1893. CHRISTIAN KONRAD SPRENGEL. 273 
certain flies which, deceived by the appearance, imagine the spur to 
contain honey, and creeping in, tear the pollen masses from their 
chambers and bring them upon the sticky stigma. Flowers of this 
type, which have fully the appearance of honey flowers, but do not 
contain honey, I call ‘sham honey-flowers’ (Scheinsaftblumen). 
That there are more of them, I saw in the same year on the common 
birthwort (Aristolochia Clematitis). I found, namely, that this flower 
also, which contains no honey, is formed in every way like a honey 
flower, and, on this account, small flies of all kinds creep into it. In 
the following summer I saw clearly that this flower is a true wonder 
of nature, namely, that these flies are led by the appearance of the 
flower to creep into it, that they may fertilise it, and that they are 
held prisoners in it until they have done so, but that as soon as this 
has occurred they are released from detention. 
‘“‘In the summer of the year above mentioned I discovered, in 
Epilobium angustifolium, something upon which I had never happened 
before, namely, that this hermaphrodite flower is fertilised by humble 
and hive bees, not, however, each flower by its own pollen, but the 
older flowers by means of pollen carried by insects from the younger.3 
This observation shed great light upon many of my earlier discoveries. 
I was especially pleased when I found a similar method of fertilisa- 
tion in the wild love-in-a-mist (Nigella arvensis). In the summer of 
1788 I had perceived the beautiful arrangements of the nectaries 
of this flower. In the following summer observation showed me that 
it was fertilised by bees. At the time I thought I fully understood 
how this came about. Now, however, I found that I had erred in 
regard to the last point, because then I still believed all hermaphro- 
dite flowers to be fertilised by their own pollen. 
‘Finally, last summer I studied the common spurge (Euphorbia 
Cypavissias) and found in it an arrangement the exact opposite of that 
described above, the flower being fertilised by insects, but in sucha 
way that they carry the pollen of older flowers to the stigmas of 
younger ones. 
‘Upon these six chief discoveries, made in five-years, is founded 
my ‘ Theory of Flowers.’ ” 
After a discussion of the subject of nectar and its uses, in which 
he demolishes the older views, such as that the nectar causes the 
growth of the ovule to a seed by keeping it damp, or that it is an 
injurious substance, whose removal by insects is therefore a direct 
benefit to the plant, Sprengel goes on to point out how in all honey 
flowers the following five points may be observed, viz.:—(1) The 
honey gland or nectavy; (2) the honey receptacle, in which is stored the 
honey secreted by the gland; (3) some arrangement to protect the 
® The flower is dichogamous, i.e., the stamens and pistil do not ripen simul- 
taneously. In young flowers the stamens are ripe, the style folded back out of the 
way; in older ones the style occupies, with its ripe stigmas, the place formerly 
held by the now empty and withered stamens. This phenomenon is termed pro- 
tandrous dichogamy or protandry ; the reverse case (Euphorbia) protogyny. 
Ti 
