2.3G Mr. H. Giraud on tlie recent Doctrines 



structure, (meaning the ovules with their embryos,) which 

 separate from the primitive axis, and commence an inde- 

 pendent life ; but it is impossible to reconcile this with his 

 former statement — that the axis terminates at the receptacle. 

 If it be conceded that the axis is prolonged into the ovarium, 

 and has its Bhare in the formation of the placenta, then may 

 we conclude that the ovule itself is an axile formation, and 

 that it is in all respects analogous to a leaf-bud; hence the 

 ovular membranes, inclosing the nucleus, must be collateral, 

 or true leaf formations. The correctness of this view may be 

 moreover established on the following grounds. The primine 

 and secundine, at a very early period of their development, 

 are not presented each as a continuous membrane encircling 

 the nucleus, but they consist of several portions, forming 

 two whorls of what I would term ovular leaves, their inter- 

 node being wanting ; its normal position being occupied by 

 a portion of tissue near the chalaza. This opinion is also 

 supported by the instances which have been noticed of the 

 descending metamorphosis of the ovule. MM. Henry and 

 Marquart have noticed the retrograde or descending metamor- 

 phosis in the ovules of the Salicc cinerea, and have represented, 

 in drawing, a catkin, the carpels of which were filled with a 

 number of longitudinally folded leafs occupying the normal 

 situation of the ovules ; doubtless these were the organs 

 which should have constituted the ovular membranes. Hence 

 then it may be concluded that the axis has its termination at 

 some point within the ovule ; this I would consider to be 

 situated at the chalaza ; here, the vessels which have ascended 

 through the woody tissues of the stem, and have penetrated 

 the cellular structure of the placenta, are suddenly stopped, 

 as it were, in their course, and are spread out in ramifications 

 to the nucleus and its tegumentary membranes; thus form- 

 ing the true organic placenta. 



It has been asserted by Turpin* that the axis has its ter- 



* Esquisse d'Organographie Vegetale, fondee sur la principe d'unite et de 

 composition organique et devolution rayonnante ou centrifuge, pour servir 

 a prouver l'identite des organes appendiculaires des vegetaux, etla metamor- 

 phose des plantes de Goethe. Paris, 1837. 



