22 



cance of consjncuous llowt-rs. His took, 

 now a botanical classic, attracleil but little 

 attention; his jjublisher did not even send 

 him a copy of it, and in discouragement he 

 did not publish the second volume, but 

 turned from the study of i)lants to that of 

 languages. The title of the work, "The 

 Secret of Nature in the Form and Fertiliza- 

 tion of Flowers Discovered," affords us the 

 pleasure of knowing that he rightly esti- 

 mated the imjjortance of his observations. 

 Sprengel clearly states, as is now well es- 

 tablisheil, that the biight hues of flowers 

 serve as signals to attract the attention of 

 nectar-loving insects Hying near by. He 

 was led to this conclusion very fitly by the 

 study of MtjoHoiis, or the forget-me-not. 

 He has not been forgotten. His name and 

 theory were rescued from obscurity by Dar- 

 win; his book a few years ago was repub- 

 lished at Leipsic, and is now universally 

 recognized, says Mueller, as having "struck 

 out a new path in botanical science." 



Sprengel was convinced that the wise 

 Framer of nature had not produced a single 

 hair without a definite purpose, and he ex- 

 amined a great many liowers for the pur- 

 pose of learning the meaning of their forms 

 and the arrangement of their parts. The 

 salver-formed tlower of the forget-me-not is 

 sky-blue with a yellow eye. "While study- 

 ing the llower of myosotis I w'asstruck," he 

 says, "by the yellow ring which surrounds 

 the opening of the corolla tube, and which 

 is beautifully conspicuous against the sky- 

 blue color of the limb. Might not, I 

 thought, this circumstance also have some 

 reference to insects? Might not Nature 

 have specially colored this ring, to the end 

 that it might show insects the way to the 

 n<'ctar-reservoir? "On further observation 

 he found that the entrances to many other 

 flowers were marked with spots, lines, and 

 dots dilTerently colored from the rest of the 

 corolla. These markings he called " nectar- 

 guides." "If the particular color of one 

 part of a flower," he rightly inferred, 

 "serves to enable an insect which has set- 

 tled on the tlower easily to find the right 

 way to the nectar, then the general color of 

 the corolla is serviceable in rendering the 

 flowers provided with it conspicuous even 

 from afar to the eyes of insects that hover 

 anumd in the air in search of food." 



Sprengel decided that flowers secrete nec- 

 tar for the sake of attracting insects, and 

 that it is protected by hairs or nectaries in 

 order that they may enjoy it pure and un- 

 si. oiled. At first he thought that the 

 flowers receive no service in return; but he 

 soon observed that the guests pollinated the 

 liowers. He even noticed the frequent 

 orcurrence of cross-pollination, and remarks 

 that "it seems that Nature is unwilling 

 iliat any flower should be fertilized by its 

 own pollen." He described the manner in 

 \K Inch some 500 flowers were pollinated; but 

 as he knew little about insects he did not 

 pay much attention to the different kinds 

 of visitors. 



liut while Sprengel had learned the secret 



Gleanings in Bee Culture 



of flowers, and knew that their colors, odors, 

 and forms were not useless characters, he 

 failed to discover why cross-pollination is 

 beneficial; and this omission, as Mueller 

 has remarked, was for several generations 

 fatal to his work. In 1841, Robert Brown, 

 an eccentric English botanist of great learn- 

 ing, advised Darwin to read Sprengel's 

 book. " It may be doubted," says Francis 

 Darwin, "whether Robert Brown ever 

 planted a more beautiful seed than putting 

 such a book into such hands." Thus is the 

 torch of learning, shining with ever increas- 

 ing effulgence, handed on from one investi- 

 gator to another. Darwin was already en- 

 gaged in studying British orchids, of which 

 he wrote to Bentham, "They are wonder- 

 ful creatures, these orchids." His interest 

 in the structure and iwllination of these 

 curious plants was greatly increased by 

 reading what the old German pastor had 

 done. Darwin soon discovered that frequent 

 crosses increase both the vigor and produc- 

 tiveness of the stock, and that an occasion- 

 al cross is indispensable. The principal 

 agents which nature employs for this pur- 

 pose are insects, birds, wand, and water. So 

 impressed was Darw^in with the importance 

 of cross-fertilization that he closed his fa- 

 mous book on orchids, which marks the next 

 great epoch in flower ecology, with the 

 words, "Nature abhors perpetual self-fer- 

 tilization." "The charm," says Mueller, 

 "was now broken, and the value of 

 Sprengel's work was at once recognized." 

 "The merits of poor old Sprengel," says 

 Darwin in his biography, "so long over- 

 looked, are now fully recognized many 

 years after his death." 



In 18<jG, Darwin's Origin of Species and 

 book on orchids was read by Hermann Muel- 

 ler, a young teacher at Lippstadt, Germany, 

 who thenceforth enthusiastically devoted 

 the rest of his life to the study of the polli- 

 nation of flowers. Many other investiga- 

 tors were also stimulated by these epoch- 

 making books to study the charming prob- 

 lems of floral structure, as Delpino in Italy, 

 Axel in Sweden, Hildebrand in Germany, 

 Asa Gray in North America, and Fritz 

 Mueller in South America. But they were 

 all easily surpassed by Hermann Mueller, 

 who is still regarded as the foremost of floro- 

 ecologists. In Thuringia and in the Alps 

 he examined many hundreds of blossoms 

 and observed the visits of insects by thou- 

 sands. He was the first to collect and pub- 

 lish lists of flower-pollinators on an exten- 

 sive scale, and the biology of flowers may 

 thus be said in its broadest sense to have 

 been established by him. Never since has 

 this branch of botany been cultivated wiih 

 equal success. His book, "The Fertiliza- 

 tion of Flowers," ranks with the works of 

 Sprengel and Darwin, and marks the third 

 great epoch in the history of the ecology of 

 flowers. It is illustrated by many excellent 

 wood-cuts, the drawings for which were 

 made by Mueller himself. It contains de- 

 scriptions of the floral mechanisms of a great 

 number of species of plants, with lists of 



