646 
THE GARDENING WORLD 
June 12, 1886. 
the flowers, not only satisfies temporal wants, but 
ensures the perpetuation of the Orchids, and future 
supplies of food to the progeny of insects. This food 
is of various kinds, the most obvious of which is nectar, 
generally produced at the base of the labellum, or in a 
spur forming part of that organ. It is also produced 
by the sepals as in Disa and others, in all of which 
cases it may be free; but in other cases, insects have 
to pierce the inner lining of the nectary to obtain it. 
The fleshy protuberances on the labellum of many 
Orchids are eaten by insects, and doubtless serve also 
as obstructions on elevated platforms, causing visitors 
to brush against the rostellum. The idea of insects 
piercing or eating fleshy parts has been much dis¬ 
credited, but actual observation of the action sets the 
matter at rest, and a paper read before the Royal 
Microscopical Society, in April, 1874, describes the 
hardened and pointed proboscis of a moth from West 
Africa adapted for piercing and abstracting the juices 
of plants. The pollen is too precious, and nature too 
rigidly economical in this instance to favour the 
development by natural selection of pollen eating 
insects, seeing that not merely part of the pollen would 
be lost in this manner, but the beautiful mechanism to 
ensure the transportal of the rest would generally be 
destroyed. Insects also meet with serious difficulties 
n obtaining a livelihood, and must frequently be 
encumbered by pollinia, or the adhesive glands fixed 
to their proboscides, eyes, and other parts of the head. 
The pollinia of Gatasetum are shot with considerable 
violence at visitors. In our hothouses, ants get glued 
to the stigmatic disk and die there. 
Colour and Odour. 
Colour is one if not the leading attraction that serves 
to allure insects from a distance, and in cases of high 
specialisation must lend material assistance in finding 
or recognising the species from which they expect to 
obtain food. In no other order, probably, do we find 
such a variety of colour, ranging from the primitive green 
through yellow, white, pink, red, scarlet, purple, and 
ultimately blue, as in Yanda cserulea (cseruleseens), 
Calanthe natalensis and others. These by no means ex¬ 
haust the number of shades and tints, while an enormous 
proportion are exquisitely variegated with several 
distinct colours—another instance of high colour de¬ 
velopment. The higher colours were developed from 
the primitive and simpler ones by natural selection. 
Insects in searching for food were attracted by those 
flowers that varied and rendered themselves more con¬ 
spicuous. This colour variation merely served to direct 
insects to the flowers, and distinguish them from the 
ordinary vegetative portion of the plant. Excretory 
products being more generally produced by the floral 
organs than other parts, these colours became associated 
with a store of rich food for insects. Excretory sub¬ 
stances outside the floral organs, being of little or no 
service to the process of fertilisation, and consequently 
reproduction would have little or no chance of preser¬ 
vation by selection. 
The odour of flowers has a direct bearing on their 
fertilization, and acts either in conjunction with or 
independently of attractive colours in drawing the 
attention of insects. Many species possess an odour, 
the exact counterfeit of that of some other plant, such 
as the Primrose, Violet, Cloves, Cinnamon, and others. 
No doubt all these are intimately associated with the 
insect or class of insects that visit the respective kinds, 
or, in other words, serve as a distinctive mark by which 
they may he recognised. Pleasing odours are mostly 
associated with more or less highly attractive colours ; 
but Odontoglossum hastilabium and Ccelogyne fuli- 
ginosa have a positively disagreeable smell, and are, 
therefore, exceptions. Odontoglossum gloriosum, 
Cattleya aurea Dowiana, Epidendrum macrochilum, 
Stanhopea grandiflora, Maxillaria venusta, and a host 
of others have conspicuous, showy and deliciously 
fragrant flowers, so that they possess a double attraction. 
Species with fragrant and pale or white flowers would 
lay themselves open to fertilisation by night-flying 
moths. On the other hand, Acropera concolor, On- 
cidium bifrons, Eria flava, and some others are typical 
of a number with moderately conspicuous flowers, and 
a somewhat disagreeable odour, especially when the 
flowers are past their best. Bulbophyllum Careyanum 
has inconspicuous and positively foetid flowers, which 
doubtless attract carrion flies, as the Sauromatums do 
in our hothouses, deceiving the flies, and causing them 
to lay their eggs there. 
