OSBORN ZOOLOGICAL LABORATORY YALE UNIVERSITY ROSS GRANVILLE HARRISON Bronson Professor of Comparative Anatomy and Director. WESLEY ROSWELL COE Professor of Biology. LORANDE LOSS WOODRUFF Professor of Biology. ALEXANDER PETRUNKEVITCH Professor of Zoology. SIDNEY IRVING SMITH Professor of Comparative Anatomy, Emeritus. ADDISON EMERY VERRILL Professor of Zoology, Emeritus. HENRY LAURENS Assistant Professor of Biology 1916-1921. GEORGE ALFRED BAITSELL Assistant Professor of Biology. WILBUR WILLIS SWINGLE Assistant Professor of Biology. JAMES WILLIAM BUCHANAN Instructor in Biology. TABLE OF CONTENTS. Ross G. HARRISON. On relations of symmetry in transplanted limbs. LORANDE LOSS WOODRUFF. The present status of the long-continued pedi- gree culture of Paramecium aurelia at Yale University. Proceedings HENRY LAURENS AND S. R. DETWILER. Studies on the retina. The struc- LORANDE LOSS WOODRUFF. Paramecium calkinsi sp. n. Proceedings of the GEORGE A. BAITSELL. A study of the development of connective tissue in GEORGE A. BAITSELL. The use of blood plasma in the imbedding or the MARY W. PATTEN. The life history of an amicronucleate race of Didinium nasutum. Proceedings of the Society for Experimental Biology and Medicine. Vol. 18, March, 1921. ALEXANDER PETRUNKEVITCH. Standardized microphotography. Second LORANDE LOSS WOODRUFF AND HOPE SPENCER. The food reactions of the |