PDF - CES (IISc)

xxviii INTRODUCTION
species is a morphological rather than a physiological unit, and it is not the
structures but the cell-products that are affected by reagents. Those most
commonly in use are saturated solutions of potash and of bleaching-powder
(calcium hypochlorite). The former is cited in text-books as KOH or simply
as K, the latter as CaCl or C. The C solution deteriorates quickly and
must, therefore, be frequently renewed to produce the required reaction,
i.e. some change of colour. These two reagents are used singly or, if con-
jointly, K followed by C. The significance of the colour changes has been
considered in the discussion on lichen-acids.
Iodine is generally cited in connection with its staining effect on the
hymenium of the fruit; the blue colour produced is, however, more general
than was at one time supposed and is not peculiar to lichens ; the asci of
many fungi react similarly though to a less extent. The medullary hyphae
in certain species also stain blue with iodine.