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gatioi) could he got. Nothwithstanding this the preserved material was 

 examined, since it was possible that only the unfavourable conditions 

 under which Dasylirion lived in the Botanical Garden at Utrecht, 

 were the reason why no ripe seed was formed. 



On microscopical examination phenomena were indeed observed 

 which seemed to point to apogamy or parthenogenesis, but the mate- 

 rial proved insufficient to obtain a consistent result. Leaving apart 

 even the already mentioned fact that not a single ripe seed was 

 produced, the number of ovules in which ultimately anything parti- 

 cidar could be observed, was extremely small. For microscopic 

 examination revealed that most ovules which outwardly showed 

 nothing abnormal, were yet already in all stages of disorganisation. 



Although we are unable to offer a finished investigation, yet it 

 seemed desirable to us to publish what we have seen. For Dasylirion 

 blooms so seldom in Europe that for us the chance of finishing our 

 investigation is practically nihil, while now at least attention has 

 been drawn to it, so that perhaps in the mother country of the plant 

 some one may feel inclined to re-examine it. 



Moreover the number of known cases of apogamy or partheno- 

 genesis is so small that (here is every reason to publish each new 

 case. And finally the material examined by us presents some points 

 which deserve attention for special reasons. 



The fixed material was embedded in paraffin, cut with the micro- 

 tome and then stained, as a rule with saffranine only, sometimes 

 with saffranine, gentian violet and orange G. 



The ovules of Dasylirion are anatropous and furnished with two 

 integuments ; the outer one consists, besides of an exterior and inte- 

 rior epiderm, of cells, situated rather irregularly in 2 to 4 rows ; 

 towards the chalaza it is much more strongly developed. The inner 

 integument consists of two layers of closely adjacent cells. The 

 micropyle is formed by the inner integument only, the edges of 

 which are strongly swollen — the cells are larger and the thickness 

 is here about four cells — and are closely adjacent, so that they 

 only leave a narrow slit between them. 



The tissue of the nucellus is small-celled near the chalaza, but for 

 the rest it consists of large cells with very little protoplasm and 

 apparently very much cell-sap. The more peripheral cells are smaller, 

 their cell-walls are perpendicular to the integument, especially near 

 the micropyle, but the others are greatly lengthened in the direction 

 of the chalaza so that they have become tube-shaped. These tubes 

 are often more or less bent, so that longitudinal sections present an 

 appearance which is rather difficult to disentangle. The swelling of 



48* 



