252 PHILOSOPHICAL NOTES ON 



Some consider the nucellus (or body of the ovule) as a part or 

 tooth of this leaf (Reissek) ; others think it a new creation. In 

 the latter ease it is sometimes regarded as a bud (Caspary, 

 Rossmann, incline to it) ; sometimes as a metablasteme ; and 

 latterly as the homologue of a sporange (Brongniart, Cramer, 

 Van Tieghem* and Celakovsky). I incline to the latter view," says 

 Warming, "- and I understand that Eichler does so also. Some 

 observers think the ovule admits of a different interpretation, 

 according as it is on the extremity of the axis or on a leaf . With 

 Celakovsky, I however, recognize that the morphological significa- 

 tion of an organ does not absolutely depend on its position." 



In his final resume, p. 251, Warming says : " The theory 

 that the ovule is a bud is supported by the terminal position of a 

 great number of ovules, which makes them appear as emerging 



directly from the axis nevertheless (p. 254)," 



the theory of Brongniart is much more admissible. 



First. Because carpels and placentas are phyllomes, and 

 therefore it is difficult to admit that ovules are buds. (!) It is true 

 that buds can grow on leaves, but to admit that ovules were similar 

 buds regularly borne on the carpellary leaf would require reasons 

 of great weight. (!) 



Second. Teratological specimens show us that the ovule is 

 always transformed into a lobe of a leaf, on which the nucellus is a 

 new creation, as an outgrowth. Sometimes there are two nucellif 

 on the same ovular leaflet. 



Third. The development of the nucellus is so like that of the 

 pollen-sac of Angiosperms that there is no doubting their homo- 

 logy,! ^^^ ^^® pollen- sac is homologous with the sporange, there- 

 fore, the nucellus is comparable to a macrosporange or ovule. 



. . . Finally, as pollen-sacs are borne on leaves ; as this is 

 also true of the ovule ; as the sporange of cryptogams, the common 

 and original form of the reproductive organs of phsenogams, are 

 also borne on leaves, we must admit, in a general way, that the 

 reproductive organs of all vascular plants are borne on leaves, and 

 that morphologically they are metablastemes." 



All this controversy about whether the ovule is a bud, or a 

 lobe or tooth of a leaf, becomes obsolete the moment we recognize 



* The nucellus is a sort of large hair which the leaflet embraces as in a 

 cupnle. (In the onginal this is a foot-note under the name of Van Tieghem.) 

 f Vide glands on Cherry leaf (stamen and anther). 



