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Abstract
One of the most characteristic prop- erties of biological systems is their enormous power of discriminating between alternatives, accurately selecting one out of a huge number of possibilities and rejecting all others. This property is called speci- ficity. It is seen, for example, in the duplication of genes during cell division. Although there are millions of different kinds of genes each one is able to produce an exact replica of itself, and this process is so accurate that no mistake is made in an enormous number of cellular gener- ations. Another specific process involving the genes is the synapsis, or coming together, of the chromosomes in which the genes in one chromosome pair up with the corresponding genes in the homologous chromosome, each gene selecting its proper partner from the multitude present in the cell.1 On another level, the whole process of heredity by which the genes cause one individual to be selected from the syriads of possible individuals furnishes a very striking example of specificity. Further examples of specific biological processes might be added almost indefinitely: for example, the power of the blood to manufacture antibodies specific to a particular antigen, the power of the nervous system to respond specifi- cally to a given stimulus, the action of certain enzymes, and so forth. It is evident that an explanation of specificity would be of great importance for the understanding of living systems.
