658 



covered by the strap-like funiculus previous to fecundation, and the 

 funiculus subsequently pushed aside by the protrusion of a cellular 

 body proceeding from the base of the styles, I find that previous to 

 the expansion of the flower this cellular body is intimately united to 

 the apex of the secundine of the ovulum, and remains thus attached 

 until fecundation is effected, (see fig. 1 and 2) : consequently the fu- 

 niculus, in every stage, occupies a lateral position. At the exact pe- 

 riod of fecundation there is reason to believe that the cellular body 

 penetrates the apex of the nucleus by a very minute aperture ; because 

 when the embryo just becomes visible within the nucleus at its apex 

 (suspended from a mass of spongy cellular tissue), there is sometimes 

 to be seen a hair-like process terminating the cellular body (now dis- 

 united from the secundine, and by its shrinking, at some distance 

 above it) as though a pollen- tube had passed down from above into 

 the nucleus. Those who hold the views of Schleiden will find the 

 appearances extremely plausible, (see iig. 5). The cellular body, as 

 it appears at the time of fecundation (see fig. 4) is such as to induce 

 the supposition that the vesicular body {d) may be the origin of the 

 embryo, and may also perhaps be the bulbed extremity of a pollen- 

 tube ; but this is at variance with all that I have yet witnessed in other 

 tribes. The part markedy (magnified about 300 times) appears to be 

 the truncated extremity of a tube which may have been continued 

 into the nucleus, the apex of which consists of loose cellular tissue, 

 and may have a very minute aperture ; but this, as well as the aper- 

 ture of the secundine, can be very imperfectly made out by actual 

 observation. That the hair-like process of the cellular body (fig. 5) 

 has in some way penetrated into the nucleus is almost certain, and 

 need not be disputed. 



At fig. 3, the embryo is shown as it appears shortly after fecunda- 

 tion. The upper body within the nucleus is a mass of spongy cellu- 

 lar tissue, and the roundish body below is the embryo, with its two 

 wide-spreading lobes (not seen in the figure from its position), which 

 form the cotyledons when the embryo has filled up the cavity of the 

 nucleus. Previous to fecundation the nucleus has no trace whatever 

 either of the embryo or of the cellular tissue from which it is suspend- 

 ed. It constitutes the albumen of the perfect seed, and is much thick- 

 ened towards the lower part. 



Plants belonging to the order Plumbagineae are remarkable for hav- 

 ing five styles or pollen-ducts and only one ovulum. Assuming that 

 the embryo is formed by the extremity of a pollen-tube, what is to pre- 

 vent the occasional presence of two or more embryos in the ovulum ? 



