EXPLANATION OF THE PLATES. 
569 
Fig. 23. Very young ovulum of Ruta graveolens ; a, the priinine ; 6, the se- 
cundine ; c, the nucleus. In the end, the primine extends, contracts at its 
foramen, and closes over the secundine and nucleus. 
Fig. 24. Vertical section of an ovulum of Alnus glutinosa : a, the umbilical 
cord ; 6, foramen ; c, primine (and secundine perhaps united with it) ; d, nu- 
cleus ; e, vessels of the raphe ; f, place of the chalaza. 
Fig. 25. An oblique vertical section of the fertilised ovulum of Tulipa Ges- 
neriana : a, foramen of the primine (or Exostome) ; 6, foramen of the 
secundine (or Endostome) ; c, primine; c?, secundine ; e, nucleus, its apex 
concealed within that of the secundine; f, vessels of the raphe; g, place of the 
chalaza. 
Fig. 26. Ovulum of Lepidium ruderale; after A. Brongniart : a, umbilical 
cord ; 6, foramen ; c, point of the nucleus seen through the primine and 
secundine. 
Fig. 27. Half-ripe seed of the same, cut through perpendicularly ; after Bron- 
gniart : a, the umbilical cord ; 6, foramen ; c, primine ; d, secundine ; e, nu- 
cleus ; /, embryo partially formed, its radicle pointing to the foramen ; g, the 
point where the nourishing vessels of the placenta expand (the chalaza). 
Fig. 28. A perpendicular section of the ripe seed of the same ; after A. Bron- 
gniart. The primine and secundine are consolidated, and the nucleus is 
entirely absorbed by the embryo, a, Umbilical cord ; 6, foramen, now become 
the micropyle ; g, chalaza ; cotyledons of the embryo ; i, radicle ; k, 
plumula. 
Fig. 29. Mode of fertilisation in Cucurbita Pepo ; after Adolphe Brongniart : 
а, a portion of the placenta; 6, ovulum; c, its foramen ; d, the bundle of stig- 
matic tissue through which the fertilising matter is conveyed, and to which the 
foramen is closely applied ; e, the bundle of vessels that communicates with the 
umbilicus ; f, the commencement of the raphe. 
PLATE VI. 
Fig. 1. A, Vertical section of the seed of Canna lutea : a, albumen ; h, embryo. 
— B, Embryo extracted and divided vertically : a, cotyledon ; h, plumula con- 
cealed within the embryo ; c, radicle, with internal rudiments of roots. 
Fig. 2. A, Vertical section of the seed of Myrica cerifera : a, cotyledons ; 
h, radicle ; c, plumula ; d, remains of foramen ; e, hilum. — B, Embryo ex- 
tracted entire : a, cotyledons ; 6, radicle. 
Fig. 3. Vertical section of the seed of Luzula campestris ; a, albumen ; 
б, embryo. 
Fig, 4. Vertical section of the grain of Bromus mollis : a, albumen ; 6, embryo; 
c, its plumula ; c?, its cotyledon ; e, its radicle, with internal rudiment of a 
root. 
Fig. 5. Vertical section of the seed of Rheum rhaponticum : a, albumen ; 
bf embryo ; c, hilum ; d, remains of foramen. 
Fig. 6. A, Seed of Triglochin palustre : a, fungous chalaza ; 6, raphe ; c, 
hilum. — B, Embryo of the same : a, cotyledon ; b, radicle ; c, fissure, 
within which the plumula lies. — C, The same halved vertically; a, cotyledon; 
6, radicle ; c, fissure ; d, plumula. 
Fig. 7. A, Seed of a species of Begonia : a, hilum, — B, The dicotyledonous 
embryo. 
