of the Embnjos in the Seeds of Coniterpe. 373 



hazards tlic conjecture that the grains of pollen enter and become 

 the future embryos. This, in vvgard to Cr/cas, might be considered 

 the revival of the general hypothesis ad\anced by jMorland in 

 1703*, and some years afterwards adopted, but without acknow- 

 ledgement, by C. J. Geoffroyt, and which seems to have entirely 

 originated in the discovery by Grew of the existence of a foramen 

 opposite to the radicle of the embryo in the ripe seeds of some 

 Leguminous plants J. 



But as jM. du Petit Thouars had evidently no intention of ex- 

 tending his hypothesis beyond Cycas and probably Zinnia, it can 

 hardly be said to anticipate the general and ingeniously sup- 

 ported theory of Dr. Schleidcn, respecting which physiological 

 botanists are at present almost equally divided. On this theory 

 it is not my intention at present to express an opinion ; nor did 

 the question of the mode of action of the pollen form any part of 

 my object in the preceding essay. I shall only here remark, that 

 according to the latest statements of Dr. Schleiden with which I 

 am acquainted^, although he admits that his investigation is not 

 in all points complete, he seems to have no doubt that his theory 

 of the origin of the vegetable embryo in the pollen tube is appli- 

 cable to Conifercp. lie has in the fii"st place ascertained the ex- 

 istence of my areolffi or corpuscula, which he denominates large 

 cells in the embryo-sac or albumen, in all the European genera 

 of ConifercE\\; and in Abies excelsa, Taxus baccata, and Juniperus 

 Sabina, he states that he has succeeded in preparing free the whole 

 pollen tubes from the nucleary papillae to the bottom of the cor- 

 puscula. But as (if my observations are correct, and they seem 

 to be confirmed by those of M. de Mirbel) the corpuscula are not 

 developed in Pinus, as the genus is at present limited, until the 

 spring or even beginning of summer of the year after flowering, 

 and if Dr. Schleiden's statement be also correct, the pollen must 

 remain inactive for at least twelve months. 



The quiescent state of pollen for so long a time is indeed not 

 altogether improbable on considering the analogous occonomy in 

 several tribes of insects, in some of which the male tiuid remains 

 inactive in the female for a still longer period 1[; and in plants, 

 though for a much shorter period, I may refer to Goodenoria, 

 in which the pollen is applied to the stigma a considerable time 

 before that organ is sufficiently developed to act upon or transmit 

 its influence**. But the supposed protracted state of inactivity 



* Philosophical Transactions, vol. xxiii. part 2. n. 287. p. 1471. 

 t Mem. de I'Acad. des So. de Paris, 1711, p. 210. 



I Anat. of Plants, p. 2. § Schleiden, Grund. der Eot. 2 Thcil, p. 374. 



II Op. cit. pp. ;3o4 et 357. 



^ Herold. Entwickel. der Schmetterl. &c. 1815, et Siebold in Miillcr's 

 Arehiv, 183/, p. 392. 



** Append, to Flinders's Austral, p. 560, 



