50 NOTES AND MEMORANDA. 



whicli the same physiological functions can be exercised by organs 

 which are very different morphologically, and it has hence been con- 

 cluded that that must be true for the ovule — though it may be possible, 

 it does not necessarily follow that it is so. I pass by this illogical 

 reasoning, therefore, until there has been discovered a well-estab- 

 lished fact showing that the functions of the ovule are fulfilled by 

 an organ which cannot be assimilated to a sporangium. A. Brauu 

 recognizes " that an organ analogous from a phylogenetic j^oint 

 of view to a sporangium developed on a leaf, and to the pollen sac 

 of the staminal leaf, should be considered as an excrescence of the 

 carpel ;" but he adds that " in its ulterior development it may be ele- 

 vated to the dignity of a vegetative point j^roducing some leaves in the 

 form of sheaths destined to protect the organ of reproduction which is 

 formed on the vegetative summit itself." In other words, that an 

 organ of any morphological nature whatever may be transformed into 

 another of superior dignity. These considerations are so wanting iu 

 foundation, they are so opposed to observed facts, that I can see nothing 

 else on the part of the celebrated mori:)hologist than an attempt to 

 sustain, notwithstanding its contradictions, a favourite theory, but one 

 nevertheless that cannot be supj^orted. 



II. I sum up briefly my results and my arguments, in comparing 

 the different ovular theories. 



The theory according to which the ovule is a bud has found support 

 in the terminal position of a great many ovules, which makes them 

 appear as the direct continuation of the axis. But M. Celakovsky has 

 shown that the terminal j)osition (or generally any position whatever 

 of an organ) cannot demonstrate its morphological value, since there 

 exist, for example, terminal leaves. He has j)roved that the part of the 

 pistil which carries the ovule is everywhere of a foliar nature, even in 

 the case of a central free placenta. In this he is of the same opinion 

 as M. Van Tieghem, who has pursued an entirely difterent line. I 

 agree in this opinion, and I have endeavoured to show that the history 

 of development, in general very ineffective iu similar questions, teaches 

 us that the placenta or the terminal ovule in certain cases is a new 

 creation on the summit of the axis. Amongst the Gymnosperms we 

 find at first in the Cycadacese true carpellary leaves, and it has been 

 established that the scales which bear the ovules in the Abietinese are 

 of a leafy nature, even when the scale cannot be interpreted as the 

 fertile ventral part of the protecting scale, as I have mentioned hypo- 

 thetically in my work on the Cycadaceie. The concordances in the 

 structure and anatomy enable us to admit that it is true also for the 

 other Conifers (with non-terminal ovule). For the Gingl-o the ovular 

 organ situated in the axil of the scales of the bud or of the leaves, 

 must be considered as being comj)osed of two leaves joined together, 

 belonging to an axillary bud, like the needle of Sciadopitijs. The two 

 parts are even placed in the same manner, the physiologically lower 

 face being turned towards the principal axis. Amongst the Cupres- 

 sinesB and other Conifers with scales apparently simj^le, the union of 

 two organs must be admitted, with MM. Van Tieghem and Strasburger. 

 I admit that I am not able to apprehend in all its details the disposi- 



