PINE REPRODUCTIVE ORGANS 255 



separated from one another, so as to disclose the seeds, 

 two of which are borne at the base of each of the 

 ovuliferous scales. These ripe cones are seated laterally 

 near the apex of the two-years-old shoot. 



I. Cut median longitudinal sections of a cone 

 corresponding to stage (a). It should previously, 

 have been hardened with alcohol for some days : 

 mount in glycerine, and examine with a low power. 

 Observe 



1. The central axis, not differing essentially from the 

 young vegetative axis : on this "are borne scales of two 

 orders easily distinguished by their size. 



2. The smaller of these are the leaves borne by the 

 axis of the cone, and the morphological equivalents of 

 the brown scale-leaves which cover the winter buds. 



3. In the axil of each of these is borne one of the 

 larger or ovuliferous scales, which are longer and 

 more bulky than (&) : they alone can be seen externally. 

 On the upper surface of each of these, close to the axis, 

 are borne 



4. Two ovules, or macrosporangia, which are 

 anatropous, so that the micropyle is directed towards 

 the base of the scale : if cut in a median plane, each 

 ovule will be seen to consist of 



i. One integument, several layers of cells in thick- 

 ness, with a widely open micropyle facing the axis : 

 this surrounds 



ii. The nucellus, a mass of parenchyma, near the 

 centre of which is 



iii. The embryo-sac or macrospore, a cell much 

 larger than those of the surrounding tissue, and lying 

 some distance below the apex of the nucellus. 



