144 



Elementary Botany 



surrounded by the endosperm, as in the Pansy (fig. 289), the 

 former is said to be central, and the latter peripheric. 



The case is just reversed in the Mirabilis Jalapa (fig. 290), 

 where the peripheric embryo is bent round the central endo- 

 sperm. 



At other times the embryo and albumen are placed more 

 side by side, when they are said to be lateral. 



III. 



Fig. 292.-1., 



II., III. Develojjment of the arillus of the Yew. 

 tion through the ripe seed. 



IV. Longitudinal see- 



In some plants a peculiar appendage is developed from the 

 hilum of the ovule after fertilisation, and, growing up round the 

 seed, forms either a complete coat as in the Yew (fig. 292), a 

 perforated coat as in the ' mace ' of the Nutmeg, or hairs as 

 in the case of the Willow. This is known as the arillus. 



