CONTENTS OF VOLUME XL 



No. i. JANUARY, 1921 



PAGE 



LILLIE, FRANK R. Studies of Fertilization. VIII, On the 

 Measure of Specificity in Fertilization Between Two 

 Associated Species of the Sea- Urchin Genus Strongylo- 

 centrotus I 



LILLIE, FRANK R. Studies of Fertilization. IX, On the 

 Question of Superposition of Fertilization on Partheno- 

 genesis in Strongylocentrotus purpuratus 23 



HYMAN, LIBBIE H. The Metabolic Gradients of Vertebrate 



Embryos 32 



No. 2. FEBRUARY, 1921 * 



UHLENHUTH, EDWARD. Observations on the Distribution and 

 Habits of the Blind Texan Cave Salamander, Typhlomolge 

 Rathbuni 73 



NEWMAN, H. H. On the Development of the Spontaneously 



Partheno genetic Eggs of Asterina (Patiria) Miniata .... 105 



NEWMAN, H. H. On the Occurrence of Paired Madreporic 

 Pores and Pore-Canals in the Advanced Bipennaria 

 Larvce of Asterina (Patiria) Miniata together with a 

 Discussion of the Significance of Similar Structures in 

 Other Echinoderm Larvce 118 



No. 3. MARCH, 1921 



HUXLEY, JULIAN S. Differences in Viability in Different 

 Types of Regenerates from Dissociated Sponges, with 

 a Note on the Entry of Somatic Cells by Spermatozoa ... 127 



HYDE, I. H. A Micro-Electrode and Unicellular Stimulation 130 



STARR, ISAAC, JR. Effect of Variations in Oxygen Tension on 



the Toxicity of Sodium Chloride Isotonic to Sea Water ... 1 34 



LOEB, LEO. Transplantation and Individuality 143 



iii 



