The President's Address. By Dulcinficld R. Scott. 149 



reduced. The seeds, even if unfertilised, may attain the size of 

 large plums, and from their bright colours are conspicuous objects. 



In bearing the seeds on leaves comparatively little modified, 

 Oi/cas approaches nearest of any living plants to the Palaeozoic 

 Pteridosperms, where, as we have seen, all the evidence points to 

 the seeds having been developed on the rachis of the frond. 



In the other genera of Cycadacese the carpels are more 

 specialised, bearing two marginal ovules each, and are grouped in 

 definite terminal cones. 



Throughout the family the male sporophylls or stamens are 

 borne in cones ; each stamen produces numerous pollen-sacs on its 

 lower surface, which are grouped in sori like the sporangia of Ferns. 

 The seeds of Cycads agree closely with those of the fossil Pterido- 

 sperms in many respects. Here we need only mention the posses- 

 sion of a pollen-chamber, an excavation in the tip of the nucellus 

 or central body of the ovule, in which the pollen-grains are received, 

 and in which their germination takes place. The presence of 

 this organ was first discovered and excellently illustrated by our 

 countryman Griffith, as long ago as 1854.* As we saw in the 

 case of Lagcnostoma, the pollen-chamber is a conspicuous feature 

 in the structure of Pteridospermous and other Palaeozoic seeds. 



The fact that in the Cycadacere, as also in the Maidenhair Tree, 

 fertilisation is effected by means of actively moving spermatozoids, 

 as in Ferns and other Cryptogams, was discovered by the two 

 Japanese botanists Ikeno and Hirase in 1896, and independently 

 confirmed by the researches of Webber, in America. The proof 

 thus afforded that in their method of fertilisation these lower 

 Gymnosperms are exactly intermediate between the Cryptogams and 

 the higher seed-plants, is one of the most striking contributions to 

 our knowledge of the evolution of plants, and harmonises well with 

 the conclusions we have drawn from a study of the Palaeozoic 

 forms. 



Of all living seed-plants the Cycads stand nearest the Ferns 

 among Cryptogams. The Pteridosperms of the Palaeozoic era, 

 however, approached the latter much more closely still, and appear 

 to afford convincing evidence of the descent of the Gymnospermous 

 seed-plants from ancestors of the same stock with the Ferns. 



* Icones Plant. Asiat., part 4, pis. 377 and 378 ; Notulae ad. Plant. Asiut., 1854, 

 pp. 6-8. 



