600 APPENDIX. 



Figs. 5. and 6. Martynia diandra. 



Fig. 5. Longitudinal section through the seed-bud, a, Simple integument ; 

 b, the remaining epidermis of the nucleus ; c, the sac of the embryo already filled 

 with a delicate endosperm ; d, the pollen-tube which runs almost through the 

 whole length of the embryo-sac to the base of the seed-bud ; e, raphe. 



Fig. 6. Pollen-tube prepared from the foregoing : b, a large globular cell which 

 forms the foundation of the future embryo; lying under this cell are some others, 

 which form the peduncle of the embryo. 



Figs. 7. and 8. CEnothera r/rizocarpa. 



Fig. 7. Longitudinal section through the seed-bud, a, External ; b, internal 

 integument ; c, nucleus ; d, sac of the embryo ; e, pollen-tube. 



Fig. 8. Pollen-tube separated from the foregoing, , Internal integument ; 

 b, nucleus ; c, sac of the embryo; d, pollen-tube, which in passing through the 

 internal and external integument exhibits irregular bulgings and contractions, in 

 order to pass through the inner foramen of the seed-bud. It then again be- 

 comes broader (e) as it passes through the nucleus, and at/ presents a considerable 

 enlargement (which subsequently becomes the peduncle (g) of the embryo); it 

 then again contracts, and at last terminates in a little vesicle which eventually 

 becomes the embryo. As the pollen-tube contains in its sap a good deal of 

 albumen, it becomes coloured of a dark yellow colour, and almost opaque, when 

 treated with tincture of iodine. 



Figs. 9 1 1. Momordica Elaterium. 



Fig. 9. Transverse section of the germen. <z, The seed-buds, which are repre- 

 sented in the following figure : 



Fig. 10. Longitudinal section through a seed-bud and a part of the spermophore ; 

 a, conducting cellular tissue ; b, peculiar group of spiral vessels in the spermo- 

 phore ; c, external ; d, internal integument ; e, nucleus ; /, sac of the embryo ; 

 g, pollen-tube. 



Fig. 11. Point of the nucleus prepared from the foregoing : e g, as in the pre- 

 vious figure. In the embryo-sac are visible cell-nuclei and young cells, the 

 commencement of an endosperm. The pollen-tube, before its entrance into the 

 seed-bud, forms a considerable irregular enlargement ; it then passes through the 

 elongated nipple of the nucleus, and forms a very considerable vesicular enlarge- 

 ment in the embryo-sac, which is the foundation of the future embryo. 



