2S4 Mr. H. Giraud on the recent Doctrines 



of the nature of phanerogamic generation ; for certainly the 

 investigations of these latter observers lay more claim to our 

 confidence than those of Schleiden, from their having been 

 conducted with greater care, and in a regular chronological 

 order*. But with reference to this question, I believe that 

 an induction may be drawn from a source, which, whilst it is 

 derived from the most universal law of the development of 

 plants, is free from those errors which will ever be found to 

 creep into microscopical investigations, even when conducted 

 by the most skillful hands. 



From the recent additions which have been made to our 

 knowledge regarding the morphology of the reproductive 

 organs, I think it may be shown, that a consideration of the 

 morphological conditions of the ovule and embryo, independ- 

 ent of arguments founded on any other grounds, would lead 

 to the conclusion — that the embryo is originally a body fo- 

 reign to the ovule, and introduced into it from without — a 

 view corroborative of the opinions of Schleiden. 



Most authors make four great stages in the morphology of 

 the sexual system ; — viz. the whorl of the calyx, corolla, sta- 

 mens, and pistil. I think, however, we may make five or 

 even six, by including what I believe to be leaf formations of 

 the ovule. According to these authors, the upper and last 

 stage of metamorphosis is that of the fruit-leaf (carpellary 

 leaf), which, in each of its three dimensions, is changed in a 

 peculiar way. But does the axis terminate with this carpel- 

 lary whorl of leaf metamorphosis? Von Martiusf is of 

 opinion that the axile formation is terminated by the recep- 

 tacle, upon which the fruit-leaf is situated ; so that the elon- 

 gation of the axis is herewith at an end. M. Mohl, found- 



* The very anomalous phsenomena attendant on the embryogeny of San- 

 talum album (so accurately described by Mr. Griffith in the Linn. Trans, 

 vol. xviii. Part I.) are equally opposed to the views of Schleiden; for in no 

 case could Mr. G. perceive the membrane of the embryo-sac either pierced 

 or depressed by the pollen tubes. And, in the cases of Loranthus and 

 Viscum, he found that the formation of the ovule was a process subsequent 

 to impregnation ; — an observation at total variance with the idea that the 

 ovule or female organ is a nidus adapted to the development of an embryo, 

 supposed to be derived entirely and directly from the male. 



f M. Von Martius, Die Metamorphose der Pflanzen, 1837. 



