Cu.\r. n 



EUDIMENTAEY COTYLEDONS 



95 



rig. 61. 



Willi the orange [Ciirvs 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 steni 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 

 liypocotyl was enlarged or swollen. 

 With Abronia umbellafa 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, -jL-th 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 Abronia umbeWda . seed- 

 larger cotyledon ; but as the petiole 

 of the latter increased in length 

 and grew in the same line with 

 the hypocotyl (h), 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 



ling twice natural size: 

 c, cotyledon ; c', rudi- 

 mentary cotyledon ; A, 

 enlarged hypocotyl, 

 with a heel or projec- 

 tion (//) at the lower 

 end ; r, radicle. 



* In Paehira aqiiafica, as de- 

 ecribed Ijy Mr. R. I. Tjynch 

 ('Journal Linn. Soo. Bot.' vol. 

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

 hypogean cotyledons ia of ira- 

 uiense size; the other is small 

 anil snon falls off; the )iair di' nut 

 always stand opposite. In anctiier 



and very different water-plnnt, 

 Trapa mi'ans, one of tlif coUle- 

 doiis, filled with farinaceous 

 matter, is much larger than the 

 other, which is sciircely visible, 

 as is stated by Aug. de Ciindolle, 

 ' Plivsiulogie Veg.' torn. ii. p. 8;^4, 

 1832. 



