retained within the
intercellular spaces. Other analogous cases could be
given.

Although an organ may not have been originally
formed for some special purpose, if it now serves for
this end, we are justified in saying that it is specially
adapted for it. On the same principle, if a man were
to make a machine for some special purpose, but were

284 CONCLUDING KEMARKS. Chap. IX

to use old wheels, springs, and pulleys, only slightly
altered, the whole machine, with all its parts, might be
said to be specially contrived for its present purpose.
Thus throughout nature almost every part of each living
being has probably served, in a slightly modified con-
dition, for diverse purposes, and has acted in the living
machinery of many ancient and distinct specific forms.

In my examination of Orchids, hardly any fact has
struck me so much as the endless diversities of structure,
— the prodigality of resources, — for gaining the very
same end, namely, the fertilisation of one flower by
pollen from another plant. This fact is to a large ex-
tent intelligible on the principle of natural selection.
As all the parts of a flower are co-ordinated, if slight
variations in any one part were preserved from being
beneficial to the plant, then the other parts would
generally have to be modified in some corresponding
manner. But these latter parts might not vary at all,
or they might not vary in a fitting manner, and these
other variations, whatever their nature might be, which
tended to bring all the parts into more harmonious
action with one another, would be preserved by natural
selection.

To give a simple illustration : in many Orchids the
ovarium (but sometimes the foot-stalk) becomes for a
period twisted, causing the labellum to assume the
position of a lower petal, so that insects can easily
visit the flower; but from slow changes in the form
or position of the petals, or from new sorts of insects
visiting the flowers, it might be advantageous to the
plant that the labellum should resume its normal
position on the upper side of the flower, as is actually
the case with Malaxis paludosa, and some species of
Catasetum, &c. This change, it is obvious, might be
simply effected by the continued selection of varieties

CnAP. IX CONCLUDING REMARKS. 285

which had their ovaria less and less twisted, but if
the plant only afforded varieties with the ovarium
more twisted, the same end could be attained by the
selection of such variations, until the flower was
turned completely round on its axis. This seems to
have actually occurred with Malaxis paludosa, for
the labellum has acquired its present upward posi-
tion by the ovarium being twisted twice as much as
is usual.

Again, we have seen that in most Vandeae there is
a plain relation between the depth of the stigmatic
chamber and the length of the pedicel, by which the
pollen-masses are inserted ; now if the chamber became
slightly less deep from any change in the form of the
column or other unknown cause, the mere shortening
of the pedicel would be the simplest corresponding
change ; but if the pedicel did not happen to vary in
shortness, the slightest tendency to its becoming bowed
from elasticity as in Phalsenopsis, or to a backward
hygrometric movement as in one of the Maxillarias,
would be preserved, and the tendency would be con-
tinually augmented by selection ; thus the pedicel, as
far as its action is concerned, would be modified in
the same manner as if thad been shortened. Such
processes carried on during many thousand generations
in various ways, would create an endless diversity of
co-adapted structures in the several parts of the flower
for the same general purpose. This view affords, I
believe, the key which partly solves the problem of the
vast diversity of structure adapted for closely analogous
ends in many large groups of organic beings.

The more I study nature, the more I become
impressed with ever-increasing force, that the con-
trivances and beautiful adaptations slowly acquired
through each part occasionally varying in a slight

286 CONCLUDING REMARKS. Chap. IX.

degree but in many ways, with the preservation of those
variations which were beneficial to the organism under
complex and ever- varying conditions of life, transcend
in an incomparable manner the contrivances and
adaptations which the most fertile imagination of man
could invent.

The use of each trifling detail of structure is far
from a barren search to those who believe in natural
selection. When a naturalist casually takes up the
study of an organic being, and does not investigate
its whole life (imperfect though that study will ever
be), he naturally doubts whether each trifling point
can be of any use, or indeed whether it be due to any
general law. Some naturalists believe that number-
less structures have been created for the sake of mere
variety and beauty, — much as a workman would make
different patterns. I, for one, have often and often
doubted whether this or that detail of structure in
many of the Orchidese and other plants could be of
any service ; yet, if of no good, these structures could
not have been modelled by the natural preservation of
useful variations; such details can only be vaguely
accounted for by the direct action of the conditions of
life, or the mysterious laws of correlated growth.

