ADAPTATIONS TO FERTILIZATION. 215 



SECTION IV. CERTAIN ADAPTATIONS OF THE FLOWER TO THE 

 ACT OF FERTILIZATION. 



1. IN GENERAL. 



396. The introduction into morphological botany of the con- 

 siderations now to be mentioned should have dated from the 

 year 1793, in which Christian Conrad Sprengel published his 

 curious treatise on the structure of flowers in special reference 

 to insect aid in their fertilization. For this book, which was 

 wholly neglected and overlooked for more than sixty years, con- 

 tains along with some fanciful ideas the germs of the present 

 doctrine and many excellent illustrations of it. 1 The interest in 

 the doctrine now prevalent is witnessed by a copious special 

 literature, beginning with the publication, in 1862, of Darwin's 

 book on the fertilization of Orchids by the aid of insects. 2 



be invoked whenever there is a junction of two dissimilar organs, the petals 

 and stamens of a Lythrum or a Cuphea are united with the calyx itself, 

 instead of calyx beginning at the top of a long and simple tube. And if 

 three or more of the floral whorls may be congenitally united, why not these 

 also with the remaining one ? Van Tieghem, in his Anatomie Comparee de 

 la Fleur, maintains wholly the old view, founding it upon anatomical struc- 

 ture and his ability to trace down to the base of the ovary the distinct 

 vascular bundles of the several involved organs. 



1 C. C. Sprengel, Das entdeckte Geheimniss der Natur im Bau und der 

 Befruchtung der Blumen, Berlin, 1793. Even earlier, Koelreuter ( Vorlaufige 

 Nachricht, etc., 1761-1766) recognized the necessity of insect-aid to various 

 blossoms, and described some special contrivances for the purpose. 



2 Charles Darwin, On the Various Contrivances by which British and 

 Foreign Orchids are fertilized by Insects, and on the Good Effects of Inter- 

 crossing, London, 1862. Ed. 2, 1877. This last contains a list of the papers 

 and books which bear upon the subject, published since 1862. 



Other leading works and papers on the subject are, exclusive of the 

 other volumes and papers of Darwin, more or less referred to hereafter. 



Treviranus, Ueber Dichogamie, &c., in Bot. Zeitung, xxi. 1863. 



Hugo von Mohl, Einige Beobachtungen iiber dimorphe Bliithen, Bot. 

 Zeitung, xxi. 1863. 



Delpino, Pensieri sulla Biologia Vegetale, &c., 1867. Relazione sull' 

 Apparecchio della Fecondazione nelle Asclepiadie, &c., 1867. Ulteriore 

 Osservazioni sulla Dichogamia, &c., 1868-69, 1870, and later papers. 



Axell, Om anordningarna for de Fanerogama Vaxternas Befruchtung, 

 Stockholm, 1869. 



Hildebrand, Die Geschlechter-Vertheilung bei den Pflanzen, 1867, and 

 other papers. 



Hermann Miiller, Die Befruchtung der Blumen dnrch Insekten, 1873, and 

 papers in " Nature " and elsewhere. 



" Flowers and their Unbidden Guests," an English translation of a work 

 by Professor Kerner, which describes arrangements in blossoms for exclud- 

 ing unwelcome guests, has not yet reached us. It introduces the new terms 

 Autogamy and Allogamy, defined on the following page ; the latter compre- 



