CONTENTS 
vii 
The Development of Connective Tissue in the Amphibian Embryo 
By George A . Baitsell 77 
On the Hyperplasia oe Nerve Centers Resulting from Excessive Periph- 
eral Loading By S. R. Detwiler 96 
Evidence on the Nature of Nuclear Activity By D. S. Tennent 217 
The Effect of the Concentration of Nitrates on the Reducing Powers 
OF Bacteria By R. W. Glaser 272 
Studies on the Transformation of the Intestinal Flora, with Special 
Reference to the Implantation of Bacillus Acidophilus, I. Feeding 
Experiments with Albino Rats . . .By Harry A . ChepUn and Leo F. Rettger 423 
Upon an Important Method of Studying Problems of Relationship and 
OF Geographical Distribution By Maynard M. Metcalf 432 
Preliminary Report on Pterergates in Pogonomyrmex Californicus 
By Harlow Shapley 687 
Functional Regulations in Animals with Composite Spinal Cords 
By S. R. Detwiler 695 
Studies on the Transformations of the Intestinal Flora, with Special 
Reference to the Implantation of Bacillus Acidophilus, II. Feeding 
Experiments on Man By Harry A . Cheplin and Leo F. Rettger 704 
GENETICS 
Selective Fertilization in Pollen Mixtures B. D. F. Jones 66 
Model of the Linkage System of Eleven Second Chromosome Genes of 
Drosophila By W. E. Castle 73 
Transmission of Eye-Defects Induced in Rabbits by Means of Lens-Sen- 
siTizED Fowl-Serum By M. F. Guyer and E. A . Smith 134 
The Evidence for the Linear Order of the Genes 
By T. H. Morgan, A. H. Sturtevant, and C. B. Bridges. . i62 
The Arrangement of Genes in Drosophila Virilis By C. W. Metz 164 
A Contribution of Genetics to the Practical Breeding of Dairy Cattle .... 
By R. Pearl 225 
Calculating Ancestral Influence in Man By Harry H. Laughlin 235 
A Note on the Human Sex Ratio By C. C. Little 250 
The Relative Importance of Heredity and Environment in Determining 
THE Piebald Pattern of Guinea-Pigs , By Sewall Wright 320 
Observations on the Sterility of Mutant Hybrids in Drosophila Virilis 
By C. W. Metz 421 
Homologous Genes and Linear Linkage in Drosophila Virilis 
By Alexander Weinstein 625 
^The Mutant Cross veinless in Drosophila Melanogaster 
By Calvin B. Bridges 660 
Is Crossing Over a Function of Distance? By J. A. Detlefsen 663 
Interspecific Hybrids in Crepis By E. B. Babcock and J. L. Collins 670 
PHYSIOLOGY AND PATHOLOGY 
The Basal Metabolism of Boys from 1 to 13 Years of Age 
By Francis G. Benedict 7 
The Effect of Physical Agents on the Resistance of Mice to Cancer 
By J. S. Murphy 35 
The Adjustment to the Barometer of the Hemato-Respiratory Functions 
IN Man By Yandell Henderson 62 
Calcium and Magnesium Metabolism in Certa n Diseases 
By Frank P. Underhill, James A . Honeij and L, Jean Bogert 79 
