304 ON THE PLACENTA OF PRIMULACEiE. 



I had just read in the Enghsh edition of Sachs' ' Text-Book,' 

 ]). 149, that — " Simihir and equivalent lateral members usually arise 

 on the common axial structure in acro^^etal or basifugal order, i. e. 

 the younger a member is the nearer it is to the ai3ex ; counting from 

 below upwards, the members occur in the order of their age. The 

 lateral members which are formed from the X3unctum vegetationis 

 of an axial structm-e sufficiently near the growing apex are 

 apparently always acropetal; but the order is disturbed when 

 lengthening at the a^jex ceases and new formations occur at the 

 primary meristem below, as in many flowers." 



This last-mentioned disturbing influence is not apparent in 

 PniuuhicccB, so that 1 doubted whether the ovules of that order were 

 not all to be looked upon as adventitious, if not trichomic. On 

 p. 497 Sachs says — <' In a few cases the floral axis rises free withm 

 the spacious cavity of the ovary, and produces ovules laterally, as 

 occurs in Priiinihicece,'' illustrating the remark by figures of the 

 floral development of AnagulUs arvensLs, which seem to correspond 

 to Dr. Masters' account of Primula. 



On p. 503 Sachs refers approvingly to Cramer's conclusions 

 that the nucleus is a lateral structure on the funiculus, and that 

 the ovule of Primiilacece being a whole leaf, the nucleus in this 

 order is a formation on its surface, analogous, I suppose, to the 

 common abnormal outgrowth from the midrib of cabbage-leaves. 

 On turning for any further elucidation to Payer's ' Organogenie dela 

 fleur,' I find, on p. 612, the following account of the pistil in Samolus 

 Videyandi : — " Peu de temps apres lanaissance des etamines, le centre 

 de la fleur se deprime et il en resulte une petite excavation, qui est 

 I'origine du pistil. Cette petite excavation n'occupe pas tout le 

 centre de la fleur ; il y a entre elle et la base des etamines une 

 sorte de chemin de halage sur lequel on voit bientot poindre un 

 bourrelet circulaire qui grandit rapidement, et forme une sorte de 

 tuyau de cheminee au-dessus de I'excavation qui, de son cote, est 

 devenue de plus en ^dIus profonde. On a par suite an centre de la 

 fleur un pistil forme a la partie inferieure jpar la coupe recep- 

 taculaire, et a la partie superieure par ce bourrelet devenu 

 style. Pendant que ces modifications se produisent a I'exterieur, 

 le fond de la coupe receptaculaire qui etait d'abord plat se bombe 

 dans son milieu, et il en resulte un tubercule central qui grossit 

 et se recoavre (Vocules du sonimet a la base, en un mot un veritable 

 placente central." The accompanying plates agree exactly with 

 Dr. Masters'. 



It is often the case, as Trecul has shown, that the fibro- 

 vascular bundles are late formations in comparison with the 

 cellular tubercles in which floral organs begin. This is only 

 another way of saying that leaves first appear as a bulging out 

 of the dermatogen, owing to a luxuriant growth of the underlying 

 periblem, and that the extension of the fibro-vascular system into 

 the plerome is a later phase. (See Sachs, op. cit., p. 134). Never- 

 theless with the beautiful figures of Payer and Dr. Masters before 

 one, and remembering what timely service the fibro-vascular 

 bundles rendered Darwin in his unravelling of Orchids, it was 



