1764 the following words occur:— 1. Creator T.O. in primordio vestiit vegetabile medullare principiis constitutivis diversi corticalis, unde tot difformia individua, quot ordines naturales, prognata. 2. Classicas has plantas Omnipotens miscuit inter se, unde tot genera ordinum, quot inde plantae. 3. Genericas has miscuit natura, unde tot species congeneres, quot hodie existunt. 4. Species has miscuit casus, unde totidem quot passim occurrunt varietates. Hugo Mohl was right in rejecting Heufler’s assumption that a view resembling the modern theory of descent was contained in these paragraphs. It must be plain to any one who knows the ideas of Aristotle, Theophrastus, and Cesalpino, within the sphere of which Linnaeus is here moving, what he understands by his ‘vegetabile medullare’ and ‘corticale’; that he does not for a moment mean a plant of simplest organisation, but that both expressions indicate only the original elements of vegetation which the Creator, according to Linnaeus, united to one another at the first. He assumed that plants of the highest and of the lowest grades of organisation were originally created at the same time and alongside of one another; no new class-plants were afterwards created, but from the mingling together of the existing ones by the act of the Creator generically distinct forms were produced, and the natural mingling of these gave birth to species, while varieties were mere chance deviations from species. But it is to be noticed that in these minglings or hybridisations the woody substance of the one form which supplies the pollen is united with the pith-substance of the other form, whose pistil is thus fertilised; and so in these supposed crossings it is always the two original elements of the plant, the medullary and the cortical, which are mingled together. No further proof is wanting that this theory of Linnaeus is no precursor of our theory of descent, but is most distinctly opposed to it; it is utterly and entirely the fruit of scholasticism, while the essential feature in Darwin’s theory of descent is that scholasticism finds no place in it. CHAPTER III. DEVELOPMENT OF THE NATURAL SYSTEM UNDER THE INFLUENCE OF THE DOGMA OF THE CONSTANCY OF SPECIES. 1759-1850. From the year 1750 Linnaeus’ terminology of the organs of plants and his binary method of naming species came into general use; the opposition which his doctrines had till then encountered by degrees died away, and if all that he taught was not universally accepted, his treatment of the art of describing plants soon became the common property of all botanists.