Pathfinders and Adaptations. 
All parts of the flower are subservient to the process 
of fertilisation, and all adaptations that are in any way 
beneficial to the plant in this respect are developed by 
natural selection. By pathfinders is meant anything 
that serves to guide insects to the nectary, or the place 
where nectar is secreted, resulting, generally, in effecting 
cross-fertilisation. Colour is a prominent feature in 
this respect, and when the floral envelopes are parti¬ 
coloured or variegated, a concentration of colour takes 
place often on the upper half of the labellum (consti¬ 
tuting the landing-place), and from thence it extends 
towards the nectary in bands, streaks, or fine pencilled 
lines. Cattlcyas of the C. labiata group are examples 
of this, and no better instance could be given than C. 
aurea Dowiana. Numerous instances of spots, blotches, 
or lines occur amongst Dendrobiums, Odontoglossums, 
Epidendrums, and others wdiich would be too numerous 
to mention. The labellum of the highly-developed 
Vandas is either darker or altogether differently coloured 
to the sepals and petals. In Vanda cierulea it is a 
deeper blue than the sepals and petals, with three 
raised lines or ridges leading to the nectary, behind 
the orifice of which is a bright yellow spot surrounded 
with blue, and that again with white. There are seven 
distinct shades of colour in Oncidium leucochilum, five 
of which are concentrated on the labellum and column. 
The shape of the labellum itself probably serves as a 
guide in the largest number of species, speaking gene¬ 
rally, and this shape is frequently assisted by ridges 
and furrows or raised plates, as in Ccelogyne, Lisso- 
chilus, Orchis pyramidalis, several species of Lselia, 
Bletia, and others. Ridges like these are very service¬ 
able to the guidance of night-flying moths in white 
flowers. Elevated disks and other peculiar obstructions 
are placed on the labellum of Phalaenopsis, and a 
tongue-like process on that of Maxillaria, Lycaste, 
Scuticaria, Prominoea, and others. I cannot look upon 
all these as meaningless and useless processes, but as 
contrivances and adaptations for assisting or compelling 
visitors to effect fertilisation in a certain definite way. 
The floral organs, or any one or more of them, may 
become adapted to suit the convenience of a class or 
kind of insects, or of one species only. This latter case 
is one of extreme specialisation, and is significant from 
the fact that such a species is on the high road to ex¬ 
tinction. This is evident, seeing that if any species of 
Orchid is dependent on one species of insect for fertili¬ 
sation, and, consequently, reproduction by seeds, its 
welfare is linked with that insect; and should circum¬ 
stances become so unfavourable for the latter as to cause 
its extinction, the Orchid must either take to self¬ 
fertilisation or, failing that, become extinct also. The 
species of Angrrecum, judging from the length of the 
nectary, are all more or less highly specialised, requiring 
insects with a long proboscis to fertilise them. This is 
carried to an extreme in A. sesquipedale, and although 
the existence of a moth in Madagascar has not yet 
been discovered, and may never be discovered, with a 
proboscis long enough to reach the bottom of the 
nectary of 11 ins. or 12 ins., it need never disprove the 
existence now or at a former time of such a moth. The 
question arises how long the Angrsecum could maintain 
itself by purely vegetative growth without reproduction 
by seeds, provided the moth were already extinct. 
Catasetum offers another case of extreme speciali¬ 
sation, where many species are sexually differentiated, 
with a perfect stigma and perfect pollinia on distinct 
individuals. They are so different in appearance that 
the older botanists described them under different 
genera. This being so insects are indispensable for the 
transference of the pollinia from the staminate to the 
pistillate flower. The rostellum is greatly elongated, 
bifurcate, and highly sensitive, and when touched re¬ 
leases the viscid gland, when the elastic pedicel ejects 
the pollina with great force, a phenomenon which occurs 
in no other genus. Large and strong insects only are 
able to effect fertilisation, offering a remarkable instance 
of co-adaptation between the animal and vegetable king¬ 
doms. Insects have suffered the same modification as 
the Orchid ; but time forbids its discussion here. 
{To be continued). 
-->:£<>-— 
CULTURE OF THE HERBACEOUS 
CALCEOLARIA. 
