THE EVIDENCE 69 



the armour of the stem of a female Cycas is com- 

 posed of the bases of three different kinds of 

 leaf the foliage-leaves, the scale-leaves, and 

 the carpels. In thus bearing its reproductive 

 leaves or sporophylls on the main stem of the 

 plant, a female Cycas is on the same level as a 

 Fern, such as the Ostrich Fern, in which the 

 sporophylls are distinct from the ordinary fronds 

 but borne on the same stem. No other living 

 Seed-plant is so simple as this, though the same 

 arrangement was common among the Seed-plants 

 of Palaeozoic age (see Chapter IV). 



The carpels of Cycas are in themselves re- 

 markable structures, and show their leaf-nature 

 more clearly than those of any other plant. In 

 Cycas revoluta, for example, the species most 

 commonly cultivated, the carpel, about nine 

 inches in length, has a broad, deeply-divided, 

 hairy blade (fig. 6); the ovules, usually six in 

 number, are borne on either side of the lower, 

 stalk-like portion. In C. circinalis the carpel is 

 narrower, and the divisions of the blade reduced 

 to teeth; in an Australian species, C. Norman- 

 byana, there are only two ovules. The species 

 of Cycas are more gymnospermous than most 

 Gymnosperms, for the ovules are fully exposed 

 all through, until they are ultimately shed as the 

 ripe seeds. The seeds of Cycas reach an extra- 

 ordinary size in some species they are about 



