The metanephros of the bird

Certain investigations were undertaken on the kidneys of various birds using that of the domestic fowl, as a type; and, where possible, comparing the results with those reported for other classes of animals. The vascular system was considered, to establish the statement of Spanner (1924), that the bird kidney possesses a renal portal system. Embryological, histological, and anatomical evidence, were brought forward in favour of this venous arrangement. The histology was examined with different techniques. In this connection, a comparative examination of fixation fluids was undertaken, as difficulty was experienced in the histological examination of bird kidney tissue. The histological results indicated some degree of glomerular degeneration and an Increase in proximal tubule development as compared to that of the mammal. Cytological studies were carried out on mitochondria and the Golgi apparatus. The mitochondria of the domestic fowl, and the pigeon, showed great concentration in the cells of the proximal tubule. The Golgi apparatus was investigated in the fowl; and showed a development in the cells of the proximal segment of the nephron, in excess of that in the mammal. The conclusion deduced from both these cytological studies, indicated an increase in activity of the proximal segment in the bird, over that of the mammal. A histochemical test using alkaline phosphatase, was performed, to decide whether the reported glomerular degeneration in the bird is such that glucose elimination is reduced or absent. Alkaline phosphatase is an enzyme stated to assist in the reabsorption of glucose eliminated by glomerular filtration. The results were compared with those of the classes possessing good glomerular development. It was noted that the avian kidney shows considerable evidence of alkaline phosphatase activity. Two conclusions are reached: (1) That the bird kidney shows definite evidence of tubular activity. (2) That in spite of apparent signs of degeneration, the glomerulus in the avian kidney functions comparably to that of the mammal.Science, Faculty ofZoology, Department ofGraduat