160 BOARD OF AGRICULTURE. 



too, like the orchids which have been used to decorate this 

 hall, in which the pollen is transferred only by the agency 

 of insects, in a great number of cases insuring that the 

 ovules of one blossom shall not be impregnated by the pollen 

 of that flower, but by the pollen from some other. The 

 curious mechanisms by which the transfer is effected con- 

 stitute a very interesting subject, not without its practical 

 bearings on our topic to-night ; but we have not time to en- 

 ter upon its discussion. It is merely necessary to state, in 

 general, that, when a flower is impregnated by its own pollen, 

 it is said to be self-impregnated, or self-fertilized ; when it 

 receives pollen from some other blossom of the same species, 

 it is said to be cross-fertilized ; if it is impregnated by pollen 

 from some other species, the progeny is a hybrid. We may 

 say, therefore, that cross-fertilization of well-marked varieties 

 of the same species will yield variety-hybrids. Let us keep 

 in mind the practical distinction between variety-hybrids and 

 species-hybrids. 



The earliest important work on hybrids was written by 

 Kolreuter in Germany in 1761.^ In this treatise, and in the 

 appendices printed in 1763, 1764, and 1766, he described his 

 methods and results in artificial hybridization, detailing many 

 thousand cases. In 1849- Gartner published at Stuttgart 

 an account of his observations, covering a period of twenty 

 years or more, and described ten thousand experiments in 

 hybridizing. These great works I know only at second- 

 hand; the former by references in Nageli's works, and the 

 latter chiefly through Rev. Mr. Berkeley's abstract.' Be- 

 sides these treatises, I may refer you to the important contri- 

 butions by Andrew Knight, Herbert,* Wichura,^ Lecoq,^ Nau- 

 din, and Burbidge.'^ The literature of this subject is very 

 extensive ; for it includes not only special memoirs upon the 



1 Vorlaufige Nachricht von einigen das Gesclileclit der Pflanzen betreffen- 

 den Versuclien und Beobachtungen. Leipzig, 1761. 



2 Versuclie und Beobachtungen iiber die Bastarderzeugung im Pflauzen- 

 reich. Stuttgart, 1849. 



3 Journal Royal Horticultural Society, 1850. 



* On Amaryllidacese, to which is appended a treatise on Cross-bred Vege- 

 tables. London, 1837. 



6 Die Bastardbefruchtung im Pflanzenreich. Berlin, 1865. Chiefly devoted 

 to hybrid-willows. 



6 Fecondation et Hybridation. Paris. 



7 The Propagation and Improvement of Cultivated Plants. F. W. Bur- 

 bidge. London, 1877. A convenient and very useful hand-book. 