To give nearly all the instances of trifling details
of structure in the flowers of Orchids, which are cer-
tainly of high importance, would be to recapitulate
almost the whole of this volume. But I will recall
to the reader's memory a few cases. I do not here refer
to the fundamental framework of the plant, such as
the remnants of the fifteen primary organs arranged
alternately in the five whorls ; for almost everyone who
believes in the gradual evolution of species will admit
that their presence is due to inheritance from a remote
parent-form. Innumerable facts with respect to the

Chap. IX. CONCLUDING REMARKS. 2S7

uses of the variously shaped and placed petals and
sepals have been given. So again, the importance of
as light difference in the shape of the caudicle of the
pollinium of the Bee Ophrys, compared with that of
the other species of the same genus, has likewise been
referred to; to this might be added the doubly-bent
caudicle of the Fly Ophrys. Indeed, the important
relation of the length and shape of the caudicle, with
reference to the position of the stigma, might be cited
throughout many whole tribes. The solid projecting
knob of the anther in Epipaetis palustris, which does
not include pollen, liberates the pollen-masses when it
is moved by insects. In Cephalanthera grandiflora, the
upright position of the almost closed flower protects
the slightly coherent pillars of pollen from disturb-
ance. The length and elasticity of the filament of the
anther in certain species of Dendrobium apparently
serves for self-fertilisation, if insects fail to transport
the pollen-masses. The slight forward inclination of
the crest of the rostelluin in Listera prevents the
anther-case being caught as soon as the viscid matter
is ejected. The elasticity of the lip of the rostelluin
in Orchis causes it to spring up again when only one
of the pollen-masses has been removed, thus keeping
the second viscid disc ready for action, which otherwise
would be wasted. No one who had not studied Orchids
would have suspected that these and very many other
small details of structure were of the highest importance
to each species ; and that consequently, if the species
were exposed to new conditions of life, and the structure
of the several parts varied ever so little, the smallest
details of structure might readily be acquired through
natural selection. These cases afford a good lesson of
caution with respect to the importance of apparently
trifling particulars of structure in other organic beings.

288 CONCLUDING REMARKS. Chap. IX,

It may naturally be inquired, Why do the Orchideaa
exhibit so many perfect contrivances for their fertili-
sation? From the observations of various botanists
and my own, I am sure that many other plants offer
analogous adaptations of high perfection ; but it seems
that they are really more numerous and perfect with
the OrchideaB than with most other plants. To a
certain extent this inquiry can be answered. As each
ovule requires at least one, probably several, pollen-
grains,* and as the seeds produced by Orchids are so
inordinately numerous, we can see that it is necessary
that large masses of pollen should be left on the stigma
of each flower. Even in the Neottese, which have
granular pollen, with the grains tied together by weak
threads, I have observed that considerable masses of
pollen are generally left on the stigmas. This cir-
cumstance apparently explains why the grains cohere
in packets or large waxy masses, as they do in so
many tribes, namely, to prevent waste in the act of
transportal. The flowers of most plants produce pollen
enough to fertilise several flowers, so as to allow of or to
favour cross-fertilisation. But with the many Orchids
which produce only two pollen-masses, and with some of
the Malaxese which produce only one, the pollen from
a single flower cannot possibly fertilise more than two
flowers or only a single one ; and cases of this kind
do not occur, as I believe, in any other group of
plants. If the Orchideae had elaborated as much
pollen as is produced by other plants, relatively to the
number of seeds which they yield, they would have
had to produce a most extravagant amount, and this
would have caused exhaustion. Such exhaustion is
avoided by pollen not being produced in any great

* Gartner, ' Beitr'age zur Kenntni^s der Befruchtung,' 1844, p. 135.

Chap. IX. CONCLUDING REMAKKS. 289

superfluity owing to the many special contrivances for
its safe transportal from plant to plant, and for placing
it securely on the stigma. Thus we can understand
why the Orchideae are more highly endowed in their
mechanism for cross-fertilisation, than are most other
plants.

In my work on the "Effects of Cross and Self
Fertilisation in the Vegetable Kingdom," I have shown
that when flowers are cross-fertilised they generally
receive pollen from a distinct plant and not that from
another flower on the same plant ; a cross of this latter
kind doing little or no good. I have further shown
that the benefits derived from a cross between two
plants depends altogether on their differing some-
what in constitution ; and there is much evidence that
each individual seedling possesses its own peculiar
constitution. The crossing of distinct plants of the
same species is favoured or determined in various
ways, as described in the above work, but chiefly
by the prepotent action of pollen from another
plant over that from the same flower. Now with the
Orchideae it is highly probable that such prepotency
prevails, for we know from the valuable observa-
tions of Mr. Scott and Fritz Mtiller,* that with several
Orchids pollen from their own flower is quite im-
potent, and is even in some cases poisonous to the
stigma. Besides this prepotency, the Orchideae pre-
sent various special contrivances — such as the pollinia
not assuming a proper position for striking the stigma
until some time has elapsed after their removal from
the anthers — the slow curving forwards and then back-
wards of the rostellum in Listera and Neottia — the

* A full abstract of these ob- Domestication ,' ch. xvii. 2nd edit,
servations is given in my * Yaria- vol. ii. p. 114.
tion of Animals and Plants under

290 CONCLUDING EEMAEKS. Chap. IX.

slow movement of the column from the labellum in
Spiranthes — the dioecious condition of Catasetum —
the fact of some species producing only a single
flower, &c. — all render it certain or highly probable
that the flowers are habitually fertilised with pollen
from a distinct plant.

