278 



MANUAL OF BOTANY 



generally peripheiical, become also approximated, and it is said 

 to be amphitropous. When we wisli to know the direction of 

 the embryo, it is at once determined by ascertaining the position 

 of the hiluin, chalaza, and mieropyle. 



We have now lastly to explain the diflerent terms which are 

 in use to express the relations which the embryo bears to the 

 cavity or cell in which it is placed. The radicle is said to be 



Fig. 606. 



Fig. 60.5. 



Fig. 608. 



Fig. G05. VerticEil section of the fruit of the Nettle, contaiuiug a single 

 seed. t. Internments of the seed. pi. Placenta. i\ Radicle, st. Stigma. 

 Fill. 606. Vertical section of the fruit and solitary erect orthotropous 

 seed of the Dock (Rume.r). ov. Pericarp, mic. Mieropyle. pi. Emhryo 

 which is inverted or antitropous, and turned towards one side of the albu- 

 men, alb. ch. Chalaza. r. Radicle. Fig. 607. Vertical section of the 



carpel of Mirahilis Jalapa, containing one seed. a. Pericarp, s. Style. 

 e. Peripherical embryo with its radicle, i\ and cotyledons, c. p. Albu- 

 men, t. Integuments of the seed. Fitj. 608. Vertical section of the seed 



i)f Ltichvt^ dioica. te. Integuments, emh. Embryo on the outside of the 

 albumen, olh. The etnbryo is amphitropous and peripherical. 



superior or ascending, as in the Nettle (fig. 605, r) and Buinex 

 (fig. 606, r), when it is directed towards the apex of the cell or 

 pericarp ; inferior or descending when it points to the base ; 

 centripetal if turned inwards towards the axis or centre ; and 

 centrifugal when it is turned towards the sides. These rela- 

 tions of the embryo to the other parts of the seed and to the 

 cavity or cell in which it is placed, are sometimes of much prac- 

 tical importance. 



