270 TRANSACTIONS OF THE SOCIETY OF 



did not exceed 25,000 or 30,000. De Candolle modified bis plan, and 

 took up the series of families under a very much abridged form in his 

 work which he called the Prodromus. The title indicates that he at some 

 future time hoped to take up again the iSystema, but the enormous in- 

 crease in the number of species discovered, after the peace of 1815, soon 

 convinced him that this was impossible, and as the articles in the Pro- 

 tlromus were considered too brief, he lengthened the descriptions, after 

 the third volume, and continued to do so until the middle of the seventh 

 volume. There he came to the end of the great family of compound 

 flowers, the elaboration of which was his last and greatest effort. 



He was attacked by a serious illness just as he attained his sixtieth 

 year, and was obliged to accept of assistance in the work of continuing 

 the Prodromus, which he had never before done, except with articles of 

 very little consequence. jMM. Bentham, Dunal, Decaisne, Grisebach, 

 Choisy, Duby, Boissier, Moquiu, Meissuer, and Alphonse de Candolle 

 contributed their aid, and gradually furnished extended articles. De 

 Candolle expired on the 0th of September, 1811, and his son continued 

 to direct the Prodromus, preparing himself certain articles. With the 

 aid of other assistants, at the end of thirty -two years he had added ten 

 volumes to the seven that his father had published. The seventeenth 

 volume completed the principal class of the vegetable kingdom, the 

 Dicotyledons, with the exception of one family (Artocarpeis) which the 

 author could not prepare in time, notwithstanding the delay accorded 

 him. The whole forms a series of unparalleled monographs, including 

 214 families, 5,131 genera, and 58,975 species. 



The Prodromus has been, we may say, the gi'eat authority of descriptive 

 botany for half a century. Its order for families has generally been 

 adopted, its form of compilation imitated, and what it proposes or sanc- 

 tions admitted. It has been of great service in doing away with a num- 

 ber of genera and species for which there was no foundation. As the 

 work was published when most of the new plants were discovered, it con- 

 tributed greatly to making them known. It includes 657 new genera 

 and 11,790 new species ; that is to say, more than Linnaeus knew of for 

 the whole vegetable kingdom. M. de Candolle shows, by comparing 

 the volumes three by three from the commencement of the work, that 

 the proportion of new genera in relation to the old constantly dimin? 

 ishes, while the proportion of new species remains the same ; that is 

 always about 25 per cent. We may, therefore, conclude that by the 

 end of the present century we shall have discovered very nearly all the 

 genera which exist, while with species this is still far from beiiig the 

 case. 



One of the causes of the influence of the Prodromus has been its 

 entire impartiality with respect to the botanists of all countries. The 

 authors have been chosen without reference to nationality. They are 

 thirty-three in number, including MM. Candolle, and of these thirty- 

 three contributors twelve are Swiss, nine French, seven German, three 



