232 



cessful hère, even though the plant makes an attempt in 

 this direction. If in the embryosac mother-cell a réduction 

 division has taken place, this would be very easy to un- 

 derstand and it would also explain the greater facility 

 with which the endosperm is formed. For, after fusion of 

 the two polar nuclei the normal number of chromosomes 

 of the 2a;-generation (not, of course, of the endosperm) 

 would be re-established again ; we hâve tried to détermine 

 this number and it seemed to us to be 20 to 24. But as 

 long as we do not know how the endosperm is formed 

 this détermination is of little value ; for we owe to T r e u b *) 

 the knowledge of a case of endosperm formation, with 

 Balanophora elongata, where the endosperm nuclei are 

 formed by division of one of the two polar nuclei. It is, 

 to be sure, the only case on record where an embryosac 

 fills with endosperm, without a normal embryo being 

 formed. In this respect the ovules of Dasylirion, described 

 by us, could be compared with Balanophora. On the other 

 hand Ihere is this great différence, that with Balanophora 

 an embryo is later formed from part of the endosperm 

 and of this there is no question with Dasylirion. 



We put the word apogamy at the head of this com- 

 munication because it leaves unsettled whether hère phe- 

 nomena of parthenogenesis were indeed observed. It is an 

 open question to whatj extent the development of an en- 

 dosperm without previous fusion of the polar nuclei with 

 one of the generative nuclei of the pollen tube can be 

 brought under one of thèse conceptions. Those who will 

 not use the word fertilisation in the case of endosperm 

 formation, like Strasburger, will object to it; those 



1) M. Treub. L'organe l'emelle et l'Apogamie du Balanophora 

 elongata Bl. Aon. du Jardin botan. de Buitenzorg XV. 1898 p. 1. 

 See also J. P. Lots y, Balanophora globosa Jungh. Ann. du Jardin 

 botan. de Buitenzorg 2ine Série L 1899, p. 174. 



