In what way is the action of drugs to be discovered? : an essay / by William Sharp, M.D.

  • William Sharp
Date:
1873
Catalogue details

Licence: Public Domain Mark

Credit: In what way is the action of drugs to be discovered? : an essay / by William Sharp, M.D. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    organ, but the characters presented by every part of a plant concur in fixing its position in the scheme. And, further, anatomy and physiology are introduced. There are fifteen classes, which include 164 natural orders. These are arranged in three divisions. Acolytedons, which correspond to the cryptogams, mushrooms, lichens, lycopods, &c., eleven orders ; monocotyledons, embracing thirty orders ; and dicotyledons 123 orders. These three divisions are taken from the seed as germinating. Coesal- pinus took the seed as perfected ; Jussieu takes it as be- ginning to grow. It has then either one lobe from which one little leaf springs—monocotyledons—or two lobes from which two little leaves spring—dicotyledons. This natural method was a great improvement upon the artificial systems of Tournefort and Linnseus. De Candolle—from 1824 to 1840—adopts the same method, but carries it further, availing himself of the discovery which in the meantime had been made by Des Fontaines of the distinct structure and growth of the stem; one portion of flowering plants increasing from within, the other from without, or on the external surface. De Candolle adopts this as the basis of his arrangement, and calls those growing from within endogens, and those growing from without exogens. The first correspond to Jussieu's monocotyledons, the second to the dicotyledons. The cryptogams or acotyledons are called acrogens. This method is the one which prevails in our time. It is not founded, as the earlier systems were, upon external characters only, but very much upon the anatomy and physiology of plants. It is, so far, more likely to be per- manent, but it is not without its difficulties, nor is it free from vagueness ; for it brings many plants together Avhich have no very obvious resemblances. This will be acknow- ledged to be no unimportant matter when it is remembered that the great object of science in classification is to bring together things which are alike, and to separate things which differ. The latest improvement is that made by Professor Lindley, who has introduced into English botany the use of English names. Of these six methods of classifying the vegetable king- dom the four first belong to natural history, the similars and dissimilars being exclusively external. They are
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