CONTENTS 
No. 1. JANUARY 
Ross G. Harrison. On relations of symmetrj^ in transplanted limbs. One 
hundred and thirty-six figures 1 
Joseph Hall Bodine. Factors influencing the water content and the rate 
of metabolism of certain orthoptera. Six figures 137 
Charles W. Metz and Jose F. Nonidez. Spermatogenesis in the fly, Asilus 
sericeus Say. Two plates (twenty-two figures) 165 
No. 2. FEBRUARY 
Harold H. Plough. Further studies on the effect of temperature on cross- 
ing over. Three figures 187 
W. E. Burge and E. L. Burge. An explanation for the variations in the 
intensity of oxidation in the life-cycle. One figure 203 
Henry Laurens and S. R. Detwiler. Studies on the retina. The struc- 
ture of the retina of Alligator mississippiensis and its photochemical 
changes. Thirteen figures 207 
Wilbur Willis Swingle. The germ cells of anurans. I. The male sexual 
cycle of Rana catesbeiana larvae. Two text figures and fifteen plates 
(one hundred and thirty-one figures) 235 
J. A. Detlef'sen and E. Roberts. Studies on crossing over. I. The effect 
of selection on crossover values. Two text figures 333 
No. 3. APRIL 
Ruth B. Howland. E.xperiments on the effect of removal of the pronephros 
of Amblystoma punctatum. Twenty-three figures 355 
W.M. A. Kepner and W. Carl Whitlock. Food i-eactions of Ameba proteus. 
Six plates (twenty-one figures) 397 
Alfred O. Gross. The feeding habits and chemical sense of Nereis virens 
Sars 427 
Leslie B. Arey and W. J. Crozier. On the natural history of Onchidium. 443 
Ul is 
