Page:Makers of British botany.djvu/62

 42 "Exogenae" for "Dicotyledones." The system has proved itself capable of expansion to accommodate all the new genera and natural orders that have since been established: it has justified itself as a natural classification in its susceptibility to development in precision as well as in extent, and in that it has survived the many experiments made upon it during the first century of its existence.

The glory of this crowning achievement belongs to Jussieu: he was the capable man who appeared precisely at the psychological moment, and it is the men that so appear who have made, and will continue to make, all the great generalisations of science. Jussieu's achievement, like other great scientific achievements, would have been impossible without the labours and failures of his predecessors, of which some account has been given in this lecture. He himself attributed much of his success to the work of Tournefort, but it is clear that he owed at least as much to Ray: if he learned from the former the systematic importance of the gamopetalous and of the polypetalous corolla, he gleaned from the latter the value of the cotyledonary characters upon which are based his three primary subdivisions of the Vegetable Kingdom.

It has been necessary to go beyond the strict limits of the history of British Botany in order to make it clear to what extent and at what period our two distinguished fellow-countrymen contributed to the development of the natural system of classification. Enough has been said to establish the importance and the opportuneness of their contributions: if Pisa was glorified by the birth of Systematic Botany, and Paris by its adolescence, Oxford and Cambridge were honoured by its renascence. The question concerning the respective merits of Morison and Ray finds perhaps its most satisfactory answer in the words of Linnaeus (Classes Plantarum, 1747, p. 65): "Quamprimum Morisonus artis fundamentum restaurasset, eidem mox suam superstruxit methodum Rajus, quam dein toties reparavit, usque dum in ultima senectute emendatam et auctam emitteret": Morison relaid the foundation upon which Ray built. As Linnaeus points out, Ray enjoyed the advantage of a very long period of productive activity: in the thirty-four years that separated his