"DOUBLE FERTILISATION" IN PLANTS 423 



nucleus causally related to the degenerate production of a mere 

 food tissue? It has been suggested by Miss Sargant 1 that it is, 

 and that we have in the endosperm an embryo withheld from its 

 true development by the mass of vegetative nuclear matter in its 

 composition. If this view be accepted, then we may suppose the 

 Angiosperms to be derived from forms which habitually pro- 

 duced two embryos in each embryo sac. In this connection it 

 must be remembered that the embryo in Gymnosperms survives 

 at the expense of several of its brethren. 



On the other hand, there have been those who look upon the 

 endosperm derived from the triple fusion as part of the vegeta- 

 tive contents of the spore, the production of which has been 

 delayed until after the formation and fertilisation of the female 

 organ. This would be as though a fern spore should form 

 archegonia at the beginning of germination, and after these 

 had been fertilised, produce the main bulk of the vegetative pro- 

 thallus for the support of the young embryo. Prof. Strasburger, 2 

 who is the chief exponent of this view, looks upon the fusion 

 of the male and female nuclei to form the supposed belated 

 prothallial tissue, as purely secondary, and more or less accidental. 



It will be remembered that one of the tests of fertilisation is 

 the carrying on of paternal qualities, and that this is effected by 

 " double fertilisation " has been brought out very strikingly by 

 hybrid experiments. 



The very remarkable transmission of endosperm characters 

 belonging to the paternal side of crossed races of maize had 

 long been a puzzle to plant breeders. Very obvious and unmis- 

 takable differences exist in the endosperms of the varieties of 

 maize. While starch is the form of food storage in many, in 

 some it appears as sugar. Another constant and differentiating 

 feature is found in the colour of the endosperm which, showing 

 through the thin covering layers, colours the whole seed. 

 When two such widely differing races are crossed, the colour 

 and chemical nature of the endosperm of the variety from which 

 the pollen was obtained may appear in the ripening seed of the 

 female plant, 3 and this was always quoted as an extreme instance 



1 " Recent Work on the Results of Fertilisation in Angiosperms." Annals of 

 Botany, vol. xiv., Dec. 1900. 



2 "Einige Bemerkungen zur Frage nach der ' doppelten Befruchtung' bei 

 den Angiospermen." Bot. Zeit. ii. 1900. 



1 H. de Vries, " Sur la fecondation hybride de l'albumen." Comptes rendics de 

 PAcad. d. Sci., Paris, 1899. 



