"DOUBLE FERTILISATION" IN PLANTS 421 



effects fertilisation by fusion with the ovum ; but what is the fate 

 of the other? 



If a botanist had been asked this question previous to the 

 publications of Professors Nawaschin and Guignard, he would 

 have said that the second male nucleus merely withered away 

 after its successful fellow had fulfilled its destiny. But the 

 papers of '98 and '99 conclusively demonstrated, by inde- 

 pendent researches, that in Lilium Martagon the second sperm 

 also fuses with two neighbouring nuclei of the ovum, thus 

 forming a triple nuclear fusion. As the result of the fusion of 

 one male nucleus with the ovum, an embryo is produced ; as 

 the result of the fusion of the other male nucleus with two 

 nuclei, the endosperm upon which the embryo feeds is produced. 



These new results were received at first with some caution 

 by botanists, not 'surprising when we consider that the history 

 of fertilisation and the development of embryo and endosperm 

 in Lilium Martagon and many other flowering plants had been 

 described repeatedly. The previous failures to observe the 

 triple fusion were probably due partly to a slight difference in 

 time between the fertilisation of the ovum and the fusion with 

 the endosperm-producing nuclei, and partly to the frequent 

 occurrence of fusion of two of the three nuclei of the triple fusion 

 before the arrival of the third. 



The production of endosperm from the fusion of two nuclei 

 of the embryo sac had always been looked upon as an 

 interesting and rather puzzling phenomenon, for the explanation 

 of which many diverse hypotheses had been put forward. The 

 intrusion of a male nucleus into this fusion seemed to some 

 infinitely to increase the incomprehensibility of the process, and 

 many took refuge in the view that fusion with endosperm- 

 producing nuclei was largely accidental, and without meaning, 

 and might equally well take place with one of the other nuclei 

 present. 



For the next few years, therefore, the statement given above 

 as to the fate of the second male nucleus would have received a 

 qualifying addition, to the effect that in some cases it apparently 

 persisted and fused with the endosperm-producing nuclei, or 

 possibly with another sister cell of the ovum. The latter fusion, 

 though often referred to as a possibility, has, I think, never been 

 demonstrated. 



During the last few years, however, so numerous and wide- 



