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Botany. — " 'rhe devclopiiwiLt of tlw ontlc, finbryo-mc (tnd tufij in 

 Podostem<iceae\ By Prof. F. A. V. d. Wknt. 



During my voyage to llie Weist-Iiidies I had an opportunity of 

 visitiug ill Surinam some of the rapids where Podostemaceae grow, 

 namely the Armina fiills of the Marowyne river. There I collected 

 material of these remarkahle j)hiiits, and at a later date 1 received 

 an abundant supply obtained by the various ex|)editioiis, which of 

 late years have investigated the interior of the colony. This material, 

 preserved in alcohol, has suggested to mc an investigation of the 

 above order. 1 hope soon to publish the residts oi c.rtenso, but wish 

 in this place to deal briefly wilii one ])oint, namely the development 

 of the ovtile, the embryo-sac and the egg. 



As was mentioned above, the material was fixed in alcohol, 

 but the tixation nevertheless ju'oved to be good enough to allow 

 of mauy cytological details beiug made out with a sufficient degree 

 of certainty in stained preparations. In this j)relimiiiary communica- 

 tion I do not propose to discuss the method of treatment of the 

 preparations, but merely record, that Messrs. A. H. Blaauw and 

 J. KuYPEK have assisted me. A comj)lete develojunental series could 

 only be obtained in the case of a few sj)ecies, namely of Oenone 

 [mthurvl (joehel and Mourent jliirintilU AuhJ. Of eight other species 

 only a few stages of the development were examined, and of 7Vw«'«'Art 

 hypnoideK Spr. I only had the ripe seeds. 



It soon became evident that the whole developmeut of the ovule 

 in this order departs very widely from the ordinary type of Am/io- 

 ^Iternis, but that within the Hunts of the order there is an extra- 

 ordinary degree of uniformity, so that tiie differences between the 

 species, which have been investigated, are so slight, that they may 

 be passed over in silence in this preliiuinary notice. The description 

 which follows, therefore applies to all the species. 



The ovules are anatropous ; in the youngest stage examined, the 

 curvature had already taken place. In this stage the nucellus was 

 still alone present and consisted of a central row of four cells sur- 

 rounded by a single layei- of peripheral cells. Of the central row 

 the uppermost cell, which is therefore still surrounded by a cap of 

 epidermal cells, becomes the spore mother-cell. Accordingly this cell 

 is not only soon distinguished from all the other cells of the nucellus 

 l»y its si/.e, but also by its dense jn'otoplasmic contents and by its 

 large nucleus. The subseipient behaviour of this spore mother-cell 

 will be further discussed below. 



We may now consider how the integuments are formed. The 



