ANGIOSPERMS. ^05 



only to single families or genera. If these facts are compared with what occurs in 

 Gymnosperms, the ovules of Cycadese must be classed with the marginal carpellary, 

 those of many Cupressineae with the superficial description ; while those of Taxus 

 are axile and terminal, and those of Salisburia lateral. 



When the position of the ovules is given, so also is in general their morpho- 

 logical significance : the terminal ovules must be regarded as the terminal portion 

 of the axis, the lateral as equivalents of whole leaves, the marginal as branches of 

 leaves (laciniae, pinnae, or lobes); the superficial ovules may be included in the 

 category of such foliar outgrowths as we have already found to occur in the form 

 of sporangia among the Lycopodiaceae^ The ovules of Orchidese must however 

 be included (like the sporangia of Ferns and Rhizocarps), under the category of 

 trichomes, inasmuch as they owe their origin to single superficial cells of the 

 parietal placentae (according to Hofmeister) and have no fibro-vascular bundles in 

 the funiculus. These explanations are so far confirmed by the occurrence of 

 malformations, that the lateral axile and the marginal carpellary ovules are often 

 enough transformed into foliar structures of ordinary form, while this appears 

 never to occur with terminal or superficial ovules, or with those of Orchideae. 



These remarks have at present been confined to the ovule as a whole, although 

 reference has already been made to the theory of Cramer on the various morpho- 

 logical relationships of the nucleus and of the other parts, the funiculus and the 

 integuments. Malformations, which in this respect are even more instructive than 

 the normal development, led Cramer to the conclusion that when the ovule appears 

 to be the equivalent of a lateral branch or of the whole of a leaf, the funiculus and 

 the integuments together correspond to the foliar structure in each case ; the 

 nucleus arises from it as a lateral outgrowth, while the integuments correspond to 

 the hood-shaped lamina of the leaf, growing over the nucleus. The integument 

 of a terminal ovule would therefore be equivalent to a leaf on the axial nucleus" 

 (see also Hanstcin and Schmitz, /. c). But we cannot enter further here into 

 these relationships. 



The ovules are sometimes rudimentary; those of Balanophoreae and Santa- 

 laccae have no integument; the nucleus is naked, and in some species is itself 

 composed of only a few cells. In Loranthaceae the development does not even 

 proceed so far as the formation of a distinctly differentiated ovule ; the growth of 

 the apex of the floral axis ceases so soon as the carpels begin to be formed ; 

 and the cohesion of these is such that it is scarcely possible to speak of a cavity of 

 the ovary; the formation of the embryo-sac in the axial part of the tissue of the 

 inferior ovary is the only indication that this spot corresponds to the ovule ; and 

 since more than one embryo-sac is formed, it still remains doubtful whether this mass 

 of tissue must be regarded as the equivalent of one or of several ovules^. 



1 [The remarkable position of the ovule in Hydnora (Prosopancke) americana, immersed in the 

 placental tissue, is comparable with the origin of the sporangium in Isoetes (Fig. 306, p. 408). On 

 Hydnora see De Bary, Abhandl. der naturf. Gesellsch. zu Halle, vol. X ; Hooker, Journ. Linn. Soc. 

 vol. XIV, p. 182.— Ed.] 



2 In this one case the ovule might be a bud in the ordinary sense of the word; i.e. the young 



state of a leaf-bearing axis. 



3 Hofmeister, Neue Beitrage I (Abhandl. der kon. sHchs. Gesellsch. der Wissensch. VI). 



