It is in the preface of his _Plantarum Umbelliferarum Distributio Nova_ (1672) that Morison first gave a definite statement of the principles of his method, in the following terms: "_Cumque methodus sit omnis doctrinae anima: idcirco nos tam in hac umbelliferarum dispositione, quam in universali omnium stirpium digestione, quam pollicemur, notas genericas et essentiales a seminibus eorumque similitudine petitas, per tabulas cognationis et affinitatis disponentes stirpes exhibebimus. Differentias autem specificas a partibus ignobilioribus, scilicet radice, foliis et caulibus, odore, sapore, colore desumptas adscribemus, singulis generibus singulas accersendo species: ita species diversa facie cognoscibiles, sub generibus intermediis: genera intermedia sub supremis, notis suis essentialibus et semper eodem modo sese habentibus distincta militabunt. Hic est ordo a natura ipsa stirpibus ab initio datus, a me primo jam observatus._" It is not necessary to discuss in detail the merits of Morison's work on the Umbelliferae. It will suffice to say that it was published as a specimen of the great Historia that he had in preparation--_trigesimam operis quod intendimus partem_--so that the learned world might have some idea of what they were to expect from the completed work "_quemadmodum aiunt ex ungue leonem_"; and further, that it was the first monograph of a definite group of plants, and is remarkable for the sense of relationship between the genera that inspires it. The Umbelliferae constituted _Sectio IX_ among the fifteen sections in which Morison distributed herbaceous plants. At length, in 1680, appeared the _Pars Secunda_ of the _Plantarum Historia Universalis Oxoniensis_ in which work Morison's long-expected method of classification was to be exhibited and justified. However in this respect it proved to be disappointing: partly because it was so limited in its scope, dealing with but five of his fifteen _Sectiones_ of herbaceous plants: and partly because it did not contain any complete outline of his system. It is most singular that, although he wrote so much, Morison should have died without having published any more definite information concerning his system of classification than what has been here cited. Morison's influence did not, however, cease with his death; his tradition was maintained by the publication in 1699 of the _Pars Tertia_ of the _Historia_, under the editorship of Bobart. This volume threw some welcome light upon Morison's system, inasmuch as it completed the description of the herbaceous plants, and gave a clear statement, in the form of a _Botanologiae Summarium_, of the classification resulting from the application of Morison's principles to these plants. But, even so, the revelation of the system still remained incomplete, in the absence of any account of the trees and shrubs.