That cross-fertilisation, to the complete exclusion of
self-fertilisation, is the rule with the Orchidese, cannot
be doubted from the facts already given in relation to
many species in all the tribes throughout the world.
I could almost as soon believe that flowers in general
were not adapted for the production of seeds, because
there are a few plants which have never been known to
yield seed, as that the flowers of the Orchidese are not
as a general rule adapted so as to ensure cross-fertilisa-
tion. Nevertheless, some species are regularly or often
self-fertilised; and I will now give a list of all the
cases hitherto observed by myself and others. In some
of these the flowers appear often to be fertilised by
insects, but they are capable of fertilising themselves
without aid, though in a more or less incomplete
manner ; so that they do not remain utterly barren if
insects fail to visit them. Under this head may be
included three British species, namely, Cephalanthera
grandijlora, Neottia nidus-avis, and perhaps Listera
ovata. In South Africa Disa maerantha often fertilises
itself ; but Mr. Weale believes that it is likewise cross-
fertilised by moths. Three species belonging to the
Epidendreae rarely open their flowers in the West
Indies ; nevertheless these flowers fertilise themselves,
but it is doubtful whether they are fully fertilised,
for a large proportion of the seeds spontaneously pro-
duced by some members of this tribe in a hothouse
were destitute of an embryo. Some species of Dendro-
bium, judging from their structure and from their

Chap. IX. CONCLUDING KEMAItKS. 29 1

occasionally producing capsules under cultivation,
likewise come under this head.

Of species which regularly fertilise themselves with-
out any aid and yield full-sized capsules, hardly any
case is more striking than that of Ophrys apifera, which
was advanced by me in the first edition of this work.
To this case may now be added two other European
plants, Orchis or Neotinea intacta and Epipadis viridi-
Hora. Two North American species, Gymnadenia
tridentata and Platantliera hyperborea appear to be in
the same predicament, but whether when self-fertilised
they yield a full complement of capsules containing
good seeds has not been ascertained. A curious
Epidendrum in South Brazil which bears two additional
anthers fertilises itself freely by their aid ; and Dendro-
bium cretaceum has been known to produce perfect self-
fertilised seeds in a hothouse in England. Lastly,
Spiranthes australis and two species of Thelymitra,
inhabitants of Australia, come under this same head.
No doubt other cases will hereafter be added to this
short list of about ten species which it appears can
fertilise themselves fully, and of about the same
number of species which fertilise themselves imper-
fectly when insects are excluded.

It deserves especial attention that the flowers of all
the above-named self-fertile species still retain various
structures which it is impossible to doubt are adapted
for insuring cross-fertilisation, though they are now
rarely or never brought into play. We may therefore
conclude that all these plants are descended from
species or varieties which were formerly fertilised by
insect-aid. Moreover, several of the genera to which
these self-fertile species belong, include other species,
which are incapable of self-fertilisation. Thelymitra
offers indeed the only instance known to me of two

292 CONCLUDING REMARKS. Chap. IX.

species within the same genus which regularly ferti-
lise themselves. Considering such cases as those of
Ophrys, Disa, and Epidendrum, in which one species
alone in the genus is capable of complete self-ferti-
lisation, whilst the other species are rarely fertilised
in any manner owing to the rarity of the visits of
the proper insects; — bearing also in mind the large
number of species in many parts of the world which
from this same cause are seldom impregnated, we are
led to believe that the above-named self-fertile plants
formerly depended on the visits of insects for their
fertilisation, and that from such visits failing they did
not yield a sufficiency of seed and were verging towards
extinction. Under these circumstances it is probable
that they were gradually modified, so as to become
more or less completely self-fertile; for it would
manifestly be more advantageous to a plant to pro-
duce self-fertilised seeds rather than none at all or
extremely few seeds. Whether any species which is
now never cross-fertilised will be able to resist the
evil effects of long-continued self-fertilisation, so as to
survive for as long an average period as the other
species of the same genera which are habitually cross-
fertilised, cannot of course be told. But Ophrys apifera
is still a highly vigorous plant, and Gymnadenia triden-
tata and Platanihera hyperborea are said by Asa Gray
to be common plants in North America. It is indeed
possible that these self-fertile species may revert in
the course of time to what was undoubtedly their
pristine condition, and in this case their various adap-
tations for cross-fertilisation would be again brought
into action. We may believe that such reversion is
possible, when we hear from Mr. Moggridge that
Ophrys scolopax fertilises itself freely in one district
of Southern France without the aid of insects, and

Chap. IX. CONCLUDING EEMARKS. 293

is completely sterile without such aid in another
district.

