TRANSACTIONS OF SECTION K. 919 



pursued ; and it is to French botanists more particularly that our present classi- 

 fication is due. It may be traced from its first beginnings with Magnol in 1G89, 

 through the bolder attempts of Adanson and of Bernard de Jussieu (1759), to the 

 relatively complete method propounded by Antoine Laurent de Jussieu in his 

 'Genera Plantarum,' just 100 years later. 



The nineteenth century opened with the struggle for predominance between 

 the Jussiean and the Linnean systems. In England the former soon obtained con- 

 siderable support, notably that of Robert Brown, whose * Prodromus Florae Novae 

 Hollandise,' published in 1810, seems to have been the first English botanical work 

 in which the natural system was adopted ; but it did not come into general use until 

 it had been popularised by Lindley in the thirties. 



Meantime the Jussiean system had been extended and improved by Auguste 

 Pyrame de Candolle (1813-24). It is essentially the Candollean classification 

 which is now most generally in use, and it has been immortalised by its adoption in 

 Bentham and Hooker's ' Genera Plantarum,' one of the great botanical monu- 

 ments of the centm-y. In Germany, however, it has been widely departed from, 

 the system there in vogue being based upon Brongniart's modification (1828, 1850) 

 of de Candolle's method as elaborated successively by Alex. Braun(lS64), Eichler 

 (1876-83), and Professor Engler (1886, 1898). It must be admitted that for 

 the last fifty years the further evolution of the natural system, at any rate so far 

 as Phanerogams are concerned, has been confined to Germany. 



One of the more important advances in the classification of Phanerogams was 

 based upon Robert Brown's discovery in 1827 of the gymnospermous nature of the 

 ovule in Conifers and Cycads, which led Brongniart (1828) to distinguish these 

 plants as ' Phanerogames gymnospermes ; ' and although the systematic position of 

 these plants has since then been the subject of much discussion, the recognition 

 of the Gymnospermfe as a distinct group of archaic Phanerogams is now definitely 

 accepted. 



Moreover, the greatly increased knowledge of the Cryptogams has involved a 

 considerable reconstruction in the classification of that great sub-kingdom. One of 

 the most striking discoveries is that first definitely announced by Schwendener (1869) 

 concerning Lichens, to the effect that the body of a Lichen consists of two distinct 

 organisms, an Alga and a Fungus, living in symbiosis; a discovery which was so 

 nearly made by other contemporary botanists, such as de Bary, Berkeley, and 

 Sachs, and which can be traced back to Haller and Gleditsch in the eighteenth 

 century. 



But the discoveries which most affected the classification of the Cryptogams are 

 those relating to their reproduction. Whilst it bad been recognised, almost from 

 time immemorial, that Phanerogams reproduce sexually, sexuality was denied to 

 Cryptogams until the observations on Liverworts and Mosses by Schmidel and by 

 Hedwig (of whom it was said that he was born to banish Cryptogamy) in the 

 eighteenth century ; and even as late as 1828 we find Brongniart classifying the Fungi . 

 and Algse together as ' Agames.' But in the middle third of the nineteenth century, 

 by the labours of such men as Thuret, Pringsheim, Cohn, Hofmeister, Naegeli, and 

 de Bary, the sexuality of all classes of Cryptogams was clearly established. It is 

 worthy of note that, although the sexuality of the Phanerogams had been accepted 

 for centuries, yet the details of sexual reproduction w^ere first investigated in Crypto- 

 gams. For it was not until 1823 that Amici discovered the pollen-tube, and it was 

 more than twenty years later (1846) before he completed his discovery by ascer- 

 taining the true significance of the pollen-tube in relation to the development of the 

 embryo ; whilst it remained for Strasburger to observe, thirty years later, the actual 

 process of fertilisation. 



The discovery of the reproductive processes in Cryptogams not only facilitated 

 a natural classification of them, but had the further very important effect of throw- 

 ing light upon their relation to Phanerogams. Perhaps the most striking botanical 

 achievement of the nineteenth century has been the demonstration by Hofmeister's 

 unrivalled researches (^1851) that Phanerogams and Cryptogams are not separated, 

 as was formerly held, by an impassable gulf, but that the higher Cryptogams and 

 the lower Phanerogams are connected by many common features. 



