18 DR. J. D. HOOKER ON THE STRUCTURE AND 



ferce, and some others ; and from these, through the single-coated ovules of Menispermew, 

 many Monocotyledones, and other Orders, to the double-coated ovule of most Phaenogams, 

 and lastly to the three ovular integuments of Gnetum. 



This rudimentary o\"ule can by no means be compared to the archegonium of a moss ; 

 nor does the reduction of the ovule to its simplest form argue any alliance between Bala- 

 nophorece and Cryptogamic plants. The affinity which Griffith endeavoured to establish, 

 is in this respect founded upon erroneous views of the origin and development of the ovule 

 of Balunophora, mth which he was not acquainted ; and the development of this reduces 

 the grounds of the argument to a casual external resemblance, or rude analogy, between 

 two organs which are not homologous, and have no similarity of origin, structure, or 

 function. 



I very much regret my having been unable to trace the development of the ovule in 

 any of the three embryonate and albuminous genera, Sarcophyte, Mystropetalon, and 

 Cynomorium ; and can only suggest that in them the albumen is endospermic, or deve- 

 loped mthin the embryo-sac, and not in the substance of the nucleus. The jjosition of 

 the radicle in Mystropetalon being close to the hilum of the seed, suggests the probability 

 of the ovule being anatropous, and hence somewhat more complex than its congeners ; 

 whilst the lateral position of the embryo of Cynomorium is consistent with an obliquely 

 pendulous ovule. Until, however, we become acquaiated with the process of impregna- 

 tion or the development of the ovule or the albumen, we have no materials for forming 

 an opinion on the real nature either of the ovule or the seed. I have repeatedly dissected 

 half -grown ovules of Cynomorium preserved in spirits, but never found a trace of any coats 

 to the ovule, which always appeared as a membranous sac, full of cells as in Balanophora, 

 and amongst which cells one is free, and from it the embryo is developed. 



M. WeddeU (Ann. Sc. Nat. ser. 3. v. 14) has also considered the ovule to be an embryo- 

 sac, but he makes this opinion depend upon views of the nature of the ovary, style, stigma, 

 and perianth, so different from my own, as to render our accordance upon this individual 

 point purely accidental. I shall return to this subject after describing the seed. 



Seed. — There are two types of seed in tliis order ; the embryonate, and what has been 

 called by various authors the exembryonate, and wliich has been described as consisting 

 of a homogeneous or sporuliferous mass. The only known embryonate genera are Cyno- 

 morium,, Sarcophyte, and Mystropetalon. 



The seed is always pendulous from the summit of the cavity of the pericarp. The 

 excessively thin testa contracts an intimate but not organic adhesion with the walls of the 

 generally crustaceous endocarp, and is always so closely applied to the surface of the seed 

 that it cannot be detached. This structure is very frequent in various Orders of Exogens, 

 as in Gunnera, whilst there is a manifest tendency to it in Araliacece, Boldoa (a South 

 American genus of Monimiacece), and other plants. In the exalbuminous species the 

 substance of the seed is uniformly cellular ; the cells, which are loose in the ovule, and 

 fill the cavity of the pericarp previous to the swelling of the seed, become densely packed, 

 probably from the cavity being limited in size, and its walls indurated before the seed has 

 arrived at its full growth. When ripe, the seeds of most are densely cox-neous, especially 

 towards the periphery. The comparison of the seed to a loose cellular mass, so frequently 