Finally, if we consider how precious a substance
pollen is, and what care has been bestowed on
its elaboration and on the accessory parts in the
Orchideae, — considering how large an amount is
necessary for the impregnation of the almost innumer-
able seeds produced by these plants, — considering that
the anther stands close behind or above the stigma,
self-fertilisation would have been an incomparably
safer and easier process than the transportal of pollen
from flower to flower. Unless we bear in mind the
good effects which have been proved to follow in most
cases from cross-fertilisation, it is an astonishing fact
that the flowers of the Orchideae should not have been
regularly self-fertilised. It apparently demonstrates
that there must be something injurious in this latter
process, of which fact I have elsewhere given direct
proof. It is hardly an exaggeration to say that Nature
tells us, in the most emphatic manner, that she abhors
perpetual self-fertilisation.

INDEX

BRCWX.

Aewas anthropophora, 26; pollen-
tubes, 258

■ longibracteata, 26

, monstrous flowers, 255

Acianihus exsertus. 90

fornicatus, 90, 280

Sinclair ii, 90; fertilised by

insects, 280

Acontia lucluosa with pollen-masses,
31

Acropera, pollinia of, 154, 156 ;
upper petals, 276

loddigesii, 166

luteola, 166; vessels of, 239

Adaptations, how far special, 267;
diversity of, 282

Aerides, movement of pollinia, 156 ;
secretion of nectar, 265

comutum, 265

odorata, 158

virens, 156

Amiei, on number of pollen-grains
in Orchis morio, 278

Anderson, Mr., on Dendrobium,l42 ;
on the Epidendrea, 147

Angrxcum, viscid matter in, 251

distichum, 154

ebumeum, 155

■ sesquipedale, 154, 162, 282;

nectary of, 265

Antennae of the rostellum of Cata-
setum, 184, 187

Anthers, rudimentary, 240

Apostasia, 248

Arethusex, 80

Auricles, or papillae, rudimentary,
241, 242

Babington, Prof., on the rostellum,

255
Baillon, M., on Catasetum, 191
Barkeria, 146.

Bateman, Mr., obligations to, 105,
162 ; on Cycnoches, 224.

Battersby, Dr., obligations to, 106

Bauer, Mr., on pollen-grains in
Cephalantliera, 80, 82 ; on pollen-
masses of Bletia, 143

Bee Ophrys, 52

Beer, J. G., on Catasetum, 197 ; on
Cycnoches, 224

Bees with attached pollinia, 30

Belt, Mr., on Angrxcum sesquipe-
dale. 165

Bentham on monstrous flowers of
Orchis pyramidalis, 38

Bird's-nest Orchis, 125

Bolbophyllum, 274 ; upper petals,
276

barbigerum, 138

cocoinum, 137

cupreum, 137 ; nectary of,

265

rhizophorx, 137

Bonatea speciosa, 71, 76 ; vessels of,
241; modified structure, 264;
caudiclb, 361

Bond, Mr. F., on moths with at-
tached pollinia, 30; obligations
to, 72, 75

Bracteae, secreting nectar, 266

Brassia, movement of pollinia, 156

Bree, Mr., on seed of Epipactis
latifolia', 278

Brongniart, M., on secretion of
nectar, 41; on Catasetum, 196;
spiral vessels in Orchids, 235 ; on
Uropedium, 240

Bronn, Prof., on Stanhopea devo-
niensis, 171 ; classification of or-
ganic beings, 264

Brown, C., on Sobral a macrantha^l

, Robert, on the fertilisation of

Orchids, 3; viscidity of stigma,
13 ; Ophrys apifera, 54 ; utriculi
of the stigma, 202 ; homologies of
Orchids, 234, 235, 237 ; rostellum
of Orchids, 247 ; Apostasia, 248 ;

BUTTERFLIES.

INDEX.

DEXDKOBIUM.

295

pollen-tubes, 258 ; Sprengel's

work, 275
Butterflies with attached polliuia,

31
Butterfly orchis, 69
, lesser, 73

Caladenia dimorpha, 89

Cal^ena. 89

Calanthe dominii, 161

masuca, structure of flower,

161 ; long nectary, 267, 269

veratrifolia, 280

vestita, 162

Carpenter, Dr., on Myanthus and
Catasetum, 196

Catasetidx, 178

Catasetum, peculiar rostellum, 256 ;
labellum, 270

callosum, 192, 195

luridum, 191

mentosum, 206

planiceps, 193

saccatum, structure of flower,

180-185; vessels of, 239

tabulare, 192

tridentatum, structure of

flower, 191 ; three forms on the
same plant, 196; a mule orchid,
197; vessels of, 239; peculiar
form of rostellum, 256; nectar-
receptacle, 269

Cattleya, structure of flower, 143-
148; vessels of, 239; nectary,
2U5

crispa, 147

Caudicles of polliuia in the Yandex,
152 ; development of, 252 ; struc-
ture, 260, 261

Cephalanthera, number of seeds, 277

ensi/olia, 86

grand iflora, structure of flower,

80-86 ; vessels, 239, 242 ; change
of colour in viscid secretion, 249 ;
pollen, 259 ; labellum, 269 ; num-
ber of seed, 277 ; upright position
of flower, 287 ; partially self-fer-
tile, 290

