474 



CONSERVATIVE ORGANS. 



[LECT. ix. 



down as represented at a. in 

 the marginal cut ; and the sti- 

 pules, as they are termed, which 

 are flat foliaceous plates (see b. 

 which is one of them separated 

 to show its form and vessels), 

 form a bivalve case for it, con- 

 taining at the same time all 

 the younger leaves, each arched 

 and enclosed in a similar man- 

 ner. As soon as the leaf is capable of bearing the 

 exposure, the two plates of the case separate, 

 bending down as at c. c. and in a short time drop 

 off; meanwhile the footstalk of the leaf becomes 



straight and the disk is 

 spread out to the light 

 and air. In some in- 

 stances this covering is 

 univalvular and sepa- 

 rates at the base, at the 

 same time that it opens 

 laterally, as exemplified 

 in the Magnolias; and 

 I very elegantly in the 

 Elastic-gum tree, Fie us 

 elastica; the sheath of 

 which (see fig. 1. a. in 

 the marginal cut) is of 

 a deep red colour, 



