138 



Transactions of the Society. 



margin of the scale ; in the Cypresses, on the other hand, towards 

 the free margin, and away from the axis of the cone. 

 The cotyledons are often numerous. 



In the Ginkgo tree (Ginkgo biloba) the integument of the seed 

 becomes succulent and is of a bright orange colour. It is a remark- 

 able species in many ways. It possesses mobile antherozoids,* a pro- 

 vision which does not, so far as we know, occur in any Phanerogams, 

 or in any other Gymnosperms except Cycas and Zamia. They 

 swim by means of cilise. 



Pinus sylvestris (the Scotch Pine). — The fruit is a cone, consist- 

 ing of more or less hardened, imbricated scales, each protecting 

 two winged seeds (fig. 20). These are easily transported by the 

 wind, and the cones themselves are often carried by squirrels and 

 birds. The scales are more or less thickened, or " umbonate," 



at the apex, and especially on the outer 

 aspect. 



The cones take two years to ripen, and 

 often remain for several more attached to 

 the tree. Sooner or later, however, the 

 scales open in dry and warm weather, 

 liberating the seeds. These are produced 

 into a wing four or five times as long as 

 the seed itself. The wing is straight on 

 one edge, and more or less curved on the 

 other. This form is due to there being two 

 seeds to each scale. 



The texture of the wing is very thin, 

 pale brown, subtransparent, and finely 

 As in many other cases where there is a 

 single wing, the centre of gravity is excentric, which gives the 

 seed a spinning motion, and thus facilitates its passage through 

 the air. 



In several species of Pine, as, for instance, in P. serotina, the 

 scales are produced into sharp spines, which serve to protect the 

 seeds. In other cases they are protected by the resin contained in 

 the scales. The development of the seed is slow. 



The pollen is shed in spring, it then remains dormant, or, rather, 

 completing its development, for more than a year, and the ovule is 

 not fertilised till the following July, more than twenty months 

 after its commencement. 



Juniperus. — We have two species. In J. communis the flowers 

 are usually dioecious. 



The fruit of the Juniper is known as a galbulus. It is com- 

 posed of decussating whorls of three scales, which are evidently 

 homologous with leaves, and serially continuous with them. The 



Fig. 20.— Seeds of Scotch 

 Pine. Nat. size. 



SS, seed-scale ; ch, chalaza ; 

 MM, micropyles of the 

 two seeds. 



striate longitudinally. 



Hirare, Journ. Coll. Sci. Imp. Uniy, Japan, 1895 and 1898. 