Cheeseman, Mr., on Pterostylis
trullifolia, 8S ; Acianthus sin-
clairii, 90 ; imperfect fertilisation
of Pterostylis, 280

Chysis, 146

Cirrhxa, contracted stigma, 171

Clinandrum, the, 241

Ccelogyne cristata, 146

Coryanthes, 90, 173 ; nectary, 232 ;
secretion of nectar, 265

fieldingii, 175

macrantha, 175

speciosa, structure of flower,

174

triloba, partially self-sterile, 281

Criiger, Dr , on the Epidendrex,
147; Gongora maculuta, 168;
Stanhopea, 171; Coryanthes, 173;
C. macrantha, 175 ; Catasetum,
197, 200 ; female pollen-masses,
202 ; Selenipedium palmifolium,
232 ; homologies in Orchids, 235 ;
bees gnawing the labellum, 270

Cycnoches egertonianum, 224

ventricosum, structure of flower,

220-224

Cymbidium giganteum, 155 : pol-
liuia, 252, 260; modification of
form, 263

Cypripedium, structure of flower,
226 ; secretion from, 229 ; pollen,
262 ; labellum, 275

acaule, 229

barbatum, vessels of, 239

calceolus, 229-231 ; fertilised

only by small bees, 282

candidum, 235

pubescens, 229, 230

purpuratum, vessels of, 239

Cyrtostylis, 90

Darwin, Francis, on the movement
of the awn of Stipa, 273

, George, insects fertilising Her~

minium monorchis, 61 ; Gymna-
denia conopsea, 67

, William, on Epipactispalustris,

99,100

Delpino on insects being deceived by
the presence of a nectary not con-
taining nectar, 41 ; sterility of
Spider Ophrys, 50, 51 ; Cephalan-
thera ensi/olia, 86 ; movements of
pollinia, 155 ; fertilisation of Cypri-
pedium calceolus, 231 ; imperfect
fertilisation of Ophrys arani/era
in Liguria, 280

Dendrobium, length of anther, 287

bigibbum, 142

cretaceum, 142, 291

296

DENDROBIUM.

INDEX.

HABENARIA.

Dendrobium chrysanthum, structure
of, 138-142; nectary, 265

formosum., 142

speciosum, partially sterile, 281

■ tortile, 142

Descent, lines of, 262-265

Dickie, Prof., obligations to, 124

Disa, secretion of nectar, 265

comuta, 78

grandiflora, 77 ; partially self-
sterile, 281

macro ntha, 78 ; partially self-
fertile, 290

DLsc, viscidity of, in the Ophrex,
43 ; in Catasetum, 190 ; double in
the Ophrex, 254 ; of Gymnadenia
conopsea, 272

Disperis, secretion of nectar, 265

Duchartre, M., on Catasetum and
Myanthus, 196

Dyer, Mr. Thiselton, obligations to,
175

Ejiidendrex, 142; few seed capsules
produced, 281

Epidendrum cochleatum, viscid se-
cretion of, 249

floribundum, 146; viscid se-
cretion, 249

glaucum, 146

Epipactis, vessels of, 239 ; viscid
matter, 251

latifolia, 100, 101; pollen, 259 ;

fertilised only ,by wasps, 282;
use of knob of anther, 287

microphylla, 102

palustns, structure of flower,

93-100 ; labellum, 275

purpurata, 1 02

rubiginosa, 102

viridiflora, 102 ; self-fertile,

291

Epipogium gmelini, 103

Eulophia viridis, 156 ; nectary of,
269

Evelyna, nectary of, 265

carivata, 146 ; vessels of, 239 ;

clinandrum, 241

Farrer, T. H., obligations to, 46 ;

on Bee Ophrys, 55 ; Peristylis

viridis, 63
Fertilisation, summary on, 290
fertility of English Orchids 33

Fitzgerald, K. D., on Pterostylia
longi/olia, 89 ; Calodenia dimor-
pha, 89 ; Acianthus fornicatus,
and exsertus, 90 ; Vanilla aroma-
tica, 91 ; Spiranthes australis, 115;
Thelymitra cornea and longi/olia,
127 ; numbers of Orchideae col-
lected near Sydney, 279 ; self-
fertilisation of Thelymitra carnea,
280 ; Dendrobium speciosum, 281

Flowers, use of external envelopes,
274

Fly Ophrys, 46

Frog Orchis, structure of flower, 02 ;
secretion of nectar, 63

Galeandra fwrikii, 155

Gartner on viscid matter of stigma,

249; pollen-grains in Orchids,

288
Gerard, M. M., pollinia adhering to

longicorn beetle, 16
Glossodia, 237
Gongora, labellum of, 276

atro-purpurea, 169

maculata, 168

truncota, 169

Goodyera, vessels of, 239 ; caudicle

in a nascent condition, 260

discolor, 105

pubescens, 105

repens, 103, 105

Gordon, Rev. G., obligations to, 103
Gosse, Mr., on self-fertilised seeds of

Epidendreoe, 147, 148
Gradation of organs, 247
Gray, Prof. Asa, on Gymnadenia

tridentata, 68 ; Platanthera, 75 ;

