BIOLOGICAL BULLETIN 



OF THE 



flDarine Biological laboratory 



WOODS HOLE, MASS. 



VOL. L 



MAY, 1926 



No. 5 



OKADA, Y6 K. 

 BLACKER, L. J. 



BECKER, ELERY R. 



WILDER, HARRIS H. 

 HYMAN, L. H. 



CONTENTS 



On the Photogenic Organ nf the Knight- 

 jish ( Mciii'ceiitris j:if>onicus (Ilont- 

 tuyn)} 



The Dependence of Secondary Scx- 

 CHaracters upon Toticnlar Hormones 

 in Lebistes relic itlat its 



The Role of the Nucleus in the Cell 

 Functions of Amcebcc 



Palm and Sole Sttidies, IX 



The Axial Gradients in Hydrozon. < '/// 



365 



374 



382 

 393 



PETRUNKEVITCH, ALEXANDER. The Value of Instinct as a Ta.\<;n<>ii-- 



Character in Spiders . . . . 



PUBLISHED MONTHLY BY THE 



MARINE BIOLOGICAL LABORATORY 



PRINTED AND ISSUED BY 



LANCASTER PRESS, INC. 

 LANCASTER, PA. 



AGENT FOR GREAT BRITAIN 



WHELDON & WESLEY, LIMITED 



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Single Numbers, $1.00. Per Volume (6 numbers). $4.50 



Entered October 10, 1902, at Lancaster, Pa., as second-class matter under Act of Congress of July 16, 1894 



