IV CONTENTS OF VOLUME LII. 



No. 4. APRIL, 1927. 



POPA, GREGOR T. A Lipo-gel Reaction Exerted by Follicular 

 Fluid upon Spermatozoa and its Significance (Lillie's 

 Reaction) 223 



POPA, GREGOR T. The Distribution of Substances in the 



Spermatozoon (Arbacia and Nereis) 238 



CUSTER, CLARENCE P., AND HICKS, CHARLES H. Nesting 



Habits of Some Anthidiine Bees 258 



SAYLES, LEONARD P. Origin of the Mesoderm and Behavior 



of the Nucleolus in Regeneration in Lumbriculus 278 



No. 5. MAY, 1927. 



BLUMENTHAL, REUBEN. The Effect of Cyanides on the 



Swelling of Protoplasm 313 



HOLMES, S. J. The Low Sex Ratio in Negro Births and Its 



Probable Explanation 325 



WERNER, ORILLA STOTLER. The Chromosomes of the Indian 



Runner Duck 330 



PLOUGH, HAROLD H. Defective Pluteus Larva from Iso- 

 lated Blastomeres of Arbacia and Echinarachnius 373 



PLATH, O. E. The Natural Grouping of the Bremida 

 (Bombida) with Special Reference to Biological Char- 

 acters 394 



No. 6. JUNE, 1927. 



HULPIEU, H. R., AND HOPKINS, D. L. Observations on the 



Life-History of Amceba Proteus 411 



GRAVE, BENJAMIN H. An Analysis of the Spawning Habits 



and Spawning Stimuli of Cumingia Tellinoides 418 



KATER, J. Me A. Cytology of Saccharomyces cervicice with 



Especial Reference to Nuclear Division 436 



PAYNE, NELLIE M. Measures of Insect Cold Hardiness . . . 449 



DOMM, L. V., AND JUHN, MARY. Compensatory Hyper- 

 trophy of the Testes in Brown Leghorns 458 



JUHN, MARY. Note on the Hemolytic Action of Sebright 



Serum on Leghorn Corpuscles 474 



BELLING, JOHN. Configurations of Bivalents of Hyacinthus 



with Regard to Segmental Interchange 480 