As the season has come round for making arrange¬ 
ments for a supply of plants of this indispensable flower 
for next year’s use in the greenhouse and conservatory, 
a few notes on its general treatment may he timely to 
some of your readers. It may be said truly that the 
Calceolaria has no rival in its season in the brilliant 
colours and the massive splendour of abundant in¬ 
florescence it is capable of producing ; but in order to 
attain the most perfect results, it is necessary to culti¬ 
vate with great care at every stage. Every operation 
must be done at the right time, and prevention of evil 
rather than the cure of the consequences of evil should 
be the rule of management in every detail. 
Sowing the seed is the first operation requiring 
attention. This may be done any time from May to 
July, but we prefer June for our own sowings, as we 
find plants raised from the beginning to the middle of 
that month generally turn out more robust in growth 
than those sown at an earlier or later period. The 
compost for the seed-pots cannot be formed of anything 
better than light fibrous loam and leaf-mould—the 
latter not absolutely decayed, but rubbed through a 
|-in. riddle—in about equal parts, with as much sharp 
sand as will render the mass visibly sandy and porous. 
The seed being very fine and dust-like, must be sown 
with great care, so as to distribute it evenly and thinly 
over the surface of the pot or pan, the latter being 
preferable because more easily drained in a thorough 
manner, which is an important point as bearing on the 
success of the operation. 
The even distribution of the seed will be more easily 
attained if the surface of the soil is smoothed firmlv 
over by means of pressing with a hoard, or the bottom 
of a flower pot. The merest dusting of the finest 
particles of the earth will be sufficient covering, after 
applying which, lightly water with the finest rose 
watering pot, and place a square of glass over the pot, 
large enough to quite cover the rim. The pot may 
then be placed in a frame, or any position where it 
may enjoy moderate shade till germination is com¬ 
pleted, which will be in from nine to twelve days after 
sowing. During this time, if the position is a moist 
and somewhat shady one, little or no water ■will be 
required ; the square of glass will moderate evapora¬ 
tion, however^ no matter what the position may he ; 
but it should be turned daily or wiped dry, in order to 
prevent drip, which would be injurious to the seeds in 
process of germination. 
When the plants are fully brairded, remove the 
square of glass, and place the pot in a light position 
close to the glass, and where a free current of air 
without draught will reach them ; but they must, 
while being fully exposed to ordinary light, he shaded 
from the midday sun, and a little before and after that 
period of the day. During this stage of their growth, 
the plants will require a moderate amount of moisture, 
but it should not be applied overhead, else damping 
may result, which is very difficult to correct after it is 
once induced. The safest way to supply water to such 
tiny plants is to immerse the pot nearly to the level of 
the soil in a tank or tub of water for a minute or two. 
In this way the roots and the soil about them will he 
sufficiently saturated with moisture, without any wet¬ 
ting of the foliage or the surface of the soil in immediate 
contact with it—a condition of things under which 
damping can never occur. 
Pricking-off the seedlings should be promptly 
attended to, so soon as the first rough leaf is formed. 
To the inexperienced this may appear much too early, 
as at that stage the plants are very small indeed ; but 
it is dangerous to delay, as damping may set in and 
carry the whole off in a very short time. The hand¬ 
ling of the plants is impossible so early without 
mechanical aid ; a small forked stick with which to lift 
each plant separately, and a fine-pointed dibber are, 
however, the only tools requisite. The fork must ob¬ 
viously he very fine, and is easily formed out of a strip 
of lath or a wooden label. Pans, for the reason before 
stated, are preferable to pots at this stage, and the 
compost may be the same as that prescribed for the 
seed pots. The plants should be even more carefully 
shaded from direct sun light than before, and kept 
close for a few days afterwards. The tedium of prick¬ 
ing off the very smallest seedlings should not be allowed 
to deter from securing a considerable portion of them, 
even supposing there is a surplus of stock over and 
above what may be required to grow on. The weakest 
at the commencement may and do often turn out the 
most robust plants in the end, but a certain proportion of 
them invariably produce the finest colours, so that in 
throwing them away wholly the choicest varieties of 
the batch may be unwittingly sacrificed. The distance 
between the plants may be about an inch each way. 
A month or six weeks after being pricked off, the 
plants should, if all goes well, be large enough to place 
in small 60 pots, which must be well drained. The 
