Often it is possible to search and find these primordia in the fields and woods, and if they are examined under the low-power of a microscope it is possible to study how the fruit-body subsequently develops from its small beginnings and the part played by the ring and volva in the development determined. Thus the origin of the veil can be located, its development followed as well as its disintegration. When the fungus is grown in pure culture on sterile dung, or soil, or wood, or simply on artificial media prepared in the laboratory the full sequence of events can be more easily followed. This is how the professional mycologist conducts his observations. By very careful studies it has been found in recent years that the development of the fruit-body, the origin of the gills, etc. can assist in the classification of the higher fungi. Thus some species have no protective tissue around the developing gills (gymnocarpic) whilst others have one or even two, simple or complex, tissues around the developing gills or pores (hemiangiocarpic). It is these tissues which give rise to the ring, volva, cortina, etc. This most exciting part of the study of the higher fungi is illustrated in the accompanying figures (Figs. 12 & 13) along with the various types of gill-attachment mentioned in the text (Fig. 11 A-H). If the agaric has two tissues surrounding it as the cap expands and matures, first the outer tissue or skin breaks leaving pieces on the stem and/or cap and then the second skin breaks as the cap expands still further. The last skin leaves remnants on the stem and sometimes bits and pieces at the cap margin. Only now can the agaric shed its spores from the fully exposed gills. [Illustration: Fig. 11 Fig. 12 Fig. 13 Fig. 14] (v) References A. Reference Texts Some references have already been given on p. 264. Findlay, Hvass & Hvass, Lange & Hora, Nicholson & Brightman, Wakefield and Dennis and Zeitlmayr. In addition to these the following texts are suggested: Henderson, D. M., Orton, P. D. & Watling, R. (1969). _British Fungus Flora: Agarics and Boleti: Introduction_, H.M.S.O., Edinburgh. Hennig, E. (1958-60). _Handbuch für Pilzfreunde_, Jena (in German). Haas, H. (1969). _The Young Specialist looks at Fungi_, London. Pilát, A. & Usak, O. (1951). _Mushrooms_, London. Pilát, A. & Usak, O. (1961). _Mushrooms and other fungi_, London. Ramsbottom, J. (1951). _Handbook of Larger fungi_, London. Ramsbottom, J. (1953). _Mushrooms and Toadstools_, New Naturalist, London. Romagnesi, H. (1963). _Petit Atlas des Champignons_, Bordas (in French). Smith, A. H. (1963). _Mushroom Hunters’ Field-guide_, Michigan. Wakefield, E. M. (1954). _Observer’s book of Common fungi_, London. Watling, R. (1970). _British Fungus Flora: Agarics & Boleti_, Part I, H.M.S.O., Edinburgh. B. General Texts Talbot, P. M. B. (1971). _Principles of Fungal Taxonomy_, London. Webster, J. (1970). _Introduction to Fungi_, Cambridge.