CONTENTS 
ZOOLOOY.—EXPERTMENTS ON THE DEVELOPMENT OP THE LdCBS IN AMPHIBIA . . 
By Ross G. Harrison Ji^9 
Bacteriology.— A Mechanism of Protection Against Bacterial Infection 
By Carroll G. Bull 545 
Zoology.— On the Lite-History of Giardia 
By Charles Atwood Kofoid and Elizabeth B. Christiansen 547 
Geochemistry.— The Inorganic Constituents of Alcyonarta ..... 
By P. W. Clarke and W. C. Wheeler 552 
Zoology. — An Experimental Analysis of the Origin and Relationship of Blood 
Corpuscles and the Lining Cells of Vessels . . By Charles R. Stockard 556 
