183. CHRISTIAN KONRAD SPRENGEL. a91 
with reference to insects. The best way, perhaps, of treating the 
subject will be to let Sprengel speak for himself. His book begins as 
follows :— 
‘In the summer of 1787 I was carefully studying the flower of 
the wood crane’s bill (Gevanium sylvaticum) and I found that the lowest 
part of its petals was provided, on the inner side and the edges, with 
fine soft hairs. » Convinced that the wise Author of Nature had not 
created a single hair without a definite end, I reflected as to what 
purpose these hairs might serve, and it soon struck me that if one 
supposed that the five honey drops, which are secreted by the same 
number of glands, were designed for the nutriment of certain insects, 
one would find it, at the same time, not improbable that care should 
be taken to keep the honey from being spoiled by rain, and that to 
attain this end these hairs were created. Every honey-drop sits on its 
gland immediately under the hairs, which occur on the edges of the 
neighbouring petals. Since the flower stands upright, and is pretty 
large, raindrops must fall into it during showers. None of the drops, 
however, can reach and mix with a honey-drop, being prevented by 
the hairs, just as drops:of sweat are prevented from running down 
into the eye by the eyebrows and eyelashes. An insect, on the other 
hand, will not be in any way hindered from reaching the honey. 
After this I investigated other flowers, and found that several of 
them had something in their structure which seemed to serve the 
same end. The longer I pursued this research, the more I perceived 
that those flowers which contain honey are so arranged that, whilst 
insects can easily reach it, it canuot be injured by rain. I concluded, 
therefore, that the honey of these flowers, at least primarily, is 
secreted for the benefit of insects, and, that they may obtain it pure 
and uninjured, is protected from rain. 
“In the following summer I investigated the forget-me-not 
(Myosotis palustvis), and I found that not only does this flower contain 
honey, but that the honey is fully protected from rain. At the same 
time, however, I was struck by the yellow ring which surrounds the 
mouth of the corolla tube, and contrasts so beautifully with the azure 
blue of the limb. Is this circumstance also, thought I, to be referred 
to insects? Has Nature coloured this ring for the express purpose 
of showing insects the way to the honey receptacle? I examined, 
with regard to this hypothesis, other flowers, and found that the 
majority supported it. For I saw that those flowers whose corolla, 
as commonly happens, is coloured differently in one place than in the 
rest, always have these spots, figures, lines, or dots of special colour 
at the place where the entrance to the honey is found. Now I 
reasoned from the part to the whole. If, I thought, the corolla is - 
coloured in special places on account of insects, its general colour 
must also be on their account; and if the special local colouring 
serves to direct to the honey an insect which has already alighted 
upon the flower, the general colour of the corolla must serve to attract 
