of the sporophyll appears a very distant adaptation, following the case of the Cycads, 

 and curiously contrasting with that of the megasporangia on the upper surface (as in 

 Lycopodineae also). As a detail of clearly subsidiary interest may be noted the 

 change to transverse dehiscence of the pollen-sacs observed in the pendulous flowers 

 of Abies and the erect flower of Tsuga, as probably a more recent variation. 



V. The Ovulate Flower : The morphology of the ovulate flower has pre- 

 sented considerable difficulty. It is admittedly based on an elementary type of 

 strobilus, of which the microstrobilus should be the parent-form ; but it has been 

 so much modified in connexion with subsequent adaptations for the production and 

 protection of seeds, that the homologies are no longer obvious, and the existing 

 ovulate flowers may have passed through a long sequence of reduction-specialization, 

 in which useless parts have been largely eliminated. If it were not that in Cycads 

 definite bilateral leaf-forms with marginal megasporangia still persist as actual foliaceous 

 carpels (Cycas), with many stages of reduction to forms with 2 ovules borne beneath 

 a peltate cone-scale (Zamia), it would be difficult to assign any carpellary significance 

 to the members of the ovulate flowers of such types as Pinus. 



There can be little doubt, however, that the ' bract-scale ' l of the Pine-flower is 

 a vestigial carpel; though it no longer bears the megasporangia. Nor in any Conifer 

 can the ovules be said to be borne on a carpellary leaf, but at best are distinctly 

 axillary or axial in origin : this being particularly obvious in the simpler constructions 

 of the Cupressineae and Podocarps. An analogous case is seen among Lycopodineae, 

 especially in Selaginella, in which, as the megasporophyll loses its photosynthetic value, 

 the sporangium is borne in an axillary position in which it may receive food-supplies 

 from the main shoot-system rather than from the deteriorated subtending leaf; the 

 supply of food-material for reserve-storage to large spores being beyond the capacity 

 of one leaf-member. This is the more emphasized when the spores germinate 

 in situ to parasitic prothallia, and the same problem has to be met in Angiosperm 

 carpels. Hence in all types with megaspores the carpels tend to dwindle as the 

 megaspores increase in reserve-storage and future responsibilities. Such a view of 

 the vestigial nature of the functionless carpels in Conifers is borne out by their retarded 

 rate of production in developmental stages. Thus in Pinus, the limiting case in the 

 N. Temp., the bract-scales are seen as delayed and rudimentary formations on the 

 young cone-axis with naked apex (Dec.-March), as merely small scales which never 

 grow enough to close over the cone-apex in a bud-formation. 



There can be no objection to thus regarding the bract-scale as theoretically 

 a megasporophyll, but it is no longer ovuliferous, and remains as a vestigial relic ; 

 in the limit merely indicative of the original phyllotaxis-scheme, and a guide to the 

 later construction of the cone, just as, for very similar reasons, carpels may dwindle 

 and wholly disappear (except as numerical expressions) in many higher families of 

 Angiosperms, as their ovuliferous function is transferred to the new formation of 

 a ' syncarpous ' ovary (Cruciferae). 



The progressive reduction of the functionless megasporophyll is traced in many 

 types of the Comferae : where most elaborate in organization it presents a terminal 

 relic of a leaf-lamina, together with lateral lobes of suggestively ' stipular ' nature, 

 which appear to express a form of leaf-member considerably more elementary than 

 any other appendage of the Conifer axis ; as, again, possibly a vestigial relic of an 

 archaic leaf-formation, now wholly replaced in the xerophytic foliage-system (Abies, 

 Pseudoistiga). In the limit it appears as the merest scale-member (Pinus, Cupressus) ; 

 or may be wholly lost, with the result that the ovule alone remaining appears ' terminal ' 

 ( Taxus), as if a new ' axial ' formation. 



Where the original strobilus-character remains expressed, and a cone-formation 

 with many aggregated megasporangia is retained (Pinoids), the original carpellary 

 leaves may be retained as (i) protective to the ovules in bud-development (Crypto- 

 meria, Cupressus), or (2) reduced to mere scales they may assist in the mechanism of 

 pollination, and retain a more extended construction. In such case the attenuated 



1 The term ' bract-scale ' is hence objectionable, since ' bract ' implies a leaf-member subtending 

 an axillary growth of the nature of a lateral shoot. It was adopted as a concession to theories of the 

 inflorescence nature of the Pine-cone, and is retained as a fairly established provisional convention. 



9 A 2 



