As this book is intended primarily for use in the verification of materials, for ease of location we have arranged the ,alphabetical order according to their commonly accepted names. We have also provided separate indices of Synonyms and Botanical Sources. “All the drawings in this book have been made solely by ourselves from previously authenticated samples. For the drugs and spices, which usually occur commercially in the powdered form, number 60 grade powders were prepared for examination, but for the culinary herbs, which are more usually available in the whole or broken condition, fragments of a suitable size were examined. The drawings were made at a magnification of 500, using a camera lucida, from fresh mounts prepared as described in the section on Practical Methods. In preparing the drawings our aim has been to illustrate the diagnostic characters for each material and we have excluded cell *******s which are common to a morphological group but are not otherwise diagnostic, for example, aleurone grains and fixed oil globules in seeds. The descriptions, similarly, are intended to give a detailed account of the actual characters seen in the fragments rather than the
full histology of the plant organ from which the materials are derived. We have quoted dimensions of cells and other particles only when they are of value in distinguishing between closely similar materials.” Although chemical methods of analysis, especially chromatography, are now accepted as standard techniques for the identification of many vegetable materials, microscopical structure is long established as providing a most useful and reliable criterion. Microscopy is particularly applicable to the exmaination of mixtures when individual components can readily be recognised whereas no satisfactory chromatographic identification would be possible. Microscopy also has the advantages of requiring only small quantities of the material and, once the technique has been acquired, a conclusion as to whether or not a sample is genuine can be reached very rapidly.
