[)!' 



PHANEROGAMS. 



sporangia in Lycopodiuin. These explanations are so far confirmed by the occurrence 

 of malformations, that the lateral axial 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. 



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 nucellus 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 nucellus 

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

 shaped lamina of the leaf, growing over the nucellus. 



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

 laceae have no integument ; the nucellus 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^ 



The Develop7nent of the Ovule and of the Embryo-sac^ . [The first indication of 

 the development of the ovule is the division by a wall parallel to the surface 

 (periclinal) of one or more cells lying immediately beneath the epidermis of the 

 placenta^ ; in the case of ovules which have a simple structure when mature, as those 



^ [See Masters, Vegetable Teratology, 1869; and Peyiitsch, Zur Teratologic der Ovula, Fest- 

 schrift d. k. k. Zool.-Bot. Ges. Wien, 1876.] 



^ Hofmeister, Neiie Beitrage, I (Abhandl. der kon. sachs. Gesellsch. der Wissensch. VI). [The 

 remarkable position of the ovule in Hydnora iProtopanche) americana, immersed in the placental 

 tissue, is comparable with that of the sporangium in Isoetes (Fig. 334). It is not possible to 

 say at present if the embryo-sac of Hydnora belongs, like that of the Loranthacese, to an ovule 

 which arises as a prominence on the placenta and is subsequently overgrown by it, or if it is 

 developed from a cell of the placental tissue, the ovule not becoming differentiated from the placenta. 

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

 Soc. vol. XIV. p. 182.] 



2 Hofmeister, Neue Beitrage zur Kenntniss der Embryobildung der Phanerogamen, Abhandl. d. 

 sachs. Ges. d, Wiss, VI, VII, 1859. — [Strasburger, Die Coniferen und Gnetaceen, p. 409; id. Ueb. 

 Befruchtung und Zelltheilung ; id. Ueb. Zellbildung und Zelltheilung, 3rd ed. ; id. Die Angiospermen 

 und die Gymnospermen. — Warming, De I'ovule, Ann, d. vSci. Nat. 1878. — Vesque, Dev. du sac 

 embryonnaire des Phanerogames, Ann. d. Sci. Nat. ser. 6, VI, 1878; id. Neue Untersuchungen, Bot. 

 Zeitg. 1879. — Treub et Mellink, Notice sur le dev. du sac embryonnaire, Arch. Neerlandaises, XV. — 

 Fischer, Zur Kenntniss der Embryosacentwickelung, Jenaisch. Zeitschr. XIV, 1880. — Marshall 

 Ward, Embryo-sac of Gymnadenia conopsea. Quart. Journ. Micr. Sci. XX, 1880; id. Journ. Linn. 

 Soc. XVII, 1880.] 



* [In the fourth German edition, Prof. Sachs, relying upon the observations of Hofmeister, 

 regards the ovules of Orchidese as being trichomes, inasmuch as they are stated by Hofmeister to be 

 developed from single epidermal cells of the placenta. Hofmeister's observations have been shown 

 to be erroneous by Strasburger (Coniferen und Gnetaceen) and by Warming (Joe. cit.). The ovules 



