272 NATURAL SCIENGE. APRIL, 
from afar, by showing the presence of honey, the insects that are 
swarming about in the air in search of food. 
‘¢ Examining, in the summer of 1789, some species of Ivis, I soon 
found that Linnzeus had erred in regard both to the stigma and the 
nectary; that the honey is fully protected from rain; and, finally, 
that there is a specially coloured place, leading insects to the honey. 
But I found more than this, namely, that these flowers cannot be 
fertilised at all except by insects, and then only by insects of fairly 
large size. Although I did not, at the time, find this idea confirmed 
by experience (this occurred in the following summer, when I actually 
saw humble-bees creeping into the flower), still I was convinced of 
its truth by the general appearance. I endeavoured, therefore, to 
discover whether other flowers are also so constructed that they can 
only be fertilised by insect agency. My investigations convinced me 
more and more that many—perhaps all—flowers which contain honey 
are fertilised by insects which feed upon the honey, and that, conse- 
quently, this nourishment of the insects is, in regard to them, the 
final end, but, in regard to the flowers, is only a means, and, indeed, 
the sole means, to a definite end, viz., their fertilisation, and that the 
entire structure of such flowers can be explained, if, in their investi- 
gation, one keep always in view the following principles :— 
‘«t, These flowers are fertilised by this or that species of insect, 
or by several. 
“2, This also will occur, that the insects, as they visit the 
flowers for honey, and in consequence of this, either rest upon the 
flowers in some indefinite way, or in a definite manner either creep 
into the flowers or run round upon them, will, of necessity, be smeared 
with pollen from the anthers, either over the greater part of their 
hairy bodies, or only over a part of them, and will rub this pollen 
upon the stigma, which, for this end, is either covered with short and 
fine hairs, or with a damp, often sticky, secretion. 
‘‘In the spring of 1790 I perceived that Orchits latifolia and O. Morto 
have, in all respects, the structure of a honey flower, but do not con- 
tain honey. I thought at first that this observation, if it did not 
actually overthrow my former discoveries, would at least make them 
very doubtful. For, since these flowers have a noney guide (so have 
I termed the differently coloured spot on the corolla)—and yet this 
cannot show insects the road to the honey, as there is none?—it 
appeared to follow that the honey guides also, on those flowers which 
do contain honey, were not really for this purpose at all, and that the 
whole thing was a mere fancy. I must, therefore, confess that this 
discovery was in no way pleasant to me. But just this spurred me 
on to study these flowers more attentively, and to observe them in 
the field, and at last I discovered that these flowers are fertilised by 
2 Darwin showed that insects visiting Orchis drill holes into the tissue of the 
spur and suck the juice therein contained, so that the flower is not really an exception 
to Sprengel’s views. 
