47 



are similar sections in a series with Figures 21 and 22. Figure 25. — This plate 

 is given to show the predominence of sclerenchj^matous cells in the valve tissue 

 on C. rhomboidea, and which is quite a specific difference ; they are the larger 

 bodies in the picture with thickened walls. Figure 26 is a cross section of a 

 valve of a mature fruit of C. Macleayana, and depicts the row of comparatively 

 large bundles near to, and parallel with the ventral surface, and below the row of 

 oil cavities. 



XII. ORIGIN OF THE SPUR ON THE VALVES OF THE CONES. 



One of the species of the genus received its systematic designation from 

 the presence of a spur or point on the upper dorsal surface of each cone valve, 

 but during this investigation it was found that such a character was common 

 throughout, and as they could not all be one and the same species, as has 

 been suggested, it was decided to investigate the origin of this feature, for no 

 explanation of it was found in the literature at hand, although the figure of 

 Tetraclinis (C. quadrivalvis) in Sach. 2nd edition, p. 517, shows one stage of its 

 development. 



At first it was searched for at the very earliest stage of the life history 

 of the leaf, and at an apparently corresponding spot where it occurs in the mature 

 valve, near the top of the dorsal surface of the sporophyll, but without success, 

 and so it was not until the whole life history of the fruit valve was studied that 

 its origin was discovered. 



The female amentum, which may here be said to start Hfe from the last two 

 whorls of leaves, the smaller ones being the lower trio, are found at the extremities 

 of the branchlets. 



After the ovules are fertilised and as the valves develop, these two whorls 

 gradually merge into one whole at the base, where they then radiate in the same 

 plane from the axis. 



It is near the base on the upper surface of these seminiferous valves or 

 open carpels, if one may so designate them, that the ovules are borne and 

 developed ; and as soon as these are fertilised, the leaf, now a sporophyll, gradually 

 thickens in the centre just above the last or highest row of ovules as in Figure 27 

 c and d. 



This thickening proceeds quickly after fertilisation, on the upper surface 

 till quite a protuberance is formed, which eventually exceeds in height that of 

 the original apex of the sporophyll, and which latter is now thrown back as it were, — - 

 Figure 27, e io h. 



