IV CONTENTS 



Mary J. Hogue. The effect of media of different densities on the shape of 



amebae. Nine figures 565 



Wheeler P. Davey. The effect of X-rays on the length of life of Tribolium 



confusum. Five figures 573 



Richard Goldschmidt. A further contribution to the theory of sex. Fifty- 

 three figures 593 



