Preliminary Experiments With Aphids as Vectors of Yellow Dwarf. C.J.Drake, H.D. Tate, and H.M. Harris pages 247-250

The Accuracy of the Dilution Method of Estimating the Density of a Population of Micro-organisms. Edward S. Allen pages 251-262

New and Rare North American Collembola. Harlow B. Mills pages 263-276

Nectaries of Capsicum. J.N. Martin, A.T. Erwin and C.C. Lounsberry pages 277-286

The Relative Toxicity of Pyridine and Nicotine in the Gaseous Condition to Tribolium confusum Duval. Charles H. Richardson and Louise Haas pages 287-298

Quantitative, Biometric and Host-Parasite Studies on Eimeria miyairii and Eimeria separata in Rats. E.R. Becker, Phoebe Hall, and Anna Hager pages 299-316

A Discussion of Synonymy in the Nomenclature of Certain Insect

Flagellates, With the Description of a New Flagellate from the Larvae of Ligyrodes relictus Say (Coleoptera-Scarabaeidae). Bernard V. Travis pages 317-325

On the Coagulation of Blood from the Cockroach, Periplaneta orientalis (Linn.), With Special Reference to Blood Smears. J. Franklin Yeager, W. Earl Shull, and Milton D. Farrar pages 325-356