SOME ASPECTS OF 

 "DOUBLE FERTILISATION" IN PLANTS 



By ETHEL N. THOMAS, B.Sc. 



University College, London 



The last few years have seen several interesting and important 

 advances in botanical science, and although some of these were 

 initiated at the close of the last century, one is yet tempted to 

 think of them as twentieth-century discoveries. The application 

 and elucidation of them certainly belongs to the present century, 

 and they may at least be looked upon as new foundation stones 

 for the erection of twentieth-century superstructures. 



Among these, though by no means the most important, is the 

 discovery of the obscure process known as " double fertilisation." 



The phenomenon known as double fertilisation — perhaps 

 rather unfortunately so called — was first described by a Russian 

 observer, Nawaschin, 1 to a Russian audience in August of 1898 

 at Kief. It was brought further into prominence the next year 

 by the publications of Prof. Guignard, 2 who also had discovered, 

 in the same plant, the process described by Nawaschin. 



Lilium Martagon had long been the classical plant for the 

 study of fertilisation ; nevertheless these workers found that it 

 amply repaid a ' Revision der Befruchtungsvorgange.' 



The processes of approximation of the male and female 

 elements, which culminate in the fusion of the male and female 

 nuclei, may be said to be initiated when, by the agency of wind 

 or insect, pollen grains are deposited upon the receptive stigma, 

 where they germinate with the production of a tube. 



When the pollen tube sets out upon its long and complicated 

 journey in search of the ovum deeply seated in the tissue of the 

 ovule, it bears within it two male nuclei, or sperms, one of which 



1 " Resultate eines Revision der Befruchtungsvorgange bei Lilium Martagon." 

 Bull, de PA cad. imp. des Sciences de St. Petersb. ix. 1899. 



2 " Sur les antherozoides et la double copulation sexuelle chez les vegetaux 

 angiospermes." Comptes rendus Acad. d. Sci., Paris, 1899. 



420 



