THE annual cycle of display and bower building by Ptilinorhynchus violaceus Vieill, the satin bower bird, was discussed in Nature, 153, 685 (June 3, 1944), by A. J. Marshall. He stated that this cycle is possibly due to the effect of increasing light and that stimuli from the bower act "through the anterior pituitary" upon the gonads. The selection of coloured decorations by the male matches the epigamic colours of the female and may "serve the function of exciting himself by their resemblance to female colours". It is regrettable that Marshall omitted reference to published work on these lines when mentioning investigations carried out during 1939–41. In "A Contribution to the Biology of the Satin Bower-bird" (Australian Zoologist, 10, 95; 1941), E. Nubling considerably antedates Marshall's conclusions and in some points differs from them. Nubling found that the bower building is not associated with increasing light, for during 1922–26 he found new bowers principally erected in May and June during decreasing light, and states that in such circumstances the whole proceeding of courtship and nidification fall into the period of decreasing light. Regarding the part played by the pituitary body, Nubling wrote (loc. cit., 119), "the role of the pituitary Jn connection with such sexual manifestations as posturing during display or ceremonial is thus apparently a factor of outstanding importance", and he quoted the opinion of F. H. A. Marshall (1929) that sexual posturing in birds exercises a stimulating influence upon the anterior lobe of the pituitary.