X-ray methods in histochemistry.

T H E aim of histoand cytochemical studies is to identify and eventually to quantitate substances on a microscopic level. This necessitates isolating extremely small areas for analysis, preferably in the intact biological tissue. Physical methods have proven to be of value in this respect, in particular the radiant energy micro-absorption techniques (Fitzgerald & Engstrom, 1952). The field of histochemistry is rapidly developing. In this summary, X-ray methods that have found use in histochemistry and histophysiology will be briefly discussed. Critical reviews (Glick, Engstrom, & Malmstrom, 1951; Fitzgerald & Engstrom, 1952) have recently been published.