CONTENTS OF VOLUME XX. 



No. i. DECEMBER, 1910. 



CHILD, C. M. Further Experiments on Adventitious Reproduction 



and Polarity in Harenactis I 



PEEBLES, FLORENCE. On the Interchange of the Limbs of the Chick 



by Transplantations 14 \f 



BROWNE, ETHEL N. The Relation Between Chromosome Number 



and Species in Notonecta 19 



GOODALE, H. D. Some Results of Castration in Ducks *; . . 35 



TOWER, WM. L. The Determination of Dominance and the Modifi- 

 cation of Behavior in Alternative (Mendelian) Inheritance, by 

 Conditions Surrounding or Incident upon the Germ Cells at 

 Fertilization 67 



No. 2. JANUARY, 1911. 



MONTGOMERY, THOS. H., JR. Certain Habits, Particularly Light Re- 

 actions, of a Littoral Aranead 71 N 



ISELY, F. B. Preliminary Note on the Ecology of the Early Juvenile 



Life of the Unionida 1 77 



GARY, LEWIS R. A Study of Pedal Laceration in Actinians 81 S 



STEVENS, N.M. Further Studies on Heterochromo somes in Mosquitoes. 109 - 

 STEVENS, N. M. Preliminary Note on Heterochromosomes in the 



Guinea Pig 121 / 



No. 3. FEBRUARY, 1911. 



RICHARDS, A. The Method of Cell Division in the Development of 



the Female Sex Organs of Moniezia 123 



COKER, ROBERT E., AND SURBER. THADDEUS. A Note on the Meta- 

 morphosis of the Mussel Lampsilis lavissimus 179 S 



MclNDOO, NORMAN E. Notes on Some Arachnids from Ohio Valley 



Caves 183 v 



HARGITT, CHARLES VV. A Further Note on Keratosum complexum i87\/ 



No. 4. MARCH, 1911. 



SMITH, BERTRAM G. The Nests and Larva of Necturus 191 



DANFORTH, C. H. A 74 mm. Polyodon 201 



KING, HELEN DEAN. Studies on SexDetermination in Amphibians, IV 205 ^ 



iii 



