918 REPORT— 1900. 



We may venture to cast a forward glance upon the possible future develop- 

 ment of the knowledge of species. Various partial estimates have been made as 

 to the probable number of existing species of this or that group, but the only com- 

 prehensive estimate with which 1 am acquainted is that of Professor Saccardo 

 (1892). He begins with a somewhat startling calculation to the effect that there 

 are at least 250,000 existing species of Fungi alone, and he goes on to suggest that 

 probably the number of species belonging to the various other groups would 

 amount to 150,000 ; hence the total number of species now living is to be estimated 

 at over 400,OUO. On the basis of this estimate it appears that we have not yet 

 made the acquaintance of half the contemporary species ; so that there remains 

 plenty of occupation for systematic and descriptive botanists, especially in the de- 

 partment of Fungology. It is also rather alarming, in view of the predatory 

 instincts of so many of the Fungi, to learn that they constitute so decided a majority 

 of the whole vegetable kingdom. 



In spite of the great increase in the number of known species, it cannot be said 

 that any essentially new type of plant has been discovered during the century. So 

 far as the bounds of the vegetable kingdom have been extended at all, it has been 

 by the annexation of groups hitherto regarded as within the sphere of influence of 

 the zoologists. The most notable instance of this has occurred in the case of the 

 Bacteria, or Schizomycetes, as Naegeli termed them. These organisms, discovered 

 by Leeuwenhoek 200 yeai'S ago, had always been regarded as infusorian animals 

 until, in 1863, Cohn recognised their vegetable nature and their affinity with the 

 Fungi. These plants have acquired special importance, partly on account of the 

 controversy which arose as to their supposed spontaneous generation, but more 

 especially on account of their remarkable zymogeuic and pathogenic properties, so 

 that Bacteriology has become one of the new sciences of the century. 



Classification. 



Having gained some idea of the number of species which have been recognised 

 and described during the century, the next point for consideration is the progress 

 made in the attempt to reduce this mass of material to such order that it can be 

 intelligently apprehended; in a word, to convert a mass of facts into a science; 

 'Filum ariadneum Botanices est systema, sine quo chaos est Ees Herbaria' 

 (Linnaeus). 



The classi6cation of plants is a problem which has engaged attention fi'om the 

 very earliest times. AVithout attempting to enter into the history of the matter, 

 I may just point out that, speaking generally, all the earlier systems of classifica- 

 tion were more or less artificial, the subdivisions being based upon the distinctive 

 features of one set of members of the plant. When I say that of all these systems 

 that proposed by Linufeus (1735) was the most purely artificial, I do not imply 

 any reproach : if it was the most artificial, it was at the same time the most 

 serviceable, and its author was fully aware of its artificiality. This system is 

 generally regarded as his most remarkable achievement ; but the really great 

 service which Linnreus rendered to science was the clear distinction which he for 

 the first time drew between systems which are artificial and those which are 

 natui-al. Kecognising, as he did, his inability to frame at that period a satisfactory 

 natural system, he also realised that with the increasing number of known plants 

 some more ready means of determining them was an absolute necessity, and it was 

 for this purpose that he devised his artificial system, not as an end, but as a means. 

 The end to be kept in view was the natural classification : ' Methodus naturalis 

 est ultimus finis ISotanices ' is his clearly expressed position in the ' Philosophia 

 Botanica.' 



There is a certain irony in the fact that the enthusiastic acceptance accorded 

 to his artificial system throughout the greater part of Europe contributed to post- 

 pone the realisation of Linnseus's cherished hopes with regard to the attainment of 

 a natural classification, It was just in those countries, such as Germany and 

 England, where the Linnean system was most readily adopted that the develop- 

 ment of the natural system proceeded most slowly. It was in France, where the 

 Linnean system never secured a firm hold, that the quest of the natural system was 



