IV CONTENTS 



NO. 3 OCTOBER 



T. H. Morgan. A third sex-linked lethal factor in Drosophila. Three figures 315 



Hermann J. Muller. A gene for the fourth chromosome of Drosophila 325 



Ethel Nicholson Browne. The effects of centrifuging the spermatocj^te cells of 



Notonecta, with special reference to the mitochondria. Six figures 337 



Roscoe R. Hyde. Fertility and sterility in Drosophila ampelophila. III. Efifects of 

 crossing on fertilitj^ in Drosophila. IV. Effects on fertility of crossing within and 

 without an inconstant stock of Drosophila. Twelve diagrams 343 



Eleanor L. Clark and Eliot R. Clark. On the early pulsations of the posterior 



lymph hearts in chick embrj'os : their relation to the body movements. Two charts. 373 



Raymond Pearl and Maynie R. Curtis. Studies on the physiology of reproduction 

 in the domestic fowl. VIII. On some physiological effects of ligation, section, or 

 removal of the oviduct 395 



NO. 4 NOVEMBER 



Lorande Loss Woodruff and Rhoda Erdmann. A normal periodic reorganization 

 process without cell fusion in Paramaecium. Sixty-six figures (four double coloied 

 plates) 425 



Ross G. Harrison. The reaction of embryonic cells to solid structures. Fourteen 

 figures 521 



David Day Whitney. The influence of food in controlling sex in Hydatina senta 545 



