Explants of Chrysanthemum stem were cultured on four different media on all of which callus was produced. This callus and explant tissue was then sub‐cultured on to one of two media, making eight different treatments. One of these treatments in which explants were cultured on a medium containing 2 mg/1 1‐naphthaleneacetic acid (NAA) and 0.8 mg/1 kinetin, and then sub‐cultured onto a medium containing 1 mg/1 kinetin and 1 g/1 soya peptone produced numerous shoots. The value of this finding for the propagation of chrysanthemum is discussed.
The technical assistance of Helen Krebs, Sheila Bruce and Maria Bagnall is acknowledged. I also thank Dr. J. L. Bailey for discussions and encouragement.
The paper addresses a notion of configuring systems, constructing them from specified component parts with specified sharing. This notion is independent of any underlying specification language and has been abstractly identified with the taking of colimits in category theory. Mathematically it is known that these can be expressed by presheaves and the present paper applies this idea to configuration.We interpret the category theory informally as follows. Suppose C is a category whose objects are interpreted as specifications, and for which each morphism u : X → Y is interpreted as contravariant 'instance reduction', reducing instances of specification Y to instances of X. Then a presheaf P : Set C op represents a collection of instances that is closed under reduction. We develop an algebraic account of presheaves in which we present configurations by generators (for components) and relations (for shared reducts), and we outline a proposed configuration language based on the techniques. Oriat uses diagrams to express colimits of specifications, and we show that Oriat's category Diag(C) of finite diagrams is equivalent to the category of finitely presented presheaves over C.
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