Goodyera repens, 105 ; Spiranthes

gracilis arid cernua, 111 ; Cypri-

pedium, 229, 230, 235
Gymnadenia, viscid matter, 251

albida, 43, 68

conopsea, transplanted, 32 ; se-
cretion of nectar, 4 0, 43 ; structure

of flower, 65 ; vessels, 238, 239 ;

rostellum, 255; movements of

pollinia, 271 ; disc, 272

odoratissima, 68

tridentata, 68 ; self-fertile, 291

Habenaria bifolia, 78; secretion of
nectar, 40, 43; viscid mutter, 251

HABENARIA.

INDEX

MORE.

297

Habenaria chlorantha, 43, 69 ; vessels
of, 239, 244 ; viscidity of exterior
surface, 251

Hance, Dr., on Catasetum, 197

Herbert, Dean, on Catasetum luri-
dum and Myanthus, 196

Herminium monorchis, 59 ; fertilised
by insects, 61 ; rostellum, 255

Hildebrand, F., on the ovules in
Orchids, 172

Homologies of Orchids, 232

Hooker, Dr., on Lister a, 3, 115 ;
labellum of Calxna, 89; obliga-
tions to, 115, 128, 244; spiral
vessels in Orchids, 235; varia-
bility of the labellum of Orchids,
238 ; on the rostellum, 254

Horwood, Mr., assistance from, 129

Insects, frequency of visits to Or-
chids, 33; attracted by bright
colours, 275

Irmisch on Epipogium, 103; Neottia
nidus-avis,' 125 ; flower-bud of Cy-
pripedium, 240

Krunitz, secretion of nectar by
Orchis, 36

Kurr, on Orchids secreting nectar,
38; secretion from hairs in Cy-
pripedium calceolus, 229; nectar
secreted from bracteae, 266

Labellum easily vibratile, 138 ; cup
of, not secreting nectar in the
Vandex, 269; excrescences on,
269 ; gnawed by insects, 270; its
importance to the flower, 275 ; of
Sarcanthus, 276

Ladies' slipper, 227

tresses, 1 06

Lxlia, 146

cinnabarina, 148

Lepidoptera with attached pollinia,
30,31

Leptotes, 14b

Lindley, Dr., obligations to, 129;
arrangement of Orchids, 128 ; on
forms of Catasetum, 197 ; of Cyc-
noche8, 224; homologies of Orchids,
235; on the number of genera
and species, 279

Link on homologies of Orchids, 235,
238

14

Liparis pendula, vessels of, 239;

clinandrum, 241
Listera, viscid matter, 251 ; crest

of rostellum, 287

cor data, 124

ovata, structure of, 115-124 ;

labellum, 276
Ly caste skinncrii, 155; pollen of

260

Malaxex, 128

Malaxis, viscid matter, 251 ; upper
petals, 276

paludosa, transplanted, 32 ;

structure of flower, 129-135;
vessels, 239, 241; clinandrum,
241 ; pollen-tubes, 258 ; position
of labellum affected by ovarium,
284

Maiden, Rev. B. S., obligations to,
35,64

Male flowers of Catasetum, 198

Marantacex, 238

Marshall, Mr., on sterility of trans-
planted Orchids, 32; Habenaria
chlorantha, 72

Masdevallia, clinandrum of, 241 ;
sepals, 274 ; upper petals, 276

fenestrata, 135, 136, 142

Maxillaria, movements of pollinia,
156; number of pollen-grains in
anther, 27S

ornithorhyncha, movement of

pollinia, 157, 159

Megaclinium falcatum, labellum of
138

Meniere M., on insects visiting Or-
chids, 30 ; secretion of nectar by
Coryanthes, 173 ; movement of
Catasetum, 187, 191 ; the nectar-
receptacle, 269

Mirrostylus rhedii, 132, 135

Miltonia clowesii, pollinia of, 154,
155

Modifications in Oichids, 246

Moggridge, J. Traherne, on Ophrys
scolopax, 52, 292 ; Ophrys apt/era,
56, 58, 59 ; flowering of the
Ophrex, 59

Monachanthus viridis, 196, 197, 198,
201

More, Mr. A. G., on fertility of Bee
Ophrys, 55 ; Epipactis palustris,
39, 97, 99 ; obligations to, 106

298

MOKMODES.

INDEX.

ORGANS.

Mormodes ignea, structure of flower,
208-219; viscid secretion, 249;
use of labellum, 276, 283

luxata, 219

Morren, on Vanilla aromntt'ca, 91

Moths with attached pollinia, 21,
30, 31 ; intellect of, 37

Movements of pollinia, 271

Miiller, Fritz, on Epidendrex, 148;
polliuium of Ornithocephalus, 159,
160; Sphinx moth, 163; con-
tracted stigma, 171, 172 ; ovules
of Epidendrex and Vandex, 173 ;
Cataselum mentosum, 206; brac-
teso of the Oncidium secreting
nectar, 266 ; labellum gnawed by
insects 271 ; number of seeds in
capsule of Maxillaria, 278 ; num-
ber of Orchidese in South Brazil,
279; the orchideous tribes failing
to be fertilised, 280 ; prepotency
of pollen, 289

, Hermann, on fertilisation of

Orchis mascula, 13 ; bees visiting
the flowers of Orchis latifolia,
16 ; Nigritella angustifolia, 27 ;
fertilisation of Orchids, 29 ; in-
sects puncturing laburnum flow-
ers, 41 ; Gymnadenia odoratis-
sima, 68 ; Habenaria bifolia
and chlorantha, 74; Epipactis
rubiginosa, microphylla, and viri-
diflora, 102 ; Neottia nidus-avis,
125 ; Cypripedium calceolus, 231 ;
secretion of nectar, 267

Musk Orchis, structure of flower,
59

Myanthus barbatus, 192, 199, 203;
quite sterile, 205

Nectar, secretion of, by British
Ophrese, 37, 39 ; in foreign Or-
chids, 229 ; from bracteae, 229

Nectary cut off to test the intel-
lect of moths, 37 ; length of, in
Angrxcum sesquipedale, 265

Neotinia intacta, 27, 291

Neottex, 93 ; vessels of, 241

Neottia nidus-avis, 125; pollen-
tubes, 258 ; partially self-fertile,
290

Nevill, Lady Dorothy, obligations
to, 129

Nicotiana, stigma of, 249

Nigritella angustifolia, 27
Notylia, contracted stigma, 171

Odontoglossum, 156

Oliver, Prof., obligations to, 129

Oncidium, pollinia, 153, 156, 158 ;
vessels of, 239 ; viscidity, 251 ;
bractese secreting nectar, 266

unguiculatum, development of

caudicles, 252

Ophrex, 6 ; vessels of, 241

Ophrys apifera, structure of flower,
52 ; fertility of, 54-58 ; pollen,
259; self- fertilisation, 279, 291

arachnites, 5 1

aranifera, 50 ; imperfect fer-
tilisation, 280

muscifera, transplanted, 32 ;

structure, 45 ; fertility, 49 ; self-
sterile, imperfectly fertilised by
insects, 280

scolopax, 52, 292

Orchidex, modifications in, 246

Orchis fusca, 15 ; imperfect fertili-
sation, 35 ; secretion of nectar, 37

hircina, 25 ; nectary, 39; move-
ment of pollinia, 273

latifolia, 15 ; imperfect fer-
tilisation, 35 ; secretion of nectur,
37 ; two distinct di-cs, 255

maculata, 15, 34 ; transplanted,

32 ; imperfect fertilisation, 35 ;
secretion of nectar, 37, 39; two
distinct discs, 255; rostellum,
255 ; number of seeds, 277, 278 ;

Orchis mascula, structure of flower,
6; movement of pollinia, 273 ;
number of pollen-grains, 278

militaris, sterility of, 36 ; se-
cretion of nectar, 37

morioy 15, 128 ; fertility of, in

cold season, 33; secretion of
nectar, 37, 39 ; number of pollen-
grains, 278

pyramidalis, structure of

flower, 16; movements of pollinia,
21, 272, 273 ; fertility in different
stations, 34; secretion of nectar,
37, 39 ; monstrous flowers, 38 ;
single disc, 254; rostellum, 256;
pollen-grains, 260, 261 ; contriv-
ances for its fertilisation, 264

ustulata, 25

Organs, gradation of, 247

ORNITHOCEPHALUS.

INDEX.

SPEENGEL.

299

Ornithocephalus, 160
Ovaria of Orchids, 284
Oxenden, Mr. G. C, obligations to,
25; on Epipactis purpurata, 102

Parfitt, Mr., on attached pollinia, 31
Parker, Mr. R., obligations to, 129
Pedicel of polliuium, 253 ; elasticity

of, 283
Percy, Dr., analysis of labellum of

Warrea, 270
Veristylus viridis, secretion of nectar,

43, 63 ; rostellum, 255
Petals, uses of, 274
Phaius, 146
— — grandifolius, 280
Phalanopsis, viscidity of stigma,

