Lecture XXIV. 



205 



by June in the first year it is an egg-shaped body about half a 

 centimetre long and about 0-25 cm. in diameter. It is attached 

 by a short stalk close to the apex of the supporting stem. The 

 stalk is comparatively stout and is prolonged upwards as a succulent 

 axis to the cone. On it are set some sixty or seventy small wedge- 

 like scales arranged round the axis in a series of spirals. These scales 

 are called carpels. They are at first of a succulent consistency. 

 Closer examination of the carpels shows that each is composed of 

 two parts, the large, fleshy wedge-like scale and a small spur-like 

 projection springing from its base and united to its under surface. 

 On the upper surface of the larger scale near its base and on each 

 side of its middle line is a rounded or egg-shaped body, the ovule. 

 Later on, this ovule becomes the seed and hence the fleshy scale is 

 often called the seed-scale, while the small spur-like scale is termed 

 the bract-scale. It may be men- 

 tioned that in some trees similar to 

 the pine the bract-scales are rela- 

 tively much larger, thus in the 

 larch they project beyond the 

 seed-scale and in the fir the 

 seed-scale seems to be an ex- 

 crescence upon the bract-scale. 

 In fact the whole carpel might be 

 compared to the leaf of Selaginella 

 subtending a sporangium, the 

 seed-scale corresponding to the 

 ligule disproportionately enlarged. 



At the distal end of the preceding year's growth are found seed- 

 cones which are one year old ; they are some 4 or 5 cms. long ; they 

 are green in colour and instead of standing out erect from the sup- 

 porting branch their apex is turned downwards by the curvature 

 of their stalk. The spaces between the carpels have been closed by 

 the growth of the latter and now the outer ends of the carpels fit 

 closely and cohere together, so that one sees only the outer ends 

 of the seed-scales. They appear as quadrate areas on the surface 

 of the cone and each is raised in its middle so as to resemble a 

 low blunt pyramid. When the carpels of the cones in this stage of 

 development are examined, their seed-scales are found to be much 

 enlarged and fleshy though somewhat tough structures. The 

 bract-scales on the other hand have not developed and are only 

 found with difficulty, persisting as minute tongues or spurs at the 

 inner end of the carpel. The ovules have much increased in size 

 .and are easily visible as egg-shaped whitish masses 3 or 4 mm. in 



FIG. 67. Finns silvcstris, seed-scale 

 (carpel). A, seen from above ; B, 

 from below ; and C, from the side. 

 o, ovules ; I, bract-scale. 



