Contents of Volume LII 



No. i. JANUARY, 1927. 



. HYMAN, LIBBIE H. The Metabolic Gradients of Vertebrate 



Embryos, III. The Chick I 



, HYMAN, LIBBIE H. The Metabolic Gradients of Vertebrate 



Embryos, IV. The Heart 39 



FRISON, THEODORE H. Experiments in Rearing Colonies of 



Bumble-Bees (Bremida) in Artificial Nests 51 



. BALL, GORDON H. Studies on Paramecium, III. The Ef- 

 fects of Vital Dyes on Paramecium caudatum 68 



No. 2. FEBRUARY, 1927. 



HOOD, C. L. The Zooclilorclla of Front onia leucas 79 



WHITING, P. W., AND WHITING, ANNA R. Gynandro- 



morphs and Other Irregular Types in Habrobracon .... 89 



HUGHES, WINIFRED. Sex-Intergradcs in Foetal Pigs 121 



.WITSCHI, EMIL. Sex-Reversal in Parabiotic Twins of the 



American Wood-Frog 137 



No. 3. MARCH, 1927. 

 . HARVEY, ETHEL B. The Effects of Lack of Oxygen on Sea 



Urchin Eggs 147 



PAGE, IRVINE H. The Composition of Woods Hole Sea 



Water 161 



PAGE, IRVINE H. The Oils of the Sea Urchin and Star Fish 



Egg l6 4 



PAGE, IRVINE H. The Electrolytic Content of the Sea 



Urchin and Star Fish Egg , 168 



KEPNER, W. A., AND JESTER, P. M. The Reaction of Hydra 



to Inanition 173 



HAASE, MARGARET R. Ciliated \Pits of Prorhynchus stag- 



nalis 185 



FRIEDMANN, HERBERT. Tcsticular Asymmetry and Sex 



Ratio in Birds 197 



WEATHERBY, J. H. The Function of the Contractile Vacuole 



in Paramecium caudatum; with Special Reference to the 



Excretion of Nitrogenous Compounds 208 



WEIMER, B. R. The Use of Nile Blue Sulfate as a Vital 



Stain on Hydra 219 



iii 



