BIOLOGICAL BULLETIN 



OF THE 



flDarine Btolooical laboratory 



WOODS HOLE, MASS. 



VOL. LII FEBRUARY, 1927 No. 2 



CONTENTS 



HOOD, C. L. The Zoochlorella of Frontonia laicus ~<> 



WHITING, P. \\'., AND 



WHITING, ANNA R. Gynandrontorphs and Other Irregular Types in 



Habrobracon 89 



HUGHES, WINIFRED. Sex-Inter grades in Fatal Pigs 121 



WITSCHI, KMIL. Sex-Reversal in Parabiotic Twins' of the. Amer- 

 ican Wood-Frog 137 



PUBLISHED MONTHLY BY THE 



MARINE BIOLOGICAL LABORATORY 



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 Entered October 10, iooa, at Lancaster. Pa., as second-class matter under Act of Congress of July 16 , 1894 



