( 689 ) 



of small grains which stained very strongly and which somehow 

 make the impression of nucleoli ; of a nucleus nothing is found any 

 longer, unless we apply the name to some thick, coloured masses. 



Three ovules, fixed on December 15, all showed the same picture. 

 A strongly developed endosperm is present with very thick cell- 

 walls, absorbing saflVanine more or less, and protoplasts which are 

 entirely foamy and in which nothing of a finer structure is found. 

 Tills endosperm must evidently be reckoned among the horny ones; 

 it was extremely di/Ticult to cut. Sections of the ovules could only 

 be made after treatment with hydrofluoric acid. It is not impossible, 

 of course, that the foamy appearance of the protoplasts must be 

 ascribed to this treatment, although we do not think this probable 

 on account of other experience with this method. In the endosperm 

 some fissures are visible, the last remnants of the cavity of the 

 embryosac 



Finally an ovule with an endosperm was found among the material 

 collected on January 19. Here also cutting was only possible after 

 treatment with hydrofluoric acid. The endosperm is entirely dis- 

 organised, borders of cells can scarcely be recognised. No more than 

 in the preceding cases we think this must be ascribed to the ratinner 

 of treatment. 



We have now described all cases of formation of an endosperm, 

 observed by us. It will have been noticed that the order is not 

 chronological, the ari;angement was such that we gradually proceeded 

 from the least developed to the complete endosperm. From this it 

 follows already that the formation of an endosperm takes place very 

 irregularly with these ovules, sets in now sooner, then later, and 

 that the endosperm may pass into disorganisation at various stages 

 of development. 



Summarising, it appears that with Dasylirion acrotrichum an endo- 

 sperm is formed without fertilisation. This endosperm finally disorga- 

 nises ; it may do so already at a pretty early stage of development, 

 but it may also first attain its complete 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 how- 

 ever very soon passes into a state of disorganisation. 



One may now ask to wliat cause this disorganisation must be 

 ascribed. It might be suspected that the circumstances of this Dasylirion 

 were abnormal. Although we grant that these were diiferent from 