153; movement of polliuia, 159;

labellum, 276

■ amabilis, 159

■ grandiflora, 159 ; projection of

labellum, 269
riatanthera, 75

• ehlorantha, 69

dilatata, 77

flava, 76, 77

hookeriy 75

hyperborea, 76; self-fertile, 201

Pleurothallis ligulata, 135

• prolifera, 135

Pogonia ophioglossoides, 86
Pollen-masses, rudimentary in Mono-

chanthus, 201 ; gradation of, 257,

288
Pollen-tubes emitted from anther,

258
Pollinia, movements of, in Orchis

mascula, 12-15; in 0. pyrami

dalis, 21 ; of the Vandese, 154

of Catasetum, ejection of, 184

attachment to rostellum, 251

gradation, 257; movemeuts, 271
Pterostylis, nectary of, 232

longiflora, 87, 89

trullifolia, 86, 88 ; imperfect

fertilisation in New Zealand, 280

Rodgers, Mr., obligations to, 129 ;
on Myanthus and Monochanthits,
196; tecretion of nectar in Or-
chids, 265 ; in Vanilla, 266

Rodriguezia secunda, 159

suavcolens, in -vcmeut of pol-
linia, 156, 159

Rohrbncli, Dr., on Epipogium gme-
lint, 103

Rostellum, a single organ in the
Ophrese, 45 ; of the Yandex^
150; aborted, 242; gradation of,
247 ; of Apostasia, 248 ; diversity
of structure, 250 ; crest of, in
the Ophrex, 255 ; in Catasetum,
256

Rucker, Mr., obligations to, 129,
180, 192, 208

viscidity of stigma,
de, on pollen of

Saccolabium,
153, 156

Saint-Hilaire, A.
Orchids, 259

Sarcanthus, labellum of, 276

parishii, 142

teretifolius, pollinia of, 154,

156; viscidity, 268

Scheinsaftblumen, 37

Schomburgk, Sir R., on Catasetum,
196

Scott, Mr., on flowers of Acropera,
168, 172 ; of Gongora, 169 ; nec-
tar-receptacle, 269; number of
seeds in capsule of Acropera, 278 ;
prepotency of pollen, 289

Scudder, Mr., on Pogonia ophio-
glossoides, 86

Secretion of nectar, 36. 229, 265

Seeds, production and number of,
276, 277

Selenipedium palmifolium, 232

Self-fertilisation, summary on, 293

Sepals, uses of, 274

Serapias cordigera, 27

Sexes of Orchids, 196

Smith, Sir James, on position of
flowers in Malaxis, 129

, Mr. G. E., on bees visiting

the Bee Ophrys, 55

Sobralia macrantha, 91

Sophronith, 146

Spider Ophrys, 50

Spiranthes australis, 114; labellum,
275 ; self-fertile, 291

autumvalis, structure of flower,

106-114 ; vessels of, 239

cernua, 111

gracilis, 111

Sprengel, C. K., on fertilisation of
Orchis militaris, 36 ; secretion
of nectar by Orchis, 36 ; on Epi-

300

STAMENS.

INDEX.

ZYGOPETALTM,

pactis latifolia, 101 ; Listera,
115, 123 ; colours attracting in-
sects, 275; value of his work,
275

Stamens in Orchids, 242

Stanltopea, pollinia of, 155; label-
lum, 276

devoniensis, 171

oculata, 171

Stelis, use of the sepals, 271

racemiflora, 135

Sterility of English Orchids, 35

Stigma, viscidity of, in the Vandex,
152; utriculi, 197; gradation,
248; structure, 249

Stipa, movements of, 273

Structure, diversity of, 282, 285

Structure, importance of trifling
details, 286, 287

Thelymitra, self-fertile, 291

carnea, 127 ; self-fertile, 280

longijlora, 127

Thomson, R. B., on Goodyera

repens, 105
Til ley, H. A., on Vanilla aromatica,

91
Trevelyan, Sir C, on Bombus with

attached pollen-masses from Catt-

leya, 145
Treviranus on the secretion of

nectar, 41 ; on Bee Ophrys, 56
rrimen, R., obligations to, 40 ; on

Bonatea speciosa, 76, 77 ; Disa

grandijlora, 77, 78

Turnbull, Mr., obligations to, 129
T way-blade, 115

TJropedium, 240

Utriculi of stigma, 197, 218

Yandex, 156

, structure of, 149; pollinia,

253, 258
Vanilla aromatica, 90
Vanillidex, 90 ; few seed capsules

produced, 281
Veitch, Mr. J., obligations to, 129,

180, 220
Vessels, spiral, of Orchids, 235
Viscidity of disc in British Ophrea),

35 ; in Catasetum, 190
of rostellum and stigma, 248,

249

Waeteher on fertilisation of the

Orchids, 2
Walker, Mr. F., obligations to, 100
Wallis, Mr., obligations to, 129
Warrea, 155 ; analvsis of labellum,

270
Weale, J. Mansell, on Habenaria,

76 ; Bonatea, 11 ; Disa and Dis-

peris, 78 ; Disa macrantha, 290
Weddell, Dr., on hybrids of Aceras,

26
Wright, Mr. C, on the movement

of pollinia, 156

Zygopetalum mackai, 155

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