extension is not necessarily equal throughout the mass, but may present seasonal 

 stratification. 



(2) Inversion of the orule is seen in its simplest phase in Podocarps, which are 

 isolated from Taxoids by this feature. The 'erect' ovule with distal micropyle 

 is evidently the original case ; and it is difficult to say to what extent such inversion 

 is related to the original megasporophylls, all traces of which in the Podocarps seem 

 to have disappeared. Where erect ovules are maintained (Cupressus), they may be 

 still fairly vertically orientated ; but it is interesting to note cases in which the effect of 

 inversion may be gained by a curvature of the cone-axis, as if to remove the exposed 

 micropyles from vertical illumination or other damage : thus in Taxus the ovules 

 at pollination-stage are turned to the lower side of the leafy shoots ; in Cryptomeria 



japonica the ovulate flowers are projected horizontally ; the same applies conspicuously 

 to Biota, and inversion is fairly complete in Juniperus sphaenca. Partial inversion is 

 noted in the flowering stage of Sequoia. Inversion has been independently established 

 in Araucarineae and Abietineae; though in the former the ovule may remain free as 

 in Sequoia, while it is characteristically fused up with the cone-scale in all Abietineae 

 before pollination, as also with the bract-scale in the later seed-stage in Araucaria. 

 Fusion of the ovule with the scale apparently follows the general principles of fusion 

 noted in the case of the pollen-sacs with the intercalated stalk of the stamen, and 

 subserves improved conduction and nutrition. 



(3) A second integument (' aril ') becomes typical for Podocarps and Taxoids. 

 Only in Ginkgo and Cephalotaxus does the original integument retain simple 

 differentiation with sarcotesta and sclerotesta ; the two functions of succulence and 

 sclerosis being again separated in testa and ' aril ' of Taxus and Torreya, as also 

 in some Podocarps. The aril is merely a basal collar-growth, very similar in 

 organization and conception to the first integument which protected the pollenic- 

 chamber, and apparently repeats an older growth-mechanism a second time. Its 

 vascular supply is immaterial (cf. Ginkgo). There is little to be gained by pressing 

 the homology of the cone-scale of the Abietineae with such a growth; there is 

 no evidence whatever of this formation in the Cupressineae. It is, in fact, much more 

 important to realize that all Taxoids must have originally possessed strobiloid cones 

 of megasporophylls in the manner of Pinoids and Pteridophyta, than that Pinoids 

 should have had 2 integuments in the manner of Taxoids and many Angiosperms for 

 no particular reason that can be seen. Where the cone-construction has been lost, 

 together with last vestigia of cone-scales and the possibility of any new extensions from 

 such rudimentary carpels, the 'aril' appears as a simple solution of the original 

 problem of xerophytic protection, and it is difficult to suggest a better alternative. 



(4) Sealing the Cone (Pinoids) is based on the new application of an older 

 mechanism ; that of sealing the micropyle by a secondary growth of tissue to block 

 the cavity over the nucellus (cf. Pinus). In this case a secondary growth of the 

 integument-lips makes close contact over the nucellus-apex, and the pollen-grains are 

 sealed in a closed and protected chamber. The methods adopted for similarly sealing 

 the cone-scales of the entire aggregated cone constitute the most significant part of its 

 general organization, and lead to further complications in that a mechanism must be 

 subsequently elaborated to open it up again for purposes of seed-dispersal ; again 

 paralleled in the biology of the closing in of the Angiosperm carpel, and its dehiscence 

 in the fruit-stage. 



VIII. The Sealing of the Cone : As already indicated, it may be assumed that 

 the biological necessity for protecting the sexual prothallia as vestigia of an older 

 aquatic phase from the effects of exposure to air and desiccation is the factor 

 controlling the elaboration of the more definite cone-constructions subsequent to 

 pollination ; the problem being fundamentally the same as that of the formation of 

 the Angiosperm ovary, and the sealing is equally effective though the mechanism may 

 be expressed in tissues of different morphological origin ; the essential distinction 

 being that in the Angiosperm-flower the elaboration of the ovary -chamber takes place 

 early in floral development, while in the ' naked-seeded ' Gymnosperm such mechanism 

 is subsequent to pollination. On the other hand, the story of the Conifer series 

 elegantly foreshadows the increasing precocity of this function, so that its value may 

 be estimated ; and once its significance in the life of the organism is grasped, there 



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