CONTENTS OF VOLUME XLI. 



No. i. JULY, 1921 



Twenty-third Annual Report, Marine Biological Laboratory. I 

 WHITING, P. W. Studies on the Parasitic Wasp, Hadro- 



bracon brevicornis (Weswiael), 1 42 



SHULL, A. FRANKLIN. Chromosomes and the Life Cycle of 



Hydatina scnta 55 



No. 2. AUGUST, 1921 



GLASER, OTTO. Fertilization and Egg-secretions 63 



BODINE, JOSEPH HALL. Hydrogen Ion Concentration of Pro- 

 tozoan Cultures 73 



CHILD, C. M. The Axial Gradients in Hydrozoa 78 



CROZIER, W. J. Notes on Some Problems of Adaptation: 



4. The Photic Scnsitk'ity of Ogilbia 98 



5. The Phototropism of Lima 102 



6. Relation of Light to the Pigmentation of Ascidians. . 106 



7. Regarding the Pigmentation of Sti-cJwpus moebii. ... 112 



8. Concerning " Memory " in Actinians 117 



No. 3. SEPTEMBER, 1921 



FASTEN, NATHAN. Another Male Copcpod of the Genus 



Salmincola from the Gills of the Chinook Salmon 121 



LILLIE, FRANK R. Studies of Fertilization, X. The Effects 

 of Copper Salts on the Fertilization Reaction in Arbacia 

 and a Comparison of Mercury Effects 125 



KINDRED, JAMES E. Phagocytosis and Clotting in the Peri- 

 visceral Fluid of Arbacia 144 



WHITING, P. W. Studies on tlie Parasitic IV asp, Hadro- 



bracon brevicornis (Wesmacl} 153 



HARRISON, Ross G. Experiments on the Development of the 



Gills in the Amphibian Embryo 156 



WOODRUFF, L. L. The Structure, Life History, and Infra- 

 generic Relationships of Paramecium calkinsi, sp. nov.. . 171 



iii 



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