i893. CHRISTIAN KONRAD SPRENGEL. 271 



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 {Geranium sylvaticnm) 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 cannot 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 palustris), 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 



