231 



the formation of an endosperm takes place very irregularly 

 with thèse ovules, now sets in sooner, then later, and that 

 the endosperm may pass into disorganisation at varions 

 stages of development. 



Summarising, it appears that with Dasylirion acrotrichum 

 an endosperm is formed without fertilisation. This endo- 

 sperm finally disorganises; it may do so [already at a 

 pretty early stage of development, but it may also first 

 attain its complète development. But an embryo could 

 never be found together with such an endosperm. From 

 this it does not follow, however, that it could never be 

 formed together with an endosperm, especially since in 

 three ovules — in which, to be sure, no endosperm was 

 formed — in the top of the embryosac a cell-body was 

 found which we take to be an embryo, which however 

 very soon passes into a state of disorganisation. 



One may now ask to what cause this disorganisation 

 must be ascribed. It might be suspected that the circum- 

 stances of this Dasylirion were abnormal. Although we 

 grant that thèse were différent from 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 spécimen being 

 sickly. We venture another supposition : to us it seems 

 that this plant makes, so to say, an attempt to apogamous 

 development, but that thèse endeavours do not succeed. 

 For this would plead that the endosperm develops hère 

 independently of an eventual formation of an embryo and 

 that the embryo is sometimes planned, but never grows 

 to any considérable size. If this be the case, in the mother 

 country of the plant similar phenomena should be obser- 

 ved, but at the same time normal fertilisation and seed- 

 formation. We ought to know the development of the 

 embryosac, in order to know why the apogamy is unsuc- 



