APPENDIX. BOOK IT. 959 



After the two cotyledons of the developing embryo have made their appearance, an 

 outgrowth, similar to that in Wel<wttschia, is produced at the base of the hypocotyledonary 

 stem ; but in Gnetum its position relatively to the planes of the cotyledons is not fixed, as 

 in IVelivitschia, the point at which it is formed being determined by the action of gravity, 

 so that it always developes on the under side of the hypocotyledonary stem. Further, the 

 organ is larger in Gnetum, and the pith and vascular tissue take part in its formation, 

 whereas in JVel^itschia it is derived only from the cortex and epidermis of the hypocoty- 

 ledonary stem. 



In the three genera of Gnetaceae this organ is developed for the transfer of nutritive 

 material from the seed to the seedling, the size of the organ being proportional to that of 

 the seed and to the quantity of reserve material. 



Page 534, line 2 from bottom (note). For 'Eilcher' read ' Eichler.' 



Page 574. The morphological significance of the ovule. See above, note on the 

 female flowers of Goniferae. 



Page 576. On the development of the ovule of the Loranthaceae, see Treub, 

 Observations sur les Loranthacees, Ann. d. Jardin botanique de Buitenzorg, vols. 2 and 3, 

 Leyden, 1882. 



In Loranthus sphcerocarpus there is, according to Treub, a central placenta which 

 bears three or four free lateral segments; these Treub regards as rudimentary ovules. In 

 each of these several embryo-sac-mother-cells (archesporial cells) are formed, but only 

 one embryo-sac becomes fully developed : it is developed from the uppermost cell of the 

 row formed by the division of the mother-cell. 



In the Viscum album and articulatum there is no placenta and no ovule, but the 

 embryo-sacs are developed in the tissue of the carpels ; in V. album there is a relation 

 between the number and position of the embryo-sacs and the carpels, but in V. articulatum 

 this is not the case. In spite of the degradation of these plants, the mother-cells of the 

 embryo-sacs are nevertheless of hypodermal origin as in the other Angiosperms. 



Page 578, line 8 from top. For ' maculatam ' read ' maculatum* 



In addition to the instances here given of deviation from what may be regarded as 

 the typical mode of development of the embryo-sac, it may be added that in some cases it 

 is the uppermost of the cells of the row formed by the division of the archesporial cell 

 which developes into the embryo-sac, e. g. Loranthus sphserocarpus (Treub), Pyrethrum 

 hahaminatum (Marshall Ward), Agr aphis patula (Treub and Mellink). For the most 

 recent researches on the embryo-sac of Angiosperms, see Guignard, Ann. d. Sci. Nat., 

 s^r. 6, t. XIII, 1882. 



Page 580. The Synergidse. Strasburger (Bau und Wachsthum der Zellhaute, 

 1882) considers that the longitudinal striation (Filiform Apparatus of Schacht) mentioned 

 in the text is due to the presence of delicate canals which are filled with protoplasm ; the 

 body of the Filiform Apparatus is probably not protoplasmic. 



Page 588. Development of the Embryo. See also Rech. embryol. sur V Orchis 

 maculata, Monteverde in Melanges Biologiques de I'Acad. Imp. de St. Petersbourg, 1880; 

 Guignard, Rech. d'embryogenie veg6tale comparee, Ann. d. Sci. Nat., ser. 6, t. XII ; and 

 Treub, Notes sur I'Embryon, le Sac embryonnaire, et I'Ovule, in Ann. d. Jardin bot. de 

 Buitenzorg, III, 1882. 



Treub's researches refer to Peristylus grandis and to A'uicennia officinalis. With 

 regard to the former he finds that the embryo remains at first rudimentary, whereas the 

 suspensor grows rapidly and until it projects through the micropyle ; it then branches, 

 and the branches become closely applied to the placenta. At this time the embryo begins 

 to develope, and there is no doubt that it does so in consequence of the supply of nutritive 

 material which is absorbed from the placenta and transmitted by the suspensor. These 

 observations confirm Treub's previous conclusions as to the function of the suspensor in 

 Orchids. 



With regard to Avicennia, Treub's observations complete our knowledge of this 

 curious 'viviparous' plant long ago described by Griffith (On the development of the 



