CONTENTS 
GEOLOGY AND PALEONTOLOGY 
PAGE 
The Composition of Brachiopod Shells By F.W. Clarke and W. C. Wheeler 262 
On the Earth Considered as a Heat Engine By George F. Becker 81 
A Correction By George F. Becker 257 
Discovery of Algonkian Bacteria By Charles D. Walcott 256 
The Origin of Coral Reefs ByW.M. Davis 146 
The Basal Silurian Formations of Eastern North America . . By Charles Schuchert 359 
The Inorganic Constituents of Alcyonaria . .. .By F.W. Clarke and W. C. Wheeler 552 
The Mission Range, Montana By W. M. Davis 626 
MINERALOGY AND PETROLOGY 
PAGE 
On the Monticellite-Like Mineral in Meteorites, and on Oldhamite as a 
Meteoric Constituent By George P. Merrill 302 
Researches on the Chemical and Mineralogical Composition of Meteorites 
By George P. M err ill 429 
The Correlation of Potassium and Magnesium, Sodium and Iron, in Igneous 
Rocks By Henry S. Washington 574 
BOTANY 
PAGE 
Phoradendron By William Trelease 30 
The Morphology and Relationships of Podomitrium Malaccense, (Steph.) 
By Douglas II. Campbell 36 
A Phylogenetic Study of Cycads By Charles J. Chamberlain 86 
A Method of Prophesying the Life Duration of Seeds 
By William Crocker and J. F. Groves 152 
ZOOLOGY 
PAGE 
Dimorphism in Size of Spermatozoa and its Relation to the Chromosomes 
By Charles Zeleny and E. C. Faust 91 
The Fertilizing Power of Sperm Dilutions of Arbacia By Frank R. Lillie 156 
Ecology of the Murray Island Coral Reef By Alfred Goldsborough Mayer 211 
Changes in Shade, Color and Pattern in Fishes and their Bearing on Certain 
Problems of Behavior and Adaptation By S.O. Mast 214 
Some Experiments on Spermatogenesis in Vitro By Richard Goldschmidt 220 
The Alcyonaria as a Factor in Reef Limestone Formation ByL.R. Gary 285 
Mitosis in Trichomonas By Charles Atwood Kofoid and Olive Swezy 315 
Localization of the Hereditary Material in the Germ Cells. .By T. H. Morgan 420 
Why Polar Bodies Do Not Develop By Edwin G. Conklin 491 
The Life Cycle of Trypanosoma Brucei in the Rat and in Rat Plasma 
By Rh. Erdmann 504 
Experiments on the Development of the Limbs in Amphibia . . By Ross G. Harrison 539 
On the Life History of Giardia 
By Charles Atwood Kofoid and Elizabeth B. Christiansen 547 
Experimental Analysis of the Origin and Relationship of Blood Corpuscles and 
THE Lining Cells of Vessels By Charles R. Stockard 556 
The Influence of the Marginal Organs on Functional Activity in Cassiopea 
xamachana By Leivis R. Gary 611 
The Relative Stimulating Efficiency of Spectral Colors for the Lower 
Organisms By S. O. Mast 622 
