1903.] Br. D. R. Scott on Seed-hearing Plants. 335 



WEEKLY EVENING MEETING, 



Friday, May 15, 1903. 



Sir Frederick Bramwell, Bart., D.C.L. LL.D. F.E.S., 

 Vice-President, in the Chair. 



D. H. Scott, Esq., M.A. Ph.D. F.E.S. 



The Origin of Seed-hearing Plants. 



When Linneus, in 17S5, brought out his famous sexual system of 

 classification, which for so long dominated systematic botany, 23 

 out of his 24 classes were occupied by Flowering plants, and one only 

 was left for the Flowerless plants or Cryptogamia. As the name 

 *' Cryptogamia" indicated, a thick veil of mystery still hung over the 

 reproductive processes of these flowerless plants. W^hen this 

 obscurity became gradually dissipated, with the aid of iniproved 

 microscopes, by the brilliant researches of Hedwig, Mirbel, Nageli, 

 Pringsheim, Cohn, Thuret, and above all, Hofmeister, and the 

 *' Cryptogamia," to quote a phrase of Professor Sachs', became the 

 true " Phanerogamia," their relative importance received better 

 recognition. In a recent classification — that of Professor Warming 

 — out of 23 classes, no less than 18 are assigned to Cryptogams. 



In spite of our vastly increased knowledge of the Cryptogamia, 

 the Flowering plants are still in the majority as regards species. 

 According to a recent census, out of about 176,000 known species of 

 plants, about 100,000 or four-sevenths are Phanerogamic. For c.-ur 

 present purpose we may speak of the Flowering plants as the seed- 

 bearing plants or Spermophyta, for, at least in recent vegetation, the two 

 characters, the grouping of the reproductive leaves in a flower and 

 the formation of a seed, go together and the latter is the more definite 

 and constant feature. The Cryptogams, such as Ferns, Mosses, 

 Seaweeds and Fungi, may in contradistinction be spoken of as the 

 spore-bearing plants or Sporophyta. In the vegetation then of the 

 present day, the seed-bearers are enormously predominant, not so 

 much in number of species as in importance, including with few 

 exceptions all plants of utility to man and almost all those of con- 

 spicuous stature, and occupying vastly the greater part of the earth's 

 land surface. 



To what do the now dominant seed-plants owe their success ? 



This is a difficult question, for all organisms are well adapted or 

 they could not exist, and nothing requires more careful discrimination 

 than the attempt to determine the exact factors which constitute the 



