X CONTENTS 



e. Breeding season, shedding of eggs and sperm .... 52 



f. Lunar periodicity (other species) . 56 



g. Forced shedding 57 



h. Removal of gonads 58 



Chapter 8. Species of Echinoidea near Woods Hole, and Arbacia 



lixula (pustulosa) 59 



Chapter 9. Classification, including places of occurrence and size 



of eggs when available 62 



PART II. NORMAL DEVELOPMENT 



Chapter 10. Immature egg and maturation 71 



a. Growth and differentiation of the oocyte 71 



b. Structure of the oocyte 72 



c. Reaction to sperm 73 



d. Centrifuging and gravity 74 



e. Respiration 74 



f. Permeability to water 75 



g. Polar body formation 75 



Chapter 11. Mature egg, unfertilized and fertilized .... 77 



a. Quantity of eggs in an Arbacia 77 



b. Methods of estimating volume and quantity .... 78 



c. Shape of eggs 78 



d. Size, weight and density of eggs 79 



e. Size of fertilized egg 79 



f. Variations in size 79 



g. Aberrant sized eggs and nuclei 80 



h. Effect of age, temperature, etc., on size of eggs . . .81 



i. Structure of the egg 81 



j. Membranes and layers 83 



k. Diagrams of surface layers of Arbacia and other eggs . . 85 



1. Granules 85 



Chapter 12. Sperm 87 



a. Morphology 87 



b. Swimming rate 90 



c. Motility 90 



d. Longevity 91 



e. Injury 92 



f. Agglutination 92 



g. Chemotaxis 92 



