( 69Ó ) 



the conditions in the mother country of the plant, yet we must 

 remark that the plant was in the open air for a long time before and 

 after it had bloomed during the very hot summer of 1904 and that there 

 was no question of this specimen being sickly. We venture another 

 supposition : to us it seems that this plant makes, so to say, an 

 attempt to apogamous development, but that these endeavours do not 

 succeed. For this would plead that the endosperm develops here 

 independently of an eventual formation of an embryo and that the 

 embryo is sometimes planned, but never grows to any considerable 

 size. If this be the case, in the mother country of the plant similar 

 phenomena should be observed, but at the same time normal ferti- 

 lisation and seed- formation. We ought to know the development of 

 the embryosac, in order to know why the apogamy is unsuccessful 

 here, even though the plant makes an attempt in this direction. If 

 in the embryosac mother-cell a reduction division has taken place, 

 this would be very easy to understand and it would also explain 

 the greater facility with which tiie endosperm is formed. For, after 

 fusion of the two polar nuclei the normal number of chromosomes 

 of the 2.i'-generation (not, of course, of the endosperm) would be 

 re-established again ; we have tried to determine 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 determination is of little value ; for 

 we owe to Treub ') 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 fdls 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 there is this great difference, 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 communication 

 because it leaves unsettled whether here phenomena of partiienogenesis 

 were indeed observed. It is an open question to what extent the 

 development of an endosperm without previous fusion of the polar 

 nuclei with one of the generative nuclei of the pollen tube can be 

 brought under one of tiiese conceptions. Those who will not use 

 the word fertilisation in the case of endosperm formation, like 

 Strasbdrger, will object to it; those who embrace the opposite view, 



M. Treub. L'organe femelle et I'Apogamie du Balanophora elongata Bl. Ann. 

 du Jardin botan. de Buitenzorg XV. 1898 p. 1. See also J. P. Lotsv, Balanophora 

 globosa Jungh. Ann. du Jardin bot.m. de Buitenzorg 2me Série I. 1899, p. 174. 



