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(1) Changes in the absorption spectra of drying oils, especially safflower, on exposure to ionizing radiation were followed. (2) Bleaching of the oil was plotted as a linear function of the logarithm of the absorption in the visible spectrumversus the dose. (3) Oxygen inhibited radiation bleaching. (4) The cost of bleaching safflower and similar oils by electrons was estimated to be about 4 cents/pound. (5) The mechanism of radiation bleaching was postulated to involve hydrogenation of the pigments by hydrogen atoms. These were obtained by dehydrogenation of the oils or by decarboxylation of fatty acids.

It is clinically evident that joints become stiff with immobilisation. Upon remobilisation, the joints of younger individuals resolve their stiffness much more readily than do older ones. In particular, the knee joints of some elderly patients, after immobilisation in flexion, fail to regain full range of motion until the posterior joint capsule is surgically released. This experience prompted a study of the course of knee joint stiffness with immobilisation and the effect of immobilisation upon the mechanical properties of a key periarticular tissue, the posterior joint capsule. Monkey knees were selected as the experimental specimens because of their similarity to man’s in anatomy, weight-bearing function, prominent posterior joint capsule development, and full extension in range of motion.