Chap. II 



KUD1MENTAE5 COTYLEDONS 



95 



Fig. 61. 



With the orange {Citrus aurantium) the cotyledons are 

 hypogean, and one is larger than the other, as may 

 be seen in A (Fig. 60). In B the inequality is rather 

 greater, and the stem has grown between the points 

 of insertion of the two petioles, so that they do not 

 stand opposite to one another; in another case the 

 separation amounted to one-fifth of an inch. The 

 smaller cotyledon of one seedling 

 was extremely thin, and not half 

 the length of the larger one, so that 

 it was clearly becoming rudimen- 

 tary.* In all these seedlings the 

 hypocotyl was enlarged or swollen. 

 With Ahronia umhellaia one of 

 the cotyledons is quite rudimen- 

 tary, as may be seen (c) in Fig. 61. 

 In this specimen it consisted of a 

 little green flap, -aVth inch in 

 length, destitute of a petiole and 

 covered with glands like those on 

 the fully developed cotyledon (c). 



At first it stood opposite to the Abrmta umbellata : seed- 

 larger cotyledon ; but as the petiole iingtwjce naturaUize: 

 ^ ■' ' . ^ e, cotyledon ; c , rudi- 



of the latter increased m length mentaiy cotyledon ; a, 



and grew in the same line with 



the hypocotyl Qi), the rudiment 



appeared in older seedlings as if 



seated some way down the hypocotyl. With Ahronia 



arenaria there is a similar rudiment, which in one 



enlarged hypocotyl, 

 with a heel or projec- 

 tion (A') at the lower 

 end ; r, radicle. 



* In Pachira aquaiica, as de- 

 scribed by Mr. E. I. T^ynch 

 ('Journal Linn. Soc. Bot.' vol. 

 xvli. 1878, p. 147), one of the 

 hypogean cotyledons is of im- 

 mense size ; the other is small 

 and soon falls off; the pair do not 

 always stand opposite. In another . 



and very different water-plant, 

 Trapa nutans, one of the cotyle- 

 dons, filled with farinaceous 

 matter, is much larger than the 

 other, which is scarcely visible, 

 as is stated by Aug. de CandoUe, 

 ' Phvsiologie Veg.' torn. ii. p. 834, 

 18.32. 



