CONTENTS 



No. 1. JANUARY 



Harley N. Gould. Studies on sex in the hermaphrodite mollusc Crepidula 

 plana. I. History of the sexual cycle. Eighty-five figures 1 



Henry Laurens and J. W. Williams. Photomechanical changes in the 

 retina of normal and transplanted eyes of Amblystoma larvae. Three 

 text figures and one plate 71 



Franklin Pearce Reagan. The role of the auditory sensory epithelium 



in the formation of the stapedial plate. Ten figures 85 



Edwin Carleton MacDowell. Bristle inheritance in Drosophila. II. 



Selection. Ten figures 109 



John N. Lowe. The action of various pharmacological and other chemical 

 agents on the chromatophores of the brook trout Salvelinus fontinalis 

 Mitchill. Three text figures and one plate 147 



Henry Laurens. The reactions of the melanophores of* Amblystoma 



tigrinum larvae to light and darkness. Six figures 195 



Carey Pratt McCord and Floyd P. Allen. Evidences associating pineal 



gland function with alterations in pigmentation. Seven figures 207 



No. 2. JULY 



Harley N. Gould. Studies on sex in the hermaphrodite mollusc Crepidula 



plana. II. Influence of environment on sex 225 



Bradley M. Patten. Reactions of the whip-tail scorpion to light. Four 



figures 251 



Frank C. Mann and Della Drips. The spleen during hibernation. Four 



figures 277 



Robert T. Hance. Studies on a race of paramoecium possessing extra 



contractile vacuoles. I. An account of the morphology, physiology, 



genetics and cytology of this new race. Three plates and twelve 



charts 287 



S. 0. Mast. Conjugation and encystment in Didinium nasutum with 



especial reference to their significance 335 



William H. Cole and Carleton F. Dean. The photokinetic reactions 



of frog tadpoles 361 



Frank R. Lillie. The free-martin; a study of the action of sex hormones 



in the foetal life of cattle. Twenty-nine figures 371 



Catherine L. Chapin. A microscopic study of the reproductive system of 



foetal free-martins. Sixteen figures 453 



