34 ON SEEDLINGS 



the other the outer side of the curve ; and, as shown in fig. 67, 

 the outer one is distinctly larger than the other. 



In Thunbergia reticulata the cotyledons are unequal, ovate, 

 obtuse, slightly emarginate, and cordate at the base. The 

 larger one is slightly denticulated, and has a curious embossed 

 area in the centre ; the smaller one is, on the contrary, 

 smooth and entire, or nearly so. The seed is orbicular or 

 oblong; exalbuminous, 3-4 mm. in diameter, compressed, 

 with a cavity on the inner side. The embryo is slightly 

 curved ; and the cotyledons lie with their faces towards the 

 hilum, which is very prominent ; the inner cotyledon is turned 

 up at the edges, and wraps, to a certain extent, round the 

 outer one. The raised or embossed patch in the centre of 

 this cotyledon is due to the inward curvature of the testa. 



UNSYMMETRICAL COTYLEDONS. 



In other cases, as in the Geraniums (fig. 25), Schinus 

 (the False Pepper) (fig. 28), Clitoria (fig. 27), Laburnum (fig. 

 26), Lupines, &c., there is inequality, not between the two 



FIG 68. Section through embryo FIG. 69. Seed of Laburnum 



of Geranium, showing the mode vulgare, x 6 : OC, outer 



of folding of the cotyledons. coat ; 1C, inner coat. 



cotyledons, but between the two halves of each cotyledon. In 

 the Geraniums this is due to the manner in which the coty- 

 ledons are folded. In the Cabbage and Mustard we have seen 

 that one cotyledon is folded inside the other ; in the Geranium 

 they are convolute (fig. 68), one half of each being folded 

 inside one half of the other the two inner halves being the 

 smaller, the two outer the larger ones. 



In the Laburnum (fig. 26) and in Clitoria (fig. 27), on the 



