460 



SCIENCE. 



[N. S. Vol XII. No. 300. 



devoting an occasion such as the present to 

 a review of the century which has closed, as 

 some will have it, or, in the opinion of 

 others, is about to close. I therefore pro- 

 pose to address you upon the progress of 

 Botany during the nineteenth century. 



I am fully conscious of the magnitude of 

 the task which I am undertaking, more 

 especially in its relation to the limits of 

 time and space at my disposal. So event- 

 ful has the period been that to give in any 

 detail an account of what has been accom- 

 plished during the last hundred years 

 would mean to write the larger half of the 

 entire history of Botany. This being so, 

 it might appear almost hopeless to attempt 

 to deal with so large a subject in a presi- 

 dential address. But I trust that the very 

 restrictions under which I labor may prove 

 to be rather advantageous than otherwise, 

 inasmuch as they compel me to confine at- 

 tention to what is of primary importance, 

 and thus to give special prominence to the 

 main lines along which the development of 

 the science has proceeded. 



STATISTICS. 



We may well begin with what is, after 

 all, the most fundamental matter, viz, the 

 relative numbers of known species of plants 

 at the beginning and at the end of the cen- 

 tury. It might appear that the statistics 

 of plants was a subject susceptible of very 

 simple treatment, but unfortunately this is 

 not the case. It must be remembered that 

 a ' species ' is not an invariable standard 

 unit, like a pound or a pint, but that it is 

 an idea dependent upon the subjectivity 

 of individual botanists. For instance, one 

 botanist may regard a certain number of 

 similar plants as all belonging to a single 

 species, whilst another may find the differ- 

 ences among them such as to warrant the 

 distinction of as many species as there are 

 plants. It is this inevitable variation in 

 the estimation of specific characters which 



renders it difficult to deal satisfactorily 

 with plants from the statistical point of 

 view. However, the following figures may 

 be regarded as giving a fair idea of the in- 

 crease in the number of ' good ' species of 

 living plants. 



It is generally stated that about 10,000 

 species of plants were known to Linnseus 

 in the latter half of the eighteenth century, 

 of which about one-tenth were Crypto- 

 gams ; but so rapid was the progress in the 

 study of new plants at that time that the 

 first enumeration of plants published in 

 the nineteenth century, the ' Synopsis ' of 

 Persoon (1807) , included as many as 20,000 

 species of Phanerogams alone. Turning 

 now to the end of the century, we arrive 

 at the following census, for which I am 

 indebted mainly to Professor Saccardo 

 (1892) and to Professor de Toni who has 

 kindly given me special information as to 

 the Algse : 



Species of Phanerogams indicated in Bentham and 



Hooker's ' Genera Plantaruin ' {Durand, 



'Index,' 1888). 



Dicotyledons 78,200 



Monocotyledons 19,600 



Gymnosperms 2,420 



100,220 

 Estimated subsequent additions (Sac- 

 cardo) 5,011 



Total Phanerogams .105,231 



Species of Pieridopliyta (indicated in Hooter and 



Baker's ' Synopsis ' ; Baker's ' New Ferns ' 



and ' Fern Allies ' ) . 



Filicinas (including laoetes), about.. 3,000 



Lycopodinse, about 432 



Equisetinse, about 20 



Total Pteridophyta 3,452 



Species of Bryophyta {Saccardo's Estimate). 



Musci 4,609 



Hepatiwe 3,041 



Total Bryophyta 7,650 



Species of Thallophyta. 



Fungi (including Bacteria) (Sac- 

 cardo) 39,663 



Lichens (Saccardo) 5,600 



Algse (incl. 6000 Diatoms) (deToni). 14,000 



Total Thallophyta 59,263 



