ON NATURAL ORDERS.

£11

subdivisions indicating the Orders most allied to eachother. But in the execution of this plan, difficultiesimmediately arose, especially respecting the Verti~cillatce 4£, whose leaves are invariably opposite, andthe Asperifolice 41, as regularly furnished with al-ternate leaves. Yet these two Orders could not, in anynatural arrangement, be placed asunder. So the Per .sonatce 40, chiefly opposite-leaved, were necessarilyto be classed near the Luridcz £8, and others, withalternate leaves. It is needless to point out exceptionsamongst other Orders, or tribes of Genera.

No discriminating character of his Orders, or“ Fragments,” was ever formed by Linnasus. On thecontrary, he adverts under almost every one of them,in the Prcelectiones published by Giseke, to the ano-malies or exceptions which militate against such anattempt. His judgment, as I have already hinted, isconfirmed by the result of the labours of those whohave undertaken this arduous task; though the worldis extremely indebted to them for having, in the faceof such obstacles, entered upon it. The difficulties, ap-parent contradictions, and various exceptions, whichembarrass them in the detail of their performance,are inherent in the organization of the vegetable body,in which there is throughout no positive or mathema-tical certainty. A few practical observations, illus-trative of this truth, may, not altogether unprofitably,here close the subject.

Philosophers have attributed to Nature a